Final Report-Building Code July 15 09.pdf

Recommendation for Update of

Nepal National Building Code

Final Report

July, 2009

Submitted by:

MULTI Disciplinary Consultants (P) Ltd. P.O. Box 5720, Kathmandu, Nepal

Tel: (977)-1-5525076/5529304, Fax: (977)-1- 5523103

E-mail: [email protected], Web Site: www.MultiNepal.com/mdc

in associaton with

K.D. Associates (P) Ltd. P.O. Box 686

Tel: 425263, Fax: 4215341

E-mail: [email protected],

Web: www.hurarah.com.np

and

Khwopa Engineering College Libali, Bhaktapur-2

P.O. Box 84, Bhaktapur, Nepal

Tel: 6614794, 6614798

E-mail: [email protected]

The Government of Nepal

Ministry of Physical Planning and Works

Earthquake Risk Reduction and Recovery Preparedness Programme for Nepal

(UNDP/ERRRP-Project: NEP/07/010)

mailto:[email protected]

http://www.multinepal.com/mdc

mailto:[email protected]

Recommendation for Update of Nepal National

Building Code: Final Report Contents

Executive Summary ........................................................................................................................ 6

1 Introduction ......................................................................................................................... 10

1.1 General ................................................................................................................................... 10

1.2 The Project ............................................................................................................................. 10

1.3 The Assignment ...................................................................................................................... 10

1.4 Objectives of the Assignment ................................................................................................ 10

1.5 Scope of Works ...................................................................................................................... 11

1.6 Methodology .......................................................................................................................... 11

1.7 The Project Team, Inputs and responsibilities ....................................................................... 11

1.8 Interaction with the Target Groups ........................................................................................ 12

1.9 Major Findings ....................................................................................................................... 12

2 Current Practices ................................................................................................................ 14

2.1 National Policy ....................................................................................................................... 14

2.2 Implementation of NNBC by Municipalities ......................................................................... 14

2.3 Building Permit Process in LSMC ......................................................................................... 14

2.4 Building Permit Process in KMC ........................................................................................... 15

2.5 Data and information on building code implementation ........................................................ 15

2.5.1 Government Buildings by DUDBC ........................................................................ 15

2.5.2 Practice in Municipalities ........................................................................................ 16

2.6 Institutional Arrangements for Implementation of NNBC .................................................... 16

2.7 Jurisdiction of Application of NNBC ..................................................................................... 17

2.8 Subscribed methods (PWD) of Seismic design consideration ............................................... 17

3 Consideration of Problems and Issues of NNBC Application and Construction ......... 18

3.1 The Codes ............................................................................................................................... 18

3.2 Hierarchy of Act, Bylaws, Codes and Standards, and References ......................................... 19

3.3 Building bylaws ...................................................................................................................... 19

3.4 Code Structure and Nepal Standards ...................................................................................... 19

3.5 Need for Unified Code ........................................................................................................... 19

3.6 Criticism of NNBC ................................................................................................................. 19

3.7 Family of Codes ..................................................................................................................... 20

3.8 Frequency of Update .............................................................................................................. 20

3.9 Commentary on Codes and Standards ................................................................................... 20

3.10 Conservation of Historic Building, Aesthetics, Planning Codes............................................ 20

3.11 Relationship between Aesthetics and Structural Safety ......................................................... 21

3.12 Change in Occupancy ............................................................................................................. 21

3.13 High Rise Buildings ............................................................................................................... 21

3.14 Detailing of Joints .................................................................................................................. 21

3.15 Quality Monitoring and Advertisement Market ..................................................................... 21

3.16 Supervision of Construction Works ....................................................................................... 21

3.17 Building Material Handling, storage and use ......................................................................... 22

3.18 Specification of other Materials not mentioned in NNBC ..................................................... 22

3.19 Mechanism for addressing Technical issues and data bank ................................................... 22

3.20 Participation of masons, stakeholders, owners ....................................................................... 22

3.21 Info dissemination and Interactions ....................................................................................... 22

3.22 Construction Safety ................................................................................................................ 22

3.23 Ownership of Design and Intellectual Property rights ........................................................... 22

3.24 Education ................................................................................................................................ 23

3.25 Capacity of personnel, qualification ....................................................................................... 23

3.26 Licensing of Skill Labor ......................................................................................................... 23

4 Implementation of Codes and Standards ......................................................................... 23

4.1 Water Supply and Sanitation .................................................................................................. 23

4.2 Electrical Code ....................................................................................................................... 23

4.3 Fire Safety Code ..................................................................................................................... 23

4.4 Use of NNBC 205: MRT ....................................................................................................... 24

5 Review of NNBC ................................................................................................................. 24

5.1 Review of NBC 000: 1994 State-Of-The Art Design And NBC 105: 1994 Seismic Design

Of Buildings In Nepal ............................................................................................................ 24

5.1.1 General .................................................................................................................... 24

5.1.2 NNBC 000: 1994 Requirements For State-Of-The Art Design .............................. 25

5.1.3 NNBC 105: 1994 Seismic Design Of Buildings In Nepal ...................................... 27

5.2 Review of NNBC 101, 102, 103, 104, 106, 108, 109 (Loads, Occupancy, Site

Consideration, Unreinforced Masonry) ............................................................................. 35

5.2.1 NNBC 101:1994: Materials Specifications ............................................................. 35

5.2.2 NNBC 102:1994: Unit Weight of Materials ........................................................... 36

5.2.3 NNBC 103:1994: Occupancy Load (Imposed Load) .............................................. 36

5.2.4 NNBC 104:1994: Wind Load ................................................................................. 37

5.2.5 NNBC 106:1994: Snow Load ................................................................................. 38

5.2.6 NNBC 108: 1994 Site Consideration ...................................................................... 40

5.2.7 NNBC 109: Masonry (Unreinforced) ..................................................................... 41

5.3 Review of NNBC: 107 (Fire Code) ...................................................................................... 42

5.3.1 General .................................................................................................................... 42

5.3.2 Main Objectives and Purpose of Building Codes ................................................... 42

5.3.3 Compliance to the Fire Code of Nepal .................................................................... 43

5.3.4 Major Drawback ...................................................................................................... 43

5.3.5 Requirement of Fire Safety in Building Codes ....................................................... 43

5.4 Review of NNBC: 110, 111, 112, 113, 114 (Masonry, PCC, Materials, Construction

Safety) .................................................................................................................................... 44

5.4.1 NNBC 110: Plain and Reinforced Concrete ..................................................................... 44

5.4.2 NNBC-111: 1994: Steel ....................................................................................................... 44

5.4.3 NNBC-112: Timber 1994 .................................................................................................... 45

5.4.4 NNBC-113: Aluminum 1994 .............................................................................................. 45

5.4.5 NNBC 114:1994 CONSTRUCTION SAFETY ................................................................ 46

5.5 Review of NNBC: 201, 202, 203, 204, 205 (MRT, Low Strength and Earthen Buildings)

................................................................................................................................................ 46

5.5.1 General .................................................................................................................... 46

5.5.2 NNBC 201: Mandatory Rules Of Thumb - Reinforced Concrete Buildings with

Masonry Infill .......................................................................................................... 47

5.5.3 NNBC 202: MRT-LOAD BEARING MASONRY ................................................ 47

5.5.4 NNBC 203: 1994 - Guidelines For Earthquake Resistant Building Construction:

Low Strength Masonry ............................................................................................ 48


Earthen Building (EB) ............................................................................................. 49

5.5.6 NNBC 205: 1994 - MRT Reinforced Concrete Buildings without Masonry Infill 49

5.6 Review of NNBC 206: 2003 - Architectural Design Requirements ................................. 50

5.6.1 General .................................................................................................................... 50

5.6.2 High Rise Buildings ................................................................................................ 50

5.6.3 Other aspects ........................................................................................................... 50

5.7 Review of NNBC 207: 2003- Electrical Code ..................................................................... 51

5.8 Review of NNBC 208: 1994 - Plumbing and Sanitation ................................................... 51

5.8.1 Water Supply ........................................................................................................... 51

5.8.2 Waste Water Disposal ............................................................................................. 51

5.8.3 Rain Water Disposal ................................................................................................ 52

6 Conclusion ............................................................................................................................. 53

7 Recommendation .................................................................................................................. 54

Appendix-1: List of NNBC ...................................................................................................... 57

Appendix-2: Check list of activities for the study ................................................................. 57

Appendix-3: Interaction with Target Groups and National Workshop ............................. 57

Appendix-4: Review of NNBC: 000, 105 (State of Art, Seismic Design) ............................ 57

Appendix-5: Review of NNBC 101, 102, 103, 104, 106, 108, 109 (Loads, Occupancy, Site

Consideration) ..................................................................................................................... 57

Appendix-6: Review of NNBC: 110, 111, 112, 113, 114, (Materials) .................................. 57

Appendix-7: Review of NNBC: 107 (Fire Code) ................................................................... 57

Appendix-8: Review of NNBC: 201, 202, 203, 204 and 205 (MRT) .................................... 57

Appendix-9: Review of NNBC: 206 (Architectural Code) ................................................... 57

Appendix-10: Review of NNBC: 207 (Electrical Code) ..................................................... 57

Appendix-11: Review of NNBC: 208 (Water Supply and Sanitation) .............................. 57

Reference Materials ...................................................................................................................... 57

Abbreviations:

ADRC Asian Disaster Reduction Center

ADPC Asian Disaster Preparedness Center

ASTM American Society for Testing of Materials

AASHTO American Association of State Highway and Transport Officials

AREMA American Railway Engineers and Maintenance-of-way Association

ACI 318 American Concrete Institute

AISC American Institute of Steel Construction

AFPA American Forest and Paper Associations

BPU Building Permit Unit

BCPR Bureau of Crisis Prevention and Recovery

BSI British Standards Institution

DDC District Development Committee

DIN German Standards

DUDBC Department of Urban Development and Building Construction

ERRRPP Earthquake Risk Reduction and Recovery Preparedness Programme

ESS Earthquake Safety Section

FSCN Fire Safety Code of Nepal (NNBC 107)

HFA Hyugo Framework for Action (2005-2015)

GON Government of Nepal

IRC Indian Road Congress

ISI Indian Standards Institution

ICC International Code Council

IFC International Fire Code,

IBC International Building Code

IRP International Recovery Platform

JSI Japanese Standard Institute

KMC Kathmandu Metropolitan Corporation

KVTDC Kathmandu Valley Town Development Committee

LSMC Lalitpur Sub-Metropolitan City

LSGA Local Self-Governance Act 1999

LSGA Local Self Governance Act of Nepal, 1996 and Regulations 1997

LSGR Local Self-Governance Regulations 1999

LSM Low Strength Masonry

NBCI National Building Code of India,

NFPA National Fire Protection Act

NNBC Nepal National Building Code

OBC Ontario Building Code

PWD Public Works Directives

SAARC South Asian Association for Regional Cooperation

UNDP United Nations Development Program

VDC Village Development Committee

UKBC UK Building Regulations 2000

UDB Urban Development Byelaws of 2007, KVTDC, GON

Executive Summary

Introduction The assignment for preparation of the recommendation report for Updating the National Building

Code of Nepal is entrusted to MULTI Disciplinary Consultants (P) Ltd in association with KD

Associates (P) Ltd. and Khwopa Engineering College through a contract agreement signed

between the consultant and Earthquake Risk Reduction Recovery Preparedness Programme for

Nepal - UNDP/ERRRP-Project: NEP/07/010 (The Project) on December 15, 2008.

The Project The ―Earthquake Risk Reduction and Recovery Preparedness Programme for South Asian

Region‖ is supported by the Government of Japan under a grant assistance for disaster prevention

and disaster reconstruction contributed through the United Nations Development Programme

(UNDP). The Project is designed to seek regional cooperation through sharing of knowledge and

experience in Disaster Management and to utilize the knowledge of recent Earthquake

Engineering.

Objectives of the Assignment

The objectives of the Assignment are to: a) review and recommend technical additions, alterations

and modifications, to be made in the current code, b) study, analysis and justify for update of the

Code, c) review general practice of NNBC [implementation] in some municipalities (Kathmandu

and Lalitpur), and d) study the effectiveness of implementation of NNBC in construction.

Scope of Works

The scope of works related to above mentioned Objectives is to: a) interact with major

stakeholders and experts, b) study linkages with current building bylaws, c) analyze the problems

faced by Kathmandu and Lalitpur in implementation of NNBC, d) study technical issues raised by

designers and professionals, e) compare NNBC with other codes, e) review the specific

Earthquake Safety specifications, f) specify the technical details in the code to be updated for

overall revision of NNBC, g) specify the names of codes to be urgently updated, and h) prepare

final recommendation report for updating of NNBC.

Interaction with the stakeholders

The interaction with the stakeholders such as UNDP/ERRRP, NEA, SEEN, SCAEF, SONA,

SEANEP, Licensed Designers of LSMC and KMC was carried out in four different meetings. A

national level workshop was organized on June 29, 2009 by ERRRP to discuss on the Draft Final

Report. The outcome of the interaction and comments obtained during the workshop covered

various aspects of NNBC and presented in Appendix-3 and summarized in Section 2.8. The

comments and suggestions relevant to the current assignment had been incorporated in the report

whereas certain queries which are not related to the Terms of Reference were included in

Appendix-3 for consideration during the actual revision of the Codes.

Apart from the details on the provisions of NNBC, the important aspects raised were:

Confusion of Hierarchy and Priority of Acts, Bylaws, Codes, Standards, Directives,

specifications, manuals, and References and Priority of the documents;

Need for mechanism to implement the codes as part of the Building Bylaws

Need for application of the code all over the country including VDC and small settlements

Need of Unified Code and other codes as Architectural Code, Residential Code, Historical

Building Code, High Rise Building Code, Fire Code, Plumbing Code, Construction Safety

Code, Retrofitting and Building Strengthening Code, Disabled Accessibility Code, Mechanical

Code, Fuel and Gas Code, Environmental Code and Commentary on Codes.

Anomalies of NNBC

Frequency of Updates of Codes and Responsibilities

Aesthetics, Change in Occupancy and Structural Safety, and annual Audit for compliance

with codes

Use of MRT

Regulation of Advertisement of construction materials

Safety during handling and storage of materials

Audit of Performance of Code implementing organisations,

Ownership and Intellectual Property Right

Education, Training, Qualification, Licensing of skilled labor.

NNBC and NS Series

There are two sets of documents available which are known as Nepal National Building Code or

Nepal Standard. Actually, both of the series address the same issues. NNBC is presented as

amendment to IS whereas NS are adaptation of IS or other standards into NS with relevant

amendments.

Normally, the codes and standards are revised and updated every 3 years. But for Nepalese case,

this may not be pragmatic and frequency of updating may be adopted differently. The

International Code Council or other institutions dedicated for code development and updating

review the codes at a regular interval, for example say 3 years. A regular process for recording of

occurrence is carried out and forwarded to the standing committees for code updating. Nepal does

not have a dedicated office for record of occurrence in relation to the need for updating of Codes

and Standards.

More detailed deliberations on specific codes are provided in Section 5 and Appendices.

MRT not to be a part of NNBC

Strong voices were noted for treating MRT as non-Code document since it is just an example of

design of various types of buildings and details following the provisions of NNBC. This document

is incomplete and do not include the requirements of other codes as Fire Code, Plumbing Code,

Environmental Code etc. The quality assurance and construction complexities are not considered.

Lalitpur Municipality from the very day of application of NNBC adopted certain changes in MRT.

This document should be developed as model examples that fulfill the requirement of all codes

and should be served as guide for proper design and shall not be a part of the Building Code.

Implementation of NNBC by Municipalities

The implementation of NNBC is made mandatory by issue of instructions by the Ministry of Local

Development but the Building Act and Building Byelaws do not include NNBC provisions and

hence remains ineffective and practically not applied in Building Permit Process. Lalitpur

Municipality initiated the application of NNBC in the Building Permit Process in voluntary

manner since 2003. Kathmandu Municipality started implementation of NNBC only since 2007.

The implementation of NNBC could not be initiated in other municipalities since the Building

Byelaws has not incorporated NNBC as part of it. It will be fundamental to include the NNBC and

other relevant Family of Codes as described in Section 3 to be included in Building Bylaws.

Mandatory Application of Bylaws through out the country

The Building Byelaws are by legislation applicable in the areas of jurisdiction of the

municipalities. Most of the areas in country side and rural areas are not covered by Building Act

and Building Bylaws making the rural areas more vulnerable for Construction Safety. This loop

hole in Building Act has prompted many builders and owners to shift to VDC areas for

construction for avoiding the need for obtaining Building Permits and avoiding application of

NNBC. This provision has defeated the purpose of NNBC in general.

Implementation of Architectural Design Requirements and Planning Guidelines

Though the Architectural Design Requirements (NNBC 206:2003) had been introduced in 2003,

the actual design had not been checked for compliance with this code and coordination with

Planning Guidelines and zoning plans been very week. The effect of coordination is clearly visible

in the haphazard development of the urban areas.

Institutional Arrangements for Implementation of NNBC

There is no single institution responsible for all earthquake related matters in Nepal. Various

institutions and agencies are responsible for various earthquake related matters, and the

coordination among them is practically not provided. For this reason, the issues related to NNBC

remain unattended and keeps waiting for a particular project to start. There is a dire need for

establishing Nepal Code Council that will address the development issues of Codes and their

implementation.

Code Structure, Nepal Standards and Family of Codes

There is a gross confusion about the hierarchy and priority of the documents in relation to Act,

Bylaws, Codes (NNBC), Standards (NS), and Directives (PWD), Specifications, Manuals

Instructions and administrative circulars. This aspect needs to be clarified and clear demarcation

and definition is required.

NNBC is a collection of individual codes. May be it would be more effective when compiled into

a unified code that takes into account the family of various other codes as Urban Planning Code,

Fire code, Plumbing Code, Electrical Code, Construction Code, Construction Safety Code etc (See

list in Section 3.6 Box 2) including provision for adoption of administrative procedures for

implementation.

Criticism on NNBC

A series of positive criticism on NNBC was spelt out during the interaction with the stakeholders.

The major issues are highlighted in Section 3.5 and details are provided in Appendix-3. Most

important of all criticism is that since the code is presented as amendment to Indian Code, it has

lost its value since there is no need to refer to an incomplete code when Indian Code is handy. The

dependency of other code has to be eliminated otherwise the international codes shall be adopted

as reference codes only. The Code requires technical and literature editing to eliminate errors and

misprints.

Review of NNBC 000 to 208 and Comparison with other Codes

The review of NNBC has been carried out and a number of issues had been identified that would

required to be considered while updating the Building Code. Comments and suggestions to every

Section of the Code are provided in Appendices. Particular attention is drawn on major issues

pointed out and few disasters that have occurred recently due to the lack of provisions in the code.

They are:

The provisions in the Codes have several ambiguous statements, Incomplete sentences,

reference to the Indian Standard Codes of Practice, absence of the Commentary, design

earthquake level is too un-conservative,

Fire Hazard in rural settlements induced by poor planning of the settlements and inadequate

consideration of Fire Safety measures

Changes in occupancy of buildings without confirming to Safety requirements,

Electrical hazards associated with lack of adherence to Electrical Code

Lack of coordination between Architectural Design Requirements and Planning and Zoning

Guidelines

Lack of Data base on Wind and Snow Loads

Lack of Data base on Building permits granted that will highlight the use of NNBC.

The updating of NNBC requires utilization of technological advancements and development of

international codes as IBC and Eurocode.

Family of Codes

Apart from the NNBC series and NS serious, the need for a numerous other codes is identified

which will be required to fulfill the purpose of achieving the safety of life and property and

enhancing comfort of living. These additional codes are listed in Section 3.5.

Environmental Code

This Code is very specific and needs to be addressed while updating the Code. The important of

this code is obvious since it affects the quality of life and its comfort. The code should introduce a

separate section for the Environmental Pollution Control covering following:

Air Pollution (Indoor and Outdoor)

Emission Control

Sound Pollution

Water Pollution

Solar pollution

Solid waste management

Visual Pollution in Urban and rural Areas

Landscaping

Public Information for Safety of Life, Property and Peaceful Living

Mandatory Rules of Thumb (MRT)

The main objective of MRT is to provide ready-to-use dimensions and details for various

structural and non-structural elements for up to three-storey reinforced concrete (RC), framed,

ordinary residential buildings commonly being built by owner-builders in Nepal that include a)

RCC framed with using brick infill walls, b) load bearing brick masonry, c) low strength rural

construction and earthen buildings.

The details in MRT designs are provided without consideration of construction requirements for

quality assurance (limitation of concrete placing from less than 1 m, allowing consolidation of

concrete, preventing honey comb in concrete and smaller dia reinforcement (10mm and 12 mm in

foundation and columns).

The designs provided in MRT should serve as good illustrations of compliance to the requirements

of all codes (family of Codes) for the designers and owners. Hence, it is considered that MRT

should not be a part of the Code.

Recommendation for Update of Nepal National

Building Code: Final Report

1 Introduction

1.1 General

The current assignment of preparation of recommendation report for Updating the National

building Code of Nepal is entrusted to MULTI Disciplinary Consultants (P) Ltd in

association with KD Associates and Khwopa Engineering College through a contract

agreement signed between the consultant and Earthquake Risk Reduction Recovery

Preparedness, Programme for Nepal - UNDP/ERRRP-Project: NEP/07/010 (The Project) on

December 15, 2008.

1.2 The Project

The Government of Japan has decided to provide a grant assistance for disaster prevention

and disaster reconstruction, with a view to contributing to the ―Earthquake Risk Reduction

and Recovery Preparedness Programme for South Asian Region‖ through the United

Nations Development Programme (UNDP).

The UNDP/BCPR, the leading agency of the International Recovery Platform (IRP, Office:

Kobe City, Hyogo Prefecture), and Japan have extended cooperation in this programme to

fulfill the requirement of the Hyugo Framework for Action (HFA 2005-2015) to reduce the

degree of damage and quickly restore earthquake damage by promoting quake-proof

capacity of buildings, taking into consideration the strengthened capability in the field of

disaster prevention of the South Asian Association for Regional Cooperation (SAARC) for

the South Asian region, including India, Nepal, Pakistan, Bangladesh and Bhutan.

The Project is designed to seek regional cooperation through sharing of knowledge and

experience in best practice on Disaster Management and utilize the knowledge of recent

Earthquake Engineering.

1.3 The Assignment

The assignment is related to preparation of recommendation report for updating of the

National Building Code of Nepal. The report will serve as base for updating of the Building

Code by the Government.

1.4 Objectives of the Assignment

The objectives of the Assignment are:

To review and recommend technical additions, alterations and modifications, to be made in

the current code

To study, analysis and justify for update of the Code

To review general practice of NNBC [implementation] in some municipalities (

Kathmandu and Lalitpur)

To study the effectiveness of implementation of NNBC in construction

1.5 Scope of Works

The scope of works related to above mentioned Objectives is:

Discussion and interaction with ERRRP/DUDBC, stakeholder municipality and other

experts

Study linkages with current building bylaws prepared by DUDBC/Town Development

Committees

Study and analyze the technical complications and problems faced by some

municipalities (Kathmandu and Lalitpur) in the implementation process of NNBC

Study Technical Issues raised by the designers and the professionals regarding the

revision of the NNBC

Study and Compare NNBC with other codes that are being practiced in Nepal such as

IS Code and others

Study other International Codes that are correlations with NNBC

Study and review the specific Earthquake Safety specifications in building codes and

guidelines already available in Nepal

Specify the technical details in the code to be reviewed and updated for overall revision

of NNBC

Specify the names of codes that have to be urgently updated

Prepare final recommendation report for updating of NNBC

Presentation of draft final report to ERRRP, UNDP,DUDBC, Municipalities and other

stakeholder organizations for comments and suggestions

Preparation of Final Report

1.6 Methodology

The methodology adopted for meeting the requirement of above scope of works is:

Collection and Study of data/information, documents on NNBC. The comprehensive list

is given in Appendix-1;

Collection and Study of data, information and documentation on building code

implementation for government buildings by DUDBC


implementation in municipalities;

Interaction with the users of the Codes as licensed designers of municipalities,

professional consultants involved in the Earthquake engineering, municipal and

government authorities, professional organizations;

Preparation of Recommendation for update of NNBC with detail information on

amendments, revisions, alterations to be made.

1.7 The Project Team, Inputs and responsibilities

The proposed team members are listed below in Table-1 along with the proposed task

assignment

Table-1: Proposed Team Members

SN Position Name Firm Input,

MM

Task Assignment

1 Project

Director

Mr. BL

Nyachhyon

Multi 1 Administration, Quality Management

Coordination

Review of Fire Code NNBC 107

SN Position Name Firm Input,

MM

Task Assignment

2 TL

Structural

Engineer

Dr. Prem

Nath

Maskey

Multi 1 Discussion and interaction

Review of Building Codes 000, 105

Compare NNBC with other codes

Study Codes correlations with NNBC

Specify the codes to be urgently updated

Prepare final recommendation report

3 Structural

Engineer

Mr. PM

Pradhan* /

Dr.

Govinda

Lamichhane

Khec 1 Discussion and interaction

Study linkages with building bylaws

Analyze the problems faced by some

municipalities

Review NNBC 110, 111, 112, 113

Specify details to be updated for overall

revision of NNBC

4 Civil

Engineer

Dr. Rekha

Shrestha


Study Issues raised by the designers

Review NNBC 101, 102, 103, 104, 108,

109, 114, 201, 202, 203, 204, 205

Review Earthquake Safety specifications

in building codes and guidelines already

available in Nepal

5 Architect

Planner

Devendra

Nath Gongal

Multi Discussion and interaction

Review NNBC 206

Architectural Code

6 Sanitary

Engineer

Shankher

Agrawal/

Kul Deep

Tuladhar

KDA 1 Discussion and interaction

Review NNBC 208

System Protection and Safety

Uninterrupted Supply

7

Electrical

Engineer

Shambhoo

Bahadur

Shrestha


Review NNBC 207,

Electrical Safety, System Protection, ,

Uninterrupted Supply * Mr. PM Pradhan could not contribute to the study since he has resigned from Khopa Engineering College.

1.8 Interaction with the Target Groups

The Appendix -3 lists the Target Groups for interaction for brain storming on updating of

NNBC. The interaction sessions were carried out as follows:

Dec 28, 2008 - Brief interaction with UNDP/ERRRP National Program Coordinator

Feb 5, 2009 – Institutional Target Groups

Feb 9, 2009 – Licensed Designers registered with Lalitpur Sub-Metropolitan City

Feb 27, 2009 – Licensed Designers registered with Kathmandu Metropolitan City

The notes on the Interaction programs are presented in Appendix-3.

1.9 Major Findings

The NNBC, described in 20 independent volumes, is mostly comprises of editing of certain

terminology of IS Codes and as such requires intensive revision and updating. Practically,

this updating cannot be done at this stage in view of availability of resources for review and

updating.

The revision and updating of NNBC are not done in a regular basis since there is no

dedicated institution for this job. The revision and updating of Building Codes are very

complex and cumbersome process that requires huge resources in terms of knowledge

accumulation, institutional memory, time, research and development and statistics. The code

updating assignment even for rich countries like USA and UK is very huge and requires

considerable investment. They have started standarisation at international level and today

most of them use International Building Code. Those codes which are not included in the

IBC are included by reference and used as a set of document agreed at international level.

Each country or local governments are given rights to amend the parts which are not relevant

to the local area and needs revision.

There are no statistical records on the application of NNBC in recent construction of both

Government and Private Sectors. But it is evident that mostly used documents are MRT,

which has good stories mentioned above and does not warrantee the safety of the Building

design under it. With these facts in mind, it is required that MRT is taken away from the

family of Building Codes but a separate standard design could be developed which could be

readily used by anybody without requiring to go through the Safety review procedures in

Municipalities.

The provisions of NNBC are currently applicable within the Municipality boundaries and

there is no formal need to apply NNBC in rural areas. This weakness has to be changed and

all buildings and infrastructures in the rural areas are also required to fulfill the requirements

of NNBC.

It is recommended that as a priority MRT should be urgently discarded as part of the code

and replaced with standard design of typical buildings that complies with requirement of the

Family of Codes.

The revision and updating of NNBC should replaced by adaptation of IBC with specific

changes of certain provisions that are relevant to the country and locality.

A dedicated Institution as National Code Council shall be established urgently and entrusted

the task of development and implementation of NNBC and help to protect life and property

from various risks of Natural and manmade disasters.

The provision for implementation of NNBC shall be included in the Building bylaws which

govern the external and internal design aspects of individual buildings and infrastructure and

warrant the least effect to the neighborhood.

Though the building permit process according to Building Bylaws has granted certain

purpose to the buildings constructed in the urban areas, but there are considerable cases

when the occupancy loads were changed without proper justification and without design

revision. They pose huge risks in terms of safety.

Similarly, the case of high rise buildings needs to be looked very seriously and provide

specific guidelines for comprehensive design.

The Conclusion and recommendation are provided in Chapter 6 and 7.

2 Current Practices

2.1 National Policy

Nepal is considered one of most vulnerable country for earthquakes. The recent earthquakes

(1988 in Udayapur, Nepal) have prompted serious concerns for the earthquake safety of

infrastructure. Following the major earthquake event in 1988, the Ministry of Housing and

Physical Planning undertook a policy initiative jointly with UNDP and UNCHS to address

need for changes in current building design and construction methods. The UNDP / UNCHS

(Habitat) Project and the Ministry undertook ―Policy and Technical Support to Urban Sector

Project‖ under which national housing survey, shelter sector training needs assessment, draft

national housing policy formulation, draft national building code preparation etc. were

undertaken. The ‗Building Act‘ was adopted to facilitate the regulation of building design /

construction practice in Nepal. The ‗Engineering Council Act‘ was formulated to facilitate

self regulation of the profession by professionals themselves. The Nepal National Building

Code was prepared in 1994. At the same time The Bureau of Standards and Metrology had

developed the NNBC as Nepal Standards under various Standard Codes. But in the absence

of the Parliament the Codes and Standards remained unimplemented. The Gujarat

Earthquake of Jan 2001 prompted the Society of Consulting Architectural and Engineering

Firms (SCAEF, Nepal) initiated joint collaboration with NBSM for implementation of

NNBC and NS. The collaboration prompted to form the National Forum of Earthquake

Safety that facilitated the Declaration by Lalitpur Sub-Metropolitan City for implementation

of NNBC and initiation of Master‘s Degree Course in Earthquake Engineering by Khwopa

Engineering College.

2.2 Implementation of NNBC by Municipalities

LSMC is the First Leading Municipality in Nepal to implement NNBC in the Building

Permit Process through a declaration on the occasion of Earthquake Safety Day celebration

on January 16, 2003 (2059 BS).

The Implementation of NNBC was initially facilitated by the Technical Cell (Group of

Municipal Engineers & Engineers from DUDBC, NSET, NFES, NEA) which worked for 6

months prior to the establishment of the Earthquake Safety Section 27th November 2003

(2060 BS).

2.3 Building Permit Process in LSMC

The Building Permit Application in LSMC is processed in following steps (ref….):

Registration by the Building Permit Unit of Municipality

Checking for compliance with Building Bye-Laws

Review the design by the Earthquake Safety Section (Technical Cell in initial stage) for

compliance with NNBC

Presentation of the design by the Licensed Designer in a public forum organized by

LSMC, ESS for sharing experience, knowledge, methodology of application of NNBC,

confirmation of compliance to NNBC. This process was dropped at later stage and not

continued any more.

Building Permit is granted in two stages:

Initial Permit for construction upto Plinth Level

Final Permit after inspection of construction upto Plinth Level

Inspection of Construction Progress by Municipality Staff

Certification of Completion jointly by the Licensed Designer who supervised the

construction and Building Permit Unit who inspected the construction.

The general Building Permit process is provided in Section 2.4.2 below.

2.4 Building Permit Process in KMC

The Building Permit process in KMC differs significantly. The compliance with NNBC for

upto 3 storeys or 1000 sqft in area is reviewed by Building Permit Section and for Buildings

over 6 floors, it is checked by the National Building Code Implementation committee

(NBCIC). The detailed procedure is described below. Kathmandu Metropolitan City (KMC)

has started implementing building code-2060 from August 21, 2005, for the construction of

buildings within the city. In October 2005 a National Building Code Implementation

Committee was set up within KMC, it is comprised by six specialists who act on voluntary

basis.

The general building permit process is as follows:

Step 1: The Application for Building permit is checked for compliance with planning

guideline as Guided Land Development, particularly for adequacy of accessibility;

Step 2: For Buildings less than 3 storeys and less than 1000 Sqft, Computer checking by

Junior Engineer for compliance with requirements of NNBC and Planning Bylaws;

collection of revenue

For Buildings more than 3 storeys and more than 1000 Sqft, checking by Engineer for

compliance with requirements of NNBC and Planning Bylaws; collection of revenue

Step 3: Initial Registration and Computer Entry

Step 4: Forward to Ward Office for Field Verification and Neighborhood Consent

Step 5: Forward to Building Permit Section for Final Registration

Step 6: Checking by Engineer and Issue of Building Permit for Construction upto DPC

Level

Step 7: Checking of Construction upto DPC Level

Step 8: Issue of Building Permit for Construction of Superstructure

Step 9: Checking of Completion of Construction and Issue of Completion Certificate

Step 10: Apply for water and sewerage service connections, Electricity and

Telecommunication

Step 11: The drinking and sewerage office sends their recommendation to the Roads

Department for permission to dig the road for the water and Sewerage connection.

Step 12: The Department of Roads grants its permission to dig the road.

Step 13: Inspection by water and sewage offices and Water and sewer connection is

carried out

Step 14: Wiring Inspection before obtaining electrical power connection and telephone

connection

Step 15: Connection of Electrical Power Supply and Telephone connection

2.5 Data and information on building code implementation

2.5.1 Government Buildings by DUDBC

DUDBC carries out implementation of certain government buildings through its

construction and Maintenance divisions. It is not known how far they comply with the

requirement of NNBC and who does certify the compliance since design and construction

supervision documents and As-Built Drawings are not readily available.

2.5.2 Practice in Municipalities

Building permit system started after the endorsement of ‗Building By-Laws in 1994

(2050)‘. Simply a set of Architectural drawings consisting of plans, four side elevations,

section, location plan and site plan were required for submission and this was dealt by the

Drawing Cell. This cell was also responsible for checking the compliance with other

aspects such as coverage, FAR, GLD, zoning etc. After the introduction of NNBC, a set of

structural drawing was added to the list of requirements.

From 2003, the requirement for architectural, structural design analysis, electrical etc

drawing sheets was introduced for SOA type of buildings (Class A) while the requirement

was limited to architectural and structural drawings for Class B type buildings and Class C

type building does not require any structural design. In some cases where the area is

designated as heritage conservation area, additional design for preservation of traditional

style and vernacular architecture is emphasized and permission from the Department of

Archeology is required.

Initially, the building permit process included the technical committee for review of

designs by a panel of external experts comprising of the representatives from DUDBC,

KMC, IOE, NSET and SCAEF. This process gained very essential lessons that benefited

the crystallizing the Building Permit Process and was a learning stage for many Licensed

Designers and Building Owners. But soon, the review process felt lot of resistance since

the Licensed Designers were unable to defend their designs and the process was felt as a

burden to the Municipality. Certainly, a thorough and detailed scrutiny required excellent

preparation of the design and drawings.

There are two certificate systems one is temporary which is given after DPC check, but this

temporary certificate is postponed now. The other is the Permanent completion certificate

as obvious from the name is given after the completion check of the building construction.

Now the number of structural drawing sheets has increased from one to three and pillar

from 9‖x 9‖ to 12‖x12‖. All engineered building for residential purpose which is more

than 1000sq. ft and 3 storeys require analysis report. For commercial buildings there is a

further requirement of soil test report and other drawings such as electrical, sanitation,

plumbing.

NNBC was enforced through the endorsement of Building Act 1999, but formally it was

implemented only in 2003 because the Building Bylaws did not make any reference to the

implementation requirements of the Building Code. NNBC has categorized buildings into

four categories namely type A, B, C and D.

2.6 Institutional Arrangements for Implementation of NNBC

There is no single institution responsible for all earthquake related matters in Nepal. The

following agencies are responsible for various earthquake related matters:

Department of Mines and Geology is responsible for earthquake instrumentation

network in the country and preparation of the seismic zone map of the country.

National Bureau of Standards and Metrology is responsible for the certification of

standards and constituents of codes and guidelines on various public works including

earthquake matters.

National Building Council is envisaged as an apex body to deal with the creation and

updating of the National Building Code of Nepal.

Department of Urban Planning and Housing is responsible for the creation and

implementation of Nepal National Building Codes including earthquake matters.

Kathmandu Valley Town Development Committees are responsible for formulation of

Formulation of urban development plans, planning and building byelaws.

Local bodies (VDCs, DDCs and Municipalities) are responsible for formulation and/or

adoption of bylaws, codes, norms, regulations and enforcing / policing their

implementation in the areas of their jurisdiction.

Professional Societies as NEA, SCAEF, SONA, SEANEP, SEEN, ESI, NSET and other

Non-Government Organisations are responsible for information dissemination,

awareness campaigns, upgrading the knowledge and skill of their members to comply

with these codes in their professional practice and occasionally provide training.

Donor agencies involved in the area of earthquake safety include UNDP, UNCHS,

UNESCO and JICA.

There is no dedicated institutional arrangement for dealing with the Earthquake Safety

matters, follow up and updating of NNBC, for expert advice, and pursuance for application

of NNBC by local Governments including Municipalities and VDCs.

2.7 Jurisdiction of Application of NNBC

The Local Self-Government Act Part 2-VDC Clause 28 (f) (2) has made provision of the

criteria for construction of Buildings and Infrastructure. LSGA Part 3-Municipality Clause

96 (b) (6) has made provision for approval of Building Construction. These provisions could

be rationally utilized for application of NNBC in VDC and Municipality areas effectively.

More specific and elaborate guidelines may be required.

Building Act 2055 (amendment 1998) has given authority to all municipalities to implement

the NNBC for providing Building Permits. However, the Act do not specify a particular

organization that is authorized to follow up and monitor the compliance to NNBC by the

Municipalities.

2.8 Subscribed methods (PWD) of Seismic design consideration

PWD Part II Chapter has provided certain guideline for Earthquake Consideration in

Infrastructure Project Sector. The guidelines for earthquake considerations apply to the

following categories of structures:

All buildings having a plinth area greater than 20 m2 or height ranging from 5 m to 90

m.

All masonry and concrete walls having a height of greater than 1.5 m.

All elevated water tanks and silos with capacity up to 200 m3.

All public buildings having general public access.

All civil engineering structures such as bridges, dams, earth structures, silos, water tanks,

chimneys etc.

All towers and electric or telecom or radio pylons.

The requirements of these guidelines shall be followed at minimum. The designer is

however free to exercise more stringent procedures if considered necessary considering the

merit of the case.

3 Consideration of Problems and Issues of NNBC Application and

Construction

The problems and issues related to the application of NNBC and construction quality are

largely discussed in various interaction programs with major stakeholders and brief notes on

the discussion points are described in Appendix-3. These issues are briefly highlighted

herewith:

3.1 The Codes

A code is a set of technical specification and standards that control major details of analysis,

design, construction and equipment. The purpose of the code is to produce safe and

economic design so that people are protected from poor and inadequate design and

construction.

Two types of codes exist. One type of code is called ―Structural Code‖ and is written by

Structural Engineers and other specialists who are concerned with a particular class of

structures (e.g., buildings, bridges, nuclear plants) or who are interested in proper use of

materials (Steel, Aluminum, Reinforced Concrete, Plastics or Wood). Typically, structural

codes specify design loads, allowable stresses of various parts of structures, design

assumptions and requirements of material. Examples of Codes frequently used by structural

engineers include following:

AASHTO – Standard specification of Highway Bridges

AREMA- Manual for Railway Engineering

ACI 318 – Building Code requirement of reinforced concrete

AISC – Manual for Steel Construction

AFPA- National design Specification for Wood Construction

The second type of code, called Building Code, is established to cover construction in a

given region (a state, city or country). A building code contains provisions pertaining to

architectural, structural, mechanical, electrical, requirements. The objective of a building

code is toprotect the public by accounting for the influence of the local conditions on

construction. Those conditions of particular concern to the structural engineers cover such

topics as soil conditions, live loads, wind pressure, snow load, and earthquake forces. Today

many building codes adopt the provisions of Standard minimum design loads for Buildings

prepared by ASCE or more recent International Building Code by ICC.

As new systems evolve, as new materials or new technology becomes available, or repeated

failures of accepted design occur, the cont3ent of codes are revised and updated. In recent

years, a large volume of research on structural behavior and materials has resulted in

frequent changes in both types of codes. For example, the ACI committee issues annual

addendum and produces revised codes every 6 years.

Most codes make revision to depart from the provisions in the standard provision if the

design can prove by the test or analytical studies that such changes can produce a safe

design.

3.2 Hierarchy of Act, Bylaws, Codes and Standards, and References

There is a gross confusion about the hierarchy and priority of the documents in relation to

Act, Bylaws, Codes (NNBC), Standards (NS), and Directives (PWD), Specifications,

Manuals Instructions and administrative circulars. This aspect needs to be clarified and clear

demarcation and definition is required.

The reference to other international codes as IS, IRC, JSI, DIN, ASTM, Eurocode and others

shall be provided.

3.3 Building bylaws

The building byelaws of municipalities do not include several codes which are considered

very essential for enhancing safety and quality of Life. The safety of Neighborhood

buildings such as supermarkets, high rise buildings, hospitals, schools, institutional building,

water towers, electrical towers, communication towers etc requires special treatment and

deserves specific consideration. The existing bylaws do not deal with hazardous buildings as

abandoned and dangerous houses. The Building Permits process shall include all codes

relevant to the safety of buildings and infrastructure. Apart from this, the bylaws shall

include provisions for innovativeness in planning and design.

3.4 Code Structure and Nepal Standards

There are two sets of similar documents: One published by DUDBC under NNBC 000 to

NNBC 208, and another set published by NBSM under NS series. NNBC is basically refers

to IS with corrections made for internalizing with Nepal Requirements. So, NNBC is a

dependent code and requires intensive reference with IS. In the other hand, NS has adapted

the NNBC provisions and replaced the references of NNBC with relevant clauses adapted

from respective international codes. This duplication of NNBC and NS has created

confusion among the users of Nepal Codes. NNBC requires to be made more users friendly,

warrantee safety compared to other codes and build confidence among the professionals and

community as a whole.

3.5 Need for Unified Code

NNBC is a collection of individual codes. May be it would be more effective when compiled

into a unified code including provision for adoption of administrative procedures for

implementation.

3.6 Criticism of NNBC

Several experts and professionals have reported that NNBC contains several anomalies

which make it unreliable and confidence on it could not be developed. These factors are

related to:

The Safety factors,

Importance factors,

Response spectra,

Worse case of load combination

Low Load factors, Load reduction provision, Load distribution of non-orthogonal plan

Lateral earth pressure in basement

Load distribution for high rise and low rise

Time period < 0.1 N

Design Parameters as:

- Settlement, deformation, strength, crack opening

- Static and dynamic analysis

- Retrofitting of existing buildings by laws / codes

- Repair and maintenance of old existing buildings/ code

- Disaster mitigation – building stock inventory

3.7 Family of Codes

The International Code Council has adopted

a series of codes that comprehensively

provide safety of life and property, and

enhance the quality and comfort of the

people. This aspect has not been covered by

Building Act of Nepal and Byelaws of any

municipalities and the building codes

prepared have limited provisions. The list of

International Codes used is listed in Box-2.

These codes are part of Building By-Laws

and required to be followed as the minimum.

3.8 Frequency of Update

The Bylaws, codes and Standards required

to be updated within a certain period in

order to address the dynamic technological

development and requirement of the

consumers.

3.9 Commentary on Codes and Standards

Inclusion of Commentary on Codes and

Standards is most important since it

develops the confidence of the users, and

provides evidence of authenticity. The

commentary shall be included in the same

code and standard where it is required to be

provided.

3.10 Conservation of Historic Building, Aesthetics, Planning Codes

NNBC includes a code on Architectural

Design Requirement (NNBS 206:2003),

but the important aspects of urban areas as

conservation

of historic buildings, aesthetics and context of urban areas affecting the neighborhood safety

are missing which has a huge toll on the urban safety. The building permit process in the

vicinity of historic buildings and in the World Heritage Sites or Preservation areas are not

subject to the requirements of Department of Archeology which is the governing body for

conservation of buildings and heritage sites.

Box-2: List of International Codes in Use

1. Building Code *,

2. Residential Code,

3. Mechanical Code,

4. Plumbing Code *,

5. Fuel Gas Code,

6. Fire Code *,

7. Property Maintenance Code,

8. Private Sewage Disposal Code,

9. Electrical Code

10. Energy Conservation Code,

11. Existing Building Code,

12. Utility Codes (Lifts and Escalators, Lighting and

ventilation, Prefabrication and System buildings,

Acoustics, Noise control, Air Conditioning and

Heating, Communication and Networking) 13. Urban Wild land Interface Code,

14. Performance Code,

15. Planning and Zoning Code

16. Code and Commentary

17. Elevator Safety Construction Code

18. Historical Building and Conservation Code

19. Reference Standards Code

20. Disabled Accessibility Guidebook

21. National Green Building Standard

22. Nonstructural elements code

23. Code for Special Buildings as high rise

buildings, water towers, bridges.

24. Construction Safety

25. Environmental Codes (Indoor and Outdoor

Ambience)

26. Retrofitting and Building Strengthening Code

* Codes included in NNBC

http://www.bookmarki.com/SearchResults.asp?Search=2009+international+sewage+code

http://www.constructionbook.com/california-disabled-accessibility-guidebook-an-interpretive-manual-checklist-2009-caldag-9781580017664/icc-code-reference/

3.11 Relationship between Aesthetics and Structural Safety

In several cases, the architectural shape and size artificially dictate the type of structures to

be used which violates the structurally safety provisions. The codes shall make a distinction

of the relationship between the architectural shape and structural safety requirement.

Similarly, the building shape and configuration have effect on ductility of the building and

overall safety against Earthquake Hazard.

3.12 Change in Occupancy

There are several occasions of change of occupancy category of the buildings that threaten

the safety of life and property. Recently, several of hotel buildings have changed occupancy

to supermarkets and office buildings. The residential buildings are easily used for

accommodating lower class schools, warehouses, and offices. Such changes in occupancy

required to be monitored and shall be governed by the provisions in Building Bylaws and

codes.

3.13 High Rise Buildings

The requirement of high rise buildings in terms of overall safety is different than that of low

rise buildings. The quality of materials and reliability of technology is much stringent and

operation and maintenance of the service require higher degree for reliability. This

requirement should be covered by NNBC.

3.14 Detailing of Joints

The use of facede materials as granite, glass panels and traditional decorative bricks (Dachi

Apa) requires inclusion of detailing of joints with main structure in order to warrantee the

safety during Earthquake. The details of connection of infill walls, parapet walls, sunshades

and main frames shall be considered.

3.15 Quality Monitoring and Advertisement Market

The current practice of quality assurance of materials and their use in construction is getting

in mess. There is no uniform method of quality monitoring exits except for the voluntary

application of quality standards at the large scale project level. The materials in the market

are dominated by commercial advertisement irrespective of applicability of the products to

the specific job and requirement of quality parameters. More the advertisement materials are

misleading to the consumers since the information provided in the advertisements are not

correct or not applicable to the situation at the particular job. The business community

exploits the consumers for their lack of knowledge understanding and ignorance, and lack of

institutional approach towards monitoring the advertisement materials.

3.16 Supervision of Construction Works

This is one of the weakest parts of implementation of NNBC and NS. The qualification of

Human resources being engaged in supervision and quality of materials and equipment

required to be addressed.

3.17 Building Material Handling, storage and use

The Safety of public and labor during material handling, storage and use is not taken care of.

Use and handling of hazardous materials as fuel and electricity and other inflammable

materials shall be considered with special care. The sales of cement, steel, brick and sand at

public places are harmful to health.

3.18 Specification of other Materials not mentioned in NNBC

There are several other building materials that are commonly used in the market whereas

these materials are not included in the Codes or Standards. There should be a mechanism

where these new materials and technology could be permitted for use under the code

provisions.

3.19 Mechanism for addressing Technical issues and data bank

The mechanism for addressing technical issues on provision of codes, standards,

specification and construction technology is lacking. Similarly, data on experts on

Earthquake Safety and Building Code matters are not consolidated. A data bank on Code

and Earthquake Safety matters will be extremely helpful including the development of a

library for collection of important reports and research works.

3.20 Participation of masons, stakeholders, owners

The participation of stakeholders directly involved in the project as masons, owners and

other stakeholders in code making and updating is lacking.

3.21 Info dissemination and Interactions

Information dissemination on code related issues are not adequately made. The information

rarely reaches the concerned stakeholders as professional societies and entities. The

information on the codes and standards shall be discussed with the stakeholders at length for

making the codes more effective and popular.

3.22 Construction Safety

The Construction safety is dealt in NNBC 114: 1994. However, it is limited to certain items

and major safety issues as responsibility and accountability of safety is not considered. At

the same time several items as formwork, reinforcement, concreting, equipment operation

and many more are not included.

3.23 Ownership of Design and Intellectual Property rights

The ownership of the designer over the design and intellectual property right of the designer,

the contractor and major technology suppliers is not covered by NNBC. This will be an

important aspect to be included in the Building Code.

3.24 Education

The education in Engineering Colleges is based on course books and seldom referred to the

NNBC or other codes and remained more academic and not pragmatic. The use of code

provisions shall b encouraged for practical classes. The colleges are the best places for

building awareness on need for use of codes and standards.

3.25 Capacity of personnel, qualification

The qualification of the administrators of the codes at municipality level is another issue.

The application of codes is ignored since there is lack of adequate human resources with

knowledge of Codes. Equally, important is the qualification of the designers who are

basically responsible for compliance with the codes. This qualification requirement shall be

applicable to the contractor‘s staff as well.

3.26 Licensing of Skill Labor

Licensing of Skilled construction workers, inspectors, supervisors and professionals should

be adopted with provision of appropriate training addressing the requirement of quality

monitoring.

4 Implementation of Codes and Standards

The current practice of implementation of codes and standards is very poor. Particularly, this

is correct since there is no institution that is responsible for monitoring the implementation of

the Codes and the roles and responsibilities of various entities involved are not defined in

context of application of NNBC and NS. Appropriate Institutional Arrangement for

continuity of follow up for upgrading NNBC will be required. NNBC has certain provision

of Water Supply, Sanitation and Plumbing (NNBC208:2003), Electrical Safety (NNBC

207:2003), and Fire Code (NNBC 107:1994) but these codes are seldom used for granting

the Building Permit.

4.1 Water Supply and Sanitation

There is no code related to water supply.

4.2 Electrical Code

Electrical Safety Code (NNBC 207:2003) provides certain guideline for electrical details to

be made. However the need for detailed electrical diagram including wiring details is not

strongly spelt out and monitoring of safety shall be considered. Nepal Electricity Authority

makes certain verification of the house wiring prior to providing connection to the city

supply.

4.3 Fire Safety Code

The Fire Safety Code as provided by (NNBC 107:1994) is limited in application of certain

provisions as fire alarm and other appurtenances. The requirement for design consideration

and selection of building material based on Fire Grading of the Building category is not

included.

4.4 Use of NNBC 205: MRT

The municipality licensed designers widely use these codes for all construction beyond the

limit of MRT for building of larger sizes as well.

Equally, MRT is extensively used for rural construction. It shall be said that this document is

a very useful one but need to be very cautious since the designers in urban areas particularly

are misusing this document and threatening the safety. The minimum size of column of

9‖x9‖ recommended in NNBC is considered inappropriate for construction and LSMC is

adapting 9‖x12‖, and changed the concrete grade from M15 to M20.

It was referred that while better examples of standard typical designs to be made available

for replication where permitted, MRT itself should not be a part of the Bylaws, Codes and

Standards.

5 Review of NNBC

5.1 Review of NBC 000: 1994 State-Of-The Art Design And NBC 105: 1994

Seismic Design Of Buildings In Nepal

5.1.1 General

Seismic design of buildings constitutes the principal component of the building codes. The

purpose is to reduce or mitigate the damage due to future earthquakes. It has been well

recognized that the single most important development in reducing earthquake losses in the

world has been the incorporation of seismic design provisions into the building codes. The

seismic codes of various countries are in a state of continuous evolution in research and

changes in construction practice.

The history of building code and hence the seismic design of buildings in Nepal is at

tender age compared to the same of other countries. The need for national building code in

Nepal was first strongly felt following the substantial loss and damage due to Udayapur

earthquake of 1988. The preparation of the building code was initiated in early nineties and

published officially only in 1994. The general response to the code has been lukewarm

since its inception, and is in a state of model building code rather than a national building

code in terms of legal status.

Substantial advance have been achieved in the knowledge related to seismic resistant

design of buildings and structures during the past 15 years since the publication of the

National Building Code of Nepal. Changes in seismic design provisions in seismic codes

of different countries from 1994 to the present date are many and far reaching in their

impact. Part of the reasons for such changes has been to incorporate the lessons learned

from the devastating large earthquakes. Inclusion of the lessons learnt from 1994

Northridge and the 1995 Kobe earthquakes have been the major highlights of 1997 edition

of Uniform Building Code with a considerable change in 1994 edition of UBC. Since then

the large earthquakes of Gujarat (2001 January), Sumatra-Andaman (2004 December),

Kashmir-Kohistan (2005 October) and China (2007) have resulted into devastating loss

and damage, imparting the new lessons to be incorporated in the next future seismic codes.

The lessons learnt from the past earthquakes, rapid development in the technology and

researches in the area of Earthquake Engineering have resulted into sophisticated seismic

codes in developed countries. The recent editions of National Earthquake Hazards

Reduction Program (NEHRP) Provisions following the custom of updating in a cycle of

three years substantiate the fact. The recommended provisions incorporated in ‗The

NEHRP Recommended Provisions for Seismic Regulations for New Buildings‘ have

increasingly been adopted in recent times by model codes and standards. If in United

States, there is a custom of revising the codes every three years, it may be not that easy in

case of developing countries like Nepal. The revised edition of the Indian standard Criteria

for earthquake resistant design of structures IS 1893(Part 1) 2002 came into light replacing

IS 1893: 1984 only after a period of 18 years. However, it should be recognized that the

updating of design documents like the codes is a dynamic process, and shall be

materialized as soon as possible to further reduce and mitigate the possible losses in future

earthquakes. In view of this, it is urgently needed that the present code on seismic design

of buildings in Nepal is carefully reviewed with an objective of removing any deficiencies,

errors or scope for misinterpretation. Moreover, development of commentaries or

explanatory handbook on the code to explain the provisions with solved examples is of

utmost importance to solicit a favorable response from users.

5.1.2 NNBC 000: 1994 Requirements For State-Of-The Art Design

NNBC 000: 1994 basically describes the preface of the building code preparation and

philosophy behind the need for seismic design of buildings in Nepal. It describes and

advocates for, in general, four different levels of sophistication of design and construction,

namely, International state-of-art, Professionally engineered structures, Buildings of restricted

size designed to simple rules-of-thumb, and Remote rural buildings where control is

impractical. Accordingly, the NNBC 000: 1984 contains four separate parts describing the

requirements for each category of the design sophistication. The categorization of the design

and construction is highly influenced by the typology of buildings prevalent then in Nepal and

appears highly overwhelmed by the fact that the first ever building code should be generous to

accommodate the unsophisticated and un-engineered design. It implies the poor status of

design capability and exposure to building codes and standards. It calls for a need to not only

to revise regularly but also ascertains that the provisions are drafts standards for adoption by

NBSM. The content of NNBC 000: 1994 could have been a set of good guidelines

incorporated in local building regulations or byelaws. Since a national building code also

represents the status and sophistication of design and construction embracing latest research

and technological developments, it should not only emphasize but also concentrate only on the

International state-of-art.

A building code is a set of rules that specify the minimum acceptable level of safety for

buildings and other constructed objects. The main purpose of the building code is to protect

public health, safety and general welfare as they relate to the construction and occupancy of

buildings and other structures. The Building Code becomes the law of a particular

jurisdiction when formally enacted by the appropriate authority. Generally the codes are

meant for regulating building activity which may be recommendatory or mandatory

depending upon the authorities issuing these. Compliance to the building code is

mandatory when it is covered in Building Byelaws, Regulations, Acts, Rules, etc. issued

by the National Government and various regional or local authorities.

Building Codes are generally intended to be applied by architects and engineers, but are

also used for various purposes by safety inspectors, environmental scientists, real estate

developers, contractors, manufacturers of building products and materials, insurance

companies, facility managers, disaster management personals, and others.

The practice of developing, approving, and enforcing Building Codes is different from one

country to another. In some nations Building Codes are developed by the governmental

agencies or semi-governmental standards organizations and then enforced across the

country by the national government. Such codes are the National Building Codes, and they

enjoy a mandatory nation-wide application. In the countries, where the power of regulating

construction is vested in local authorities, a system of Model Building Codes is used.

Model Building Codes have no legal status unless adopted or adapted by an authority

having jurisdiction. In some countries, each municipality and urban development authority

has its own building code, which is mandatory for all construction within their jurisdiction.

Such buildings codes are variants of a National Building Code, which serves as model

code proving guidelines for regulating construction activity. The degree to which national

building codes and standards are enforced by law varies from country to country, as stated in

the Foreword of the Code, however it was intended that its implementation be enforced

through the Parliamentary Bill Act and concerned, local authority by-laws. In the above

scenario, it has become very important to establish the status of the building code. It is to be

noted that Building Byelaws, in relation with Building Codes, are mandatory rules and

guidelines for construction activities, issued normally by governmental agencies or

authorities with jurisdiction. Byelaws reflect the legal status of the document, and are

regulatory in nature. National Building Code or Model Building Code may be included as

an essential part of Building Byelaws; however, building codes may not contain the

byelaws. In view of this the philosophy of various levels of requirements depending upon

the design sophistication are more relevant to the byelaws to be enforced by the central or

local authorities. It is always preferable to maintain the distinct boundaries between

existing building byelaws/building regulations and building codes to avoid the confusion.

The sanctity of the building code, different from building byelaws and building

regulations, and in its turn, the seismic design of buildings shall be retained by focusing on

the international state-of-art.

It is important to understand the expressed or implied purpose of a particular design

document in order to fully appreciate its provisions. Although the basic purpose of any

seismic code is to protect life, the way that this purpose as well as any additional purposes,

presented can provide additional insight into the reasons for the presence of specific

provisions in the body of the document and its intended audience. The document shall be

free, as far as possible, of ambiguous or confusing statements or provisions. The following

paragraph describes some of issues to be resolved under NNBC 000: 1994:

The background of the development of the building code and the philosophy of seismic

design could be reasonably incorporated in the introductory part of Seismic Design of

Buildings or even in that of National Building Code itself. The requirements for the Professionally engineered structures (Part II), Buildings of restricted size designed to

simple rules-of-thumb (Part III), and Remote rural buildings where control is impractical

(Part III) along with minimum design requirements based on the flow chart (Figure 1) shall

be left out for building regulations or building byelaws. The requirements for the

International state-of-art is the main part, based on which the Seismic Design of

Buildings evolves. The need for a separate code on the remaining issues is not

justifiable.

Labeling the Building Code or part of it as draft standards belies the purpose of the

document, and weakens the position of the code executing agencies in the

enforcement of the building code.

Ambiguous statements shall be removed unless a necessary clarification is provided to

avoid the scope for misinterpretation. The return periods mentioned for the onset of

damage of a typical building and for the strength of building as 50 years and 300 years

respectively, in 1.2 Seismic Design under Part 1, need a clarification or rephrasing.

Incomplete sentences in the document of importance shall be avoided. The sentence

starting with ―The basic philosophy for…‖ and ending in blanks, in 1.2 Seismic Design

under Part 1, fails to express the principal objective of the seismic design.

The language and the format of clauses and provisions in a building code deserve a

formal/legal style rather than those of a technical report. The paragraphs following the

subheading 1.3 Other Loads under Part 1 appear like parts of a report with a little

regard for other Nepalese Standards.

Mere referring the Indian Standard Codes of Practice for design in materials like

concrete, steel and masonry does not serve the purpose of popular use and enforcement

of Nepal National Building Code. IS 456: 1978 Indian Standard Code of Practice for

Plain and Reinforced Concrete has been revised into the Fifth revision IS 456: 2000

Indian Standard Code of Practice for Plain and Reinforced Concrete. Similarly the

detailing requirements included in IS 4326: 1993 Indian Standard Code of Practice for

Earthquake Resistant Design and Construction of Buildings have been modified and

incorporated in a separate detailing code IS 13920: 1993 Indian Standard Code of

Practice for Ductile Detailing of Reinforced Concrete Structures subjected to Seismic

Forces. Since the present building code of Nepal is not explicit about which Indian

Standard Codes, referred ones or revised ones, to be adopted, the designers along with

other stake holders obviously will be in dilemma.

Due reference to Nepalese Standards without using the adjective – draft, and without

the background of their development, is most preferable. The Nepalese Standards, such

as for Wind Loads (NNBC 104: 1994), Steel Design (NNBC 111: 1994), Un-

reinforced Masonry (NNBC 109: 1994) and others shall be reviewed and improved, no

matter assistance from which international codes or publications has been derived, so

that these could be treated with respect as Nepal‘s own Standards and essential

components of the National Building Code.

Due weightage needs to be given to international coordination among the standards and

practices prevailing in different countries in addition to relating it to the practices in the

field in Nepal.

5.1.3 NNBC 105: 1994 Seismic Design Of Buildings In Nepal

Background and purpose of the code

The important information regarding the preparation of the code including its history of

development, need of the document development/improvement and the purpose of seismic

design shall be described under Foreword. Due credit shall be given to the documents and

codes, which have been used and referred in the development of the code.

The present form of Foreword needs to be enhanced with changes in terms of content and

description. The name of sub-heading - design procedure and its content stating as the

minimum design requirements for the seismic design of structures do not match; referring just

to the section under the scope does not say any thing about the design procedure nor about the

minimum requirements.

The special emphasis on the need for application of the code in conjunction with IS 4326 –

1993, under sub-heading – Related Codes is not appreciable for two reasons. Firstly, the status

of IS 4326 – 1993 in India has been changed with most of the contents being separately

transferred into newly developed codes. The statement in the para implies that NNBC 105:

1994 can not be used without referring IS 4326 – 1993. In principle, emphasis should be on the

need of developing such basic standards or codes. Alternatively, the relevant provisions shall

be incorporated, separately as clauses, in the seismic design code itself. Naming recent editions

of IS 4326 – 1993 or other relevant national and international codes or documents as reference

materials will be more appreciated. Moreover, details of the Standards, preferably developed

for Nepal, which are necessary adjuncts to the Seismic Design of Buildings in Nepal shall be

listed elsewhere in the code.

The absence of the Commentary, forming an accompanying volume to the code, makes it

difficult to substantiate the requirement of using the code in association with the Commentary

as given under sub – heading- Commentary.

Scope

The requirements presented under the section of scope of the present code sound conservative.

Instead, the scope of the code should be general and broad in terms of seismic load assessment

on various structures and seismic resistant design of buildings. The basic provisions shall be

applicable to buildings, elevated structures, industrial structures, dams, bridges and other

structures. The scope may not include the construction features of those buildings for which

separate standards will have to address.

Terminology

The terms used in the seismic design and their definitions given in the present code should be

extended. Since the code is the sole principal document for earthquake resistant design of

buildings it will be preferable to include basic terms and their definitions related with

Earthquake Engineering in general to shed light on basic seismological aspects, as well as

Earthquake Engineering related with buildings. Basic terms related with damping, modes,

spectra, PGA, importance factor, intensity and magnitude of earthquake, liquefaction,

maximum considered earthquake, normal modes and modal characteristics, seismic weight,

zone factor and others related with basic Earthquake Engineering shall be included. It is also

necessary to incorporate more terms related with building such as base, center of mass and

rigidity, design eccentricity, base shear, bracing systems, lateral load resisting elements,

principal axes, P- effect, storey drift, storey shear, soft storey and others.

Symbols

The symbols used in the present code may be retained with the extension or revision as the

method improved or altered. However, some terms used in the symbols may be changed, for

example, fundamental time period is more suitable than translational period Ti. There is

perhaps a typographical error in meaning the symbol Fp –design seismic force for elements

and components designed in accordance with 8.

General Principles of Design

The general principles described under the present section 3 of the code could be elaborated

with the important features of seismicity and basic assumptions of seismic design.

It is necessary to include the general principle adopted regarding the ground motion, its

features in relation with the earthquake source characterizations including the sizes of the

earthquake.

It will be favorable to describe the seismic design approach adopted in the code. The generally

accepted principle of seismic resistant design of buildings is that structures should be able to

withstand minor earthquakes without damage, withstand moderate earthquakes without

structural damage but with some non-structural damage, and withstand major earthquakes

without collapse but with some structural as well as non-structural damage. These widely

quoted objectives, however, are unstated in many codes including the current NNBC 105:

1994. Instead, the principal objectives are stated, for example, the Uniform Building Code

UBC 1997 states an overall objective of safeguarding life or limb, property and public welfare.

Although the definitions of minor, moderate and major earthquakes are variable, they

generally relate to the life of the structure, and the consequences of failure. The major

earthquake level defined in most of the codes of the world has a recurrence interval of 475

years, which corresponds to a 10% probability of exceedence in 50 years that is commonly

accepted to be the expected life of a building. The corresponding service level earthquake for a

typical building would have a recurrence interval of 10 years and a 99.3% probability of being

exceeded in 50 years.

There is also a need to mention about the design approach in relation with consideration of

lateral force in each of the two orthogonal horizontal directions, and approach regarding

consideration of earthquake load in vertical direction. It shall also include the approach and

corresponding provision regarding simultaneous occurrence of wind or flood, soil-structural

interaction and change in usage of the building.

Design Methods and Load Combinations

There must be a valid logical reason for need of Limit State Method of design for reinforced

concrete design and recommending Working Stress Method for other structural materials. At

this juncture of improvement, it will be preferable to explore the design methods available and

recommended in other codes and adopt the design method most appropriate for the country. In

general, most of the countries have adopted Limit State Method or Strength Method replacing

Working Stress Method for Concrete as well as Steel, the two principle structural materials.

The provision regarding the increase in allowable soil bearing pressure by up to 50 percent

when earthquake forces are considered along with other design forces according to 4.3 of the

present code may be too un-conservative and ambiguous in application. Elaboration of the

clause is required about in what condition 50% increase can be considered, and in what

condition lower values, which are to be mentioned, of increment can be considered. IS 1893

(Part 1) : 2002 recommends the increase in allowable soil bearing pressure from 25 to 50%

depending upon the soil type (hard, medium or soft ) and the type of foundations (piles, raft,

combined, isolated and well).

The design load combinations included in the present code for Working Stress Method as well

as for Limit State Method seriously require reworking. It is well recognized that the load

factors, recommended are based on the reliability levels assumed in the structures. For

example, it appears too un-conservative to have load factor for dead load as 1 and for live load

1.3 in case of Nepal. The uncertainties due to non-uniformity of materials, workmanship,

quality control seem to be ignored in the load factor for dead load. The uncertainties in

overloading is covered by maximum 1.3 may not be practical in the condition of Nepal. IS 456

: 2000, for example, considers 1.5 for both the dead load and the live load. Similarly the

maximum load factor value for seismic load considered is just 1.25, both in combination with

0.9 times dead load, as well as in combination with dead load and 1.3 times live load. The

value of 1.25 is too low in view of the large uncertainties involved in assessment of the

seismic load. Furthermore, the recommendation for adoption of partial safety factors as per

Table 12 of NNBC 110: 1994 contradicts the provision of 4.5 of Seismic Design Code.

Method of Seismic Design

The present seismic code recommends two methods of earthquake analysis, namely, Seismic

Coefficient Method and Modal Response Spectrum Method.

The bulk of seismic resistant buildings are designed using equivalent static lateral forces to

represent the effects of ground motion due to earthquake on buildings. It is from the

assumption that equivalent static forces can be used to represent the effects of an earthquake

by producing the same structural displacements as the peak earthquake displacement response.

The application of this method is limited to reasonably regular structures. The present code

restricts the use of this method for structures up to 40 m height, and should also mention the

condition of regularity.

The dynamic analysis shall not be confined to the response spectrum method. There must be

an optional provision for Time History Analysis also. The conditions for need of using Modal

Response Spectrum Method (Dynamic Analysis) are listed, which are basically related with

irregular configuration. Due to absence of definition and classification of irregularity, the users

of the code will be confused. It is desirable to include clauses that define and describe different

types of irregularity (horizontal, vertical, stiffness, mass, geometric and others). By such

definitions a clearer picture and effect of soft storey and weak storey will be available.

The formula for determination of seismic coefficient has been changing in the seismic codes of

the world. However, the base shear due to ground motion has all the time been the product of

the seismic coefficient and the mass of the structure. The principal code factors used in

deriving static lateral forces, for a long time, have basically been:

Z A numeric value representing the seismic zoning

I An importance factor representing the importance of the structure,

especially in terms of use following a major earthquake.

C A factor representing the appropriate acceleration response spectrum value.

S A factor representing the effect of local soil conditions on the spectral

response of the ground

W The mass of the structure, including an assessment of live load

K A factor representing the performance of the structure depending on the

brittleness or ductility of the structure These values are combined in general

form for base shear:

V = ZICKSW

This formula for base shear has been for a long time popular. However in course of

evolution the formula for the seismic coefficient has been changing. The formula for the

seismic coefficient presented in the present NBE 105: 1994 considers all the above factors

except S-the factor representing the effect of local soil conditions on the spectral response

of the ground. This effect has been considered, like in other codes, in the response spectra

drawn for different (basically three) types of soil. Thus the expression for the seismic

coefficient is given in equation 8.1. Similarly, the equation 8.2 for the expression for the

design response spectrum, in which the ordinate of the basic response spectrum for the

natural time period, is multiplied by ZIK.

It has been a trend in the codes of the world to drop the performance factor K and replace it

by reciprocal of R, response reduction factor, a factor dependant on the building type and

its ductility level. The adoption of the response reduction factor leads to a realistic values

of acceleration from which the design forces are obtained by dividing the elastic forces by

it. It implies that the design force is much lower than what can be expected in the event of

a strong earthquake (Jain 2003).

The replacement of the factor K by the factor 1/R may result into a logical estimation of

the seismic coefficient, and alternate expressions derived in recent editions of codes or

documents like NEHRP shall be given a thought for the new edition of the code.

Computing dynamic response instead of using static forces is becoming increasingly

common as higher powered computing facilities are being available in design offices.

Since there is no restriction of building height and irregularity the dynamic analysis

appears to be simpler in application and yields more logical and accurate results. However,

special care shall be taken into consideration about conservative provision in some

international codes. Some codes require checking of the dynamic analysis results by

seismic coefficient method. Some documents like IS 1893 (Part 1) : 2002 require

comparing the base shear with the base shear calculated using the fundamental time period

calculated using the empirical formula recommended for static approach, and if the base

shear from dynamic analysis is less than the base shear calculated using the time period

from the empirical formula, all the dynamic responses shall be up-scaled multiplying by

the ratio of the two base shears. It again implies the dominance of the seismic coefficient

method over the dynamic analysis.

Seismic Hazard Level and Response Spectrum

Estimate of the design ground motion is the most important and complicated part of the

seismic design code development. Estimates of the design ground motion are necessarily

controversial and uncertain. It is more important to the structural designer that this is

understood than for him to attach some particular significance to any ground motion

parameter used in his design. However there is a strong argument for conservatism in the

assessment of ground motion input, and the use of high confidence level.

NNBC 105: 1994 does not present any elaborate information on the seismicity of the

country. It would be favorable to include at least maps showing epicenters of past

earthquakes, principle tectonic features, geological features including principal lithological

groups, and seismic zones, all of which are well documented by the Department of Mines

and Geology, Nepal. Pandey et al. (2002) has presented seismic hazard map of Nepal as a

result of probabilistic seismic hazard analysis The document presents the contour of

seismic hazard at the bedrock of Nepal for a return period of 500 years, indicating 10%

probability of exceedence in 50 years.

The design values of ground motion parameter such as Peak Ground Acceleration (PGA)

for different regions of the country are presented either in a tabular form (GB 50011-2001)

or attaching relevant maps like in IBC 2006 in the codes. It is necessary to do the same in

NNBC 105: 1994 also since the seismic hazard for the code was determined based on the

probabilistic seismic hazard analysis. The seismic codes adopting probabilistic approach of

hazard estimation use the hazard levels in terms of Maximum Considered/Capable

Earthquake (MCE) as in NEHRP (2003) and IBC (2006), and Design Basis Earthquake

(DBE) as in ATC (1978) and UBC (1997). The MCE and DBE represent 2% probability of

exceedence in 50 years with a return period of 2500 years and 10% probability of

exceedence in 50 years with a return period of 475 years respectively.

The seismic hazards considered in earlier editions of NEHRP and UBC 97 (1997) had a

recurrence interval of 475 years (Design Basis Earthquake) corresponding to a uniform 10

percent probability of exceedance in 50 years, which is commonly accepted to be expected

life of a building. The NEHRP(1997) and IBC2000(2000) had changed the Design Basis

Earthquake(DBE), and since then have been using the Maximum Considered Earthquake

(MCE) to represent the seismic hazards in the provisions.. The MCE represents the seismic

hazard that has a recurrence interval of 2500 years corresponding to a uniform 2%

probability of exceedence in 50 years. The design earthquake according to the provisions

of NEHRP(2003) and IBC 2006 (2006) is two-thirds of the MCE. Comparison of the

provisions of 1994 or older editions with 1997 or later editions of the NEHRP Provisions

reveals that, a structure designed by the 1994 or older editions of NEHRP Provisions is

believed to have a low likelihood of collapse under an earthquake that is one and one-half

times (reciprocal of two-third) as large as the design earthquake of those documents. The

same change has taken place from UBC 97 (1997) to IBC 2000 (2000). This major change

in association with other provisions indicates the newer versions of the documents tend to

be more conservative.

The seismic loading in NNBC 105: 1994 is set at a seismic hazard level having a return

period of 50 years, which corresponds to a probability of exceedence less than 45% in 30

years, which had been estimated as the economic life of a structure in Nepal, as presented

by Beca Worley International et al.(1993), The document as well reveals that the seismic

hazard level was set to be at a level approximately equal to that defined in the Indian

Standard, that is, IS 1893: 1984. The design earthquake level set hence is too un-

conservative and strongly needs a major revision for the following reasons:

i. The service life of buildings in Nepal estimated as 30 years is far from reasonable,

instead it must be 50 years.

ii. It is unfair to set the seismic hazard level for Nepal heavily banking upon the

earthquake level stipulated in IS 1893: 1984, which has already been revised into IS

1893 (Part 1): 2002 with a different value of design earthquake value. The Indian

Standard has yet to adopt probabilistic format of seismic hazard analysis.

iii. The provisions in the present code have been developed in reference with mainly low

rise buildings with short natural periods, where as long period structures are

increasingly becoming prevalent.

iv. The seismic design lateral load calculated for short period structures as 0.08, when

compared with the basic horizontal seismic coefficient for zone V of IS 1893: 1984,

found the same as 0.08. But the value according to the revised IS 1893 (Part 1): 2002

will be 0.09 against 0.08.

The response spectra and the zoning factors largely depends on the design earthquake

levels, and hence will be different as the seismic hazard levels change.

The broad classification of soil conditions into three types is universally accepted.

However, the definition and requirements of each type of them shall be more practical and

recognizable.

Static Method (Seismic Coefficient Method)

The seismic base shear V along any principal direction is determined by the expression:

V = Cd Wt

In which Cd is the design horizontal seismic coefficient, and Wt is the seismic weight of the

building. However, the expression given by equation 10.1 is not supplemented with what

stands for the notation Wt . Moreover, it requires the definition of the seismic weight of the

building. There is also a need to describe how the seismic weight of the building is

calculated in terms of seismic weight of floors, which has to be referred, although briefly

introduced under the section 6 Seismic Weight. It should further be elaborated with the

rules for lumping of weights.

The distribution of the design base shear along the height of the building is carried out in a

linear manner, that is, the design lateral force at floor level i is calculated by:

Fi = V Wi hi/ΣWi hi

The Indian Standard IS 1893 has long been adopting the parabolic distribution,

corresponding to which the design lateral force, equivalent to IS 1893 (Part 1):2002, at

floor level i is calculated by:

2

1

2

ii

n

i

iii

hW

hWVF

Both of the above distributions are at the extremes. The linear distribution is true for

basically stiff structures having a natural period of 0.5 seconds or less (approximately for

up to 5 storeys of the building). The parabolic distribution is applicable basically for

flexible structures having a natural time period of 2.5 seconds (approximately for 25

storeys and more of the building).

The distribution of the horizontal forces over the height of a building is generally a quite

complex because these forces are the result of superposition of a number of natural modes

of vibration. The relative contributions of these vibration modes to the total forces depends

on a number of factors, which include shape of the ground motion response spectrum,

natural periods of vibration of the building, and the vibration mode shapes, which in turn

depend on the mass and stiffness distribution over the height of the building. Based on it,

ATC 3-06 (1978) has provided the reasonable and simple formula to obtain the horizontal

earthquake force distribution in buildings with regular variation of mass and stiffness over

the height as follows:

k

ii

n

i

k

ii

i

hW

hWVF

1

in which, k is an exponent related to the building period as follows:

For buildings having a period of 0.5 seconds or less, k = 1.

For buildings having a period of 2.5 seconds or more, k = 2.

For buildings having a period between 0.5 and 2.5 seconds, k may be taken as 2 or may be

determined by linear interpolation between 1 and 2.

In view of the changing characters of the buildings, increasingly departing from the low

rise situation, the linear distribution provision in the code will be again un-conservative,

and hence needs a change. It is to note that the American codes have been adopting the

distribution formula developed by ATC 3-06 (1978).

The provision regarding the direction of forces under sub-heading 8.2.1 shall be rewritten

to clarify to the effect that the structure shall be designed for design earthquake load in one

horizontal direction at time, indicating the design earthquake load will not be applied

simultaneously in both of the orthogonal directions.

The design eccentricity provision should have been provided together with the clause on

the horizontal shear distribution or under Torsion. The design eccentricity, ed is

recommended to be calculated depending upon the value of ec ( eccentricity between the

locations of the center of mass and the center of rigidity) in relation with b, the maximum

dimension of the building perpendicular to the direction of the earthquake force. Three

separate conditions and corresponding values to be used or calculated are presented. The

design eccentricity is required to calculate the design torsional moment to consider its

effect in the distribution of lateral forces at each level. The purpose of the provision on the

design eccentricity would have better been served by a clause on Torsion to the effect ―The

distribution of lateral forces at each level shall consider the effect of the torsional moment

resulting from eccentricity ec between the locations of the center of mass and the center of

rigidity‖. It should be followed by a complimentary clause on Accidental torsion, to the

effect ―In addition to the torsional moment, the distribution of lateral forces also shall

include accidental torsional moments, caused by an assumed displacement of the mass

each way from its actual location by a distance equal to 5% of the dimension of the

structure b, perpendicular to the direction of the applied forces. Alternatively, The design

eccentricity would be algebraic sum of the factored eccentricity and the accidental

eccentricity each way. Accordingly, the expression for the design eccentricity for ith

floor

would be, assuming 1.5 as the factor for the eccentricity:

edi = 1.5 eci ± 0.05 bi

Dynamic Method (Modal Response Spectrum Method)

equation for dyanamic Method

The provisions presented in the present code are not adequate. There is a need for clauses

for free vibration analysis to obtain the natural periods (T) and mode shapes (φ). The

present provision for the numbers of the modes to be considered in 11.2 needs elaboration

including explanation how to check if the 90% of the mass is participating or not. It shall

be done by introduction of formulae along with definitions of modal mass and modal

participation factors. There are serious lapse of provisions for modal combination methods,

methods for determination of design lateral forces at each floor in each mode and due to all

modes considered, and also expressions for storey shear forces in individual mode and due

to all modes considered.

The para 11.3.1 mentions about need to use an established method for combination of

modal effects. An ambiguous word like established method shall be avoided and replaced

by the name of the method/s to be applied. The definition of closely spaced modes as given

in para 11.3.3 is incorrect. Closely spaced modes are defined as those of its natural modes

of vibration whose natural frequencies differ from each other by 10 % or less of the lower

frequency, not if their frequencies are within 15%.

Deformations

The primary clause for deformation due to earthquake forces is the storey drift limitation,

which shall not exceed 0.004 times the storey height. The sense of this limitation may be

implied from the provision given under 9.2.2. For the purpose of displacement

requirements only, the seismic forces obtained from the fundamental time period of the

building by static or dynamic approach may be used. The provision under 9.1 shall be

applicable for the separation between two adjacent buildings or two adjacent units of the

same building. The separation must be provided by a distance equal to the sum of the

calculated storey displacements multiplied by 5/k or by R, if the performance factor k is

replaced by response reduction factor R. rewritten as for the separation. It shall further be

supplemented by the provision that if the floor levels of the two adjacent units or buildings

are at the same elevation levels, the factor 5/k or by R may be further replaced by 10/k or

R/2 respectively. Accordingly it is preferable to rearrange the sub-clauses under this

section.

Requirements for Other Components and Elements

The provisions under section 12 shall elaborate, beyond the general statements, how the

requirements are achieved. This section also shall present provisions for important

components like foundations, projections and other parts of the buildings.

5.2 Review of NNBC 101, 102, 103, 104, 106, 108, 109 (Loads, Occupancy, Site

Consideration, Unreinforced Masonry)

5.2.1 NNBC 101:1994: Materials Specifications

This standard deals with the requisite quality and effectiveness of construction materials used

mainly in building construction.

The code requires the use of materials confirming to NS or IS or any other approved

standards agency to satisfy this Standard which is referred to IS. This provision has made the

code redundant and not useful.

A list of such Nepal Standards and Indian Standards is provided for reference.

The use of appropriate, adopted or new materials is encouraged, provided these materials

have been proven to meet their intended purposes provided that these materials comply with

the requirements of this code. But the code has no reference to any criteria (better in quality,

strength, effectiveness, fire resistance, durability, safety, maintenance and compatibility) that

required to be checked.

If recycled /used materials meet the requirements of the standard, they may also be used.

The storage requirement for all building materials is mentioned in a vague way and do not

give any methods or reference to any guidance or Manual so that could provide methodology

of storage including limiting duration of storage. It requires to assure that during storage the

properties of materials should not be deteriorated or lossed.

The code does not cover the health hazard or Fire Hazard induced by use, transport, storage

or handling or hazard to urban life. A lot of sales depot operated in the cities do not consider

or comply to any requirement of reduction of health hazard which is one of the key objectives

of any Building Codes. Lot of traffic accidents are induced by storage of materials at roads,

transportation, and use at public places and roads. While updating, the safety and health

hazard issues induced by building materials should be considered.

The terminology Nepal National Building Codes series NNBC and Nepal Standards NS are

referred with confusion. Some where NNBC is referred as Nepal Standard which is

nominated with series 500.

5.2.2 NNBC 102:1994: Unit Weight of Materials

This Nepal Standard for unit weight of Materials adopts the Indian Code IS:875(Part 1)-1987

code of Practice for Design loads ( Other than Earthquake) for building and structures, Part 1-

Dead loads-Unit weight of building materials and stored materials.(second revision).

Since the table of unit weight of material not provided in the code, the code is not convenient

to use. Unit weight of materials is provided in Nepal Standard, so it is better to use the table

of unit weight of material from NS.

5.2.3 NNBC 103:1994: Occupancy Load (Imposed Load)

This Code (or Standard?) is nothing more than statement of justification for adoption of IS

Code and hence is not useful fro practical purposes.

This Nepal Standard for Occupancy Load adopts the Indian Code IS:875(Part 2)-1987 code

of Practice for Design loads ( Other than Earthquake) for building and structures, Part 2-

Imposed Load.(second revision).

The occupancy classification should be provided. Table for the imposed floor load for

occupancies should be provided to make the convenient for user.

In Nepal Standard NS , different tables such as table1-Imposed floor loads for different

occupancies, reduction in imposed loads on floors, table 2- Imposed loads on various types

of roofs, table 3- horizontal loads on parapets, parapet walls and balustrades are provided

which can be used in NNBC 103:1994 to make the independent code.

Uniform live loads. The live loads used in the design of buildings and other structures shall

be the maximum loads expected by the intended use or occupancy but shall in no case be less

than the minimum distributed loads required by provided table.

Partition loads. In office buildings and in other buildings where partition locations are

subject to change, provision for partition weight shall be made, whether or not partitions are

shown in construction documents, unless the specified live load exceeds 80 pound per square

foot (3.83 kN/m2). Such partition load shall not be less than a uniformly distributed live load

of 20 pounds per square foot (0.96 kN/m2).

As per occupancy classification, egress must be adequate for the uses to which it will be put.

Changing use of occupancies

As we know in Nepal, the uses of building are changed from one occupancy classification to

another occupancy, for example from residential to school or from a hotel to Super Market.

In such cases the occupancy load will be changed. It's an important aspect of any building

design. Occupancy load calculations are made as per different occupancies. This is very

dangerous for the overall safety of the building unless such changes are justified by structural

analysis. The Code requires to impose categorical prohibition on such change in use of

buildings from one occupancy classification to another.

5.2.4 NNBC 104:1994: Wind Load

This Nepal Standard on ―Wind Load‖ comprises the Indian Standard IS:875(Part 3)-1987

code of Practice for Design Loads ( Other than Earthquake) for building and structures

(Second Revision) with amendments to ensure the requirements of Nepalese context,

particularly wind zoning map of Nepal.

The available wind data is inadequate both in terms of spatial distribution and duration.

Modern wind design codes are based on the peak gust velocity averaged over a short interval

of about 3 seconds that has a 50 year return period. The available Nepalese wind data is

insufficient and irrelevant to prepare wind zone map.

On the base of wind velocity, Nepal has been divided into two regions: (a) The lower plains

and hills and (b) the mountains. The first zone generally includes the southern plain of Tarai,

the Kathmandu valley and those regions of the country generally below the elevation of 3,000

metres and the second zone covers all the areas above 3,000 metres.

For the Nepalese plains continuous with Indian plains, a basic velocity of 47m/s has been

adopted. In the higher hills, a basic wind velocity of 55 m/s is selected.

Following observations on the Code are made:

- Map of Nepal showing basic wind speed is missing;

- Wind data table is missing (even though is is mentioned on page 2 second paragraph

―Available wind data collected during the preparation of code is presented in appendices

NNBC 104:1 to 5‖);

-In the present code, some amendments to IS: 875 (Part 3)- 1987 was made to prepare NNBC

104: 1994. The code is mostly replacement or editing of terminology e.g. addition, deletion or

replacement of words.

This type of amendments has made the code very uncomfortable for use. The Nepal Standard

NS 500 provides the map of Nepal showing basic wind speed and tables for the different

factors. Nepal National Building Code needs to provide detailed data and documentation in

the code itself so that it becomes convenient for the user.

Some comments and method of estimation of Wind Speed, Basic Wind Speed, Design Wind

Speed, Design Wind Pressure based on altitude and building typology are provided in

Appendix-5. The basic Wind speed is derived as a combination of probability factor (risk

coefficient), terrain, height and structure size factor, and topography factor. The Design Wind

Pressure is derived as a function of design wind speed, Wind directionality factor, Area

averaging factor, and Combination factor.

The Russian Code and Standard (SNIP) recommends that wind load on tall building shall be

estimated as the sum total of average and pulsation excitations.

The Nigerian standard code of Practice (NSCP I) recommend to calculate Design wind load

as a function of nominal wind pressure, nominal wind velocity shape factor, and pressure

coefficient.

Reference to these codes is provided for convenience at later stage while updating the codes.

5.2.5 NNBC 106:1994: Snow Load

This code ―Snow Load‖ comprises the Indian Standard IS: 875 (Part 4) 1987: CODE OF

PRACTICE FOR DESIGN LOADS ( OTHER THAN EARTHQUAKE ) FOR BUILDINGS

AND STRUCTURES (second revision) along with new improvements and amendments to

ensure the requirements of the Nepalese context.

In this code, 0.1 to 0.3.2 has been deleted from the original version to match the code with the

Nepalese lifestyle. The added revisions are related to snow load in the northern snow-covered

districts like Dolakha, Darchula, Bajhang, Humla, Mugu etc. The country is divided into five

categories based on the physiographic regions. Of these five physiographic regions, the Tarai,

the Siwaliks and the middle mountains do not experience snow fall. High mountains get snow

two or three months of a year. Though the Code has considered the Middle mountain area as

―no snow fall zone‖, these areas had experienced snow fall sometimes. This fact has to be

taken care in code updating, particularly for the areas within and around Kathmandu Valley.

Detailed meteorological data should record these facts for more reliable updating of the code.

The High Himalayas always have snow cover throughout the year.

At high altitude in the North of Himalayas, flat roofs are built with mud placed over timber

planks or split pieces of wood. A slope is not provided because the wind speed is high and the

rainfall is sparse. Only a nominal slope that is just enough to drain the melted snow and rain

water. Snow is accumulated on the roof and the narrow space between the adjacent buildings.

Snow accumulated on the roof is removed manually.

No historical snow data exists. The Snow and Glacier Hydrology have just recently started to

collect data in higher region. Snow parameters as Depth, density and water equivalency are

monitored. However, the data obtained from the projects is far less than that of the verbal

inquiry. So, the concerned personnel and institutions are being requested to collect data from

in-depth studies and from inquiries of knowledgeable people of the locality.

Appendix-5 contains various data related to Snow Load such as:

Snow Load in Roof

most favorable roof

Comparison with other codes

As per National Building Code of Canada 1990, the snow load on roof is analysed with

consideration of various factors as ground snow load associated rain load factor, roof snow

load, factor, wind exposure factor and accumulation factor. The Canadian Code considers

snow distribution factors on various types of roofs which can be applied universally with

reliability and the only need would be to adjust the factors detail with local experience.

Some properties of snow loading

A careful assessment of the snow load is required to avoid both unnecessary construction cost

and undue risk of failure. Snow loads on roofs vary widely according to geographical

location, site exposure and shape of the roof.

Snowflakes of falling snow consist of ice crystals with their well-known complex pattern.

Owing to their large surface area to weight ratio they fall to the ground relatively slowly and

are easily blown by the wind.

Freshly fallen snow is very loose and fluffy, with a specific gravity of about 0.05 to 0.1

(1/20th

to 1/10th

of water). Immediately after landing, the snow crystals start to change: the

thin, needle-like projections begin to sublime and the crystals gradually become more like

small irregularly shaped grains. The specific gravity of snow as a result of settlement after

few days would usually increase to about 0.2. This compaction further increases and specific

gravity would be about 0.3 after about a month even at below-freezing temperatures. Longer

periods of warm weather as well as rain falling into the snow (a possibility that must be

included in proper design loads) may increase this density even further.

As a simple rule for estimating loads from snow depths, the specific gravity can be

considered to be about 0.2 to 0.3.

Accumulation of Snow on Roofs

In perfectly calm weather, falling snow would cover roofs and the ground with a uniform

blanket of snow. If this calm continues, the snow cover would remain undisturbed and the

prediction of roof loads would be relatively simple; the design snow load could be considered

uniform and equal to a suitable maximum value of the ground snow load.

Truly uniform loading conditions, however, are rare. In most regions snowfalls are

accompanied or followed by winds, and the snowflakes, having a large surface area than their

weight, are easily transported horizontally by the wind. Consequently, since many roofs are

well exposed to the wind, little snow will accumulate on them.

Over certain parts of roofs, the wind speed will be slowed down sufficiently to let the snow

"drop out" and accumulate in drifts. The drift snow loads could be grouped into following

categories:

(a) Lean-to roofs, i.e. roofs situated below an adjacent higher roof, are particularly

susceptible to heavy drift loads because the upper roof can provide a large supply of snow.

Canopies, balconies and porches also fall into this category and the loads that accumulate on

these roofs often reach a multiple of the ground load depending mainly on the size of the

upper roof. The distribution of load depends on the shape of these drifts which varies from a

triangular cross-section (with the greatest depth nearest to the higher roof) to a more or less

uniform depth.

(b) Flat roofs with projections such as penthouses or parapet walls often experience

triangular snow accumulations that reach the top of the projections on the building, but

usually the magnitude of the load is less than in category (a).

(c) Peaked and curved roofs subjected to winds at approximately right angles to the ridge

provide aerodynamic shade over the leeward slope. This sometimes leads to heavy

unbalanced loads, since most of the snow is blown from the windward slope to the leeward

slope, producing loads that exceed the ground load on occasions. Curved roofs show similar

or even more unbalanced distributions (little snow on top and heavy snow near the base of the

arch).On the other hand it is true that many small peaked roofs on residences, in exposed

areas, usually (but not always) accumulate little snow compared with that on the ground.

Redistribution of Load

Redistribution of snow load can occur not only as a result of wind action. On sloped roofs

there are two problems connected with the melting of snow at temperatures slightly below

freezing. Firstly, melt water can refreeze on caves and cause high ice loads (also water back-

up under shingles). This can at least partly be solved by taking steps to, decrease the heat loss

from the upper parts of the roof. Secondly, if a roof slopes and drains on to a lower one, melt

water sometimes accumulates by refreezing on the lower roof or it is retained in the snow.

Since flat roofs in general do not provide as good drainage as that naturally obtained with

sloped roofs, snow and ice will remain on flat roofs longer than on sloped roofs. On large flat

roofs of industrial and commercial buildings, heavy loads are observed near projections such

as air ducts (which sometimes act like snow fences in retaining snow). When this snow melts

it sometimes drains into the lower areas in the centre of bays (i.e. areas of maximum

deflection) because usually the drains are located at columns (high points). This redistribution

of load causes further deflection and can lead to a very dangerous situation.

Failures due to Snow Load

The number of building failures resulting from snow load is relatively high in Canada.

Admittedly many of them occur in older and substandard constructions and should thus be

attributed to faults of construction rather than to the snow load. Collapses occur most

frequently in older buildings, farm buildings, and cottages as well as in some community

buildings such as arenas built with a minimum of funds and professional supervision. Partial

failures, however, occur fairly frequently in those parts of roofs that accumulate high loads

from drifting, for example, porches, canopies and lean-to roofs. These partial failures indicate

the need for better design. Although many failures are probably averted each winter by the

removal of snow, this fact should never be relied upon and should never be used as a reason

for a reduction in the design load.

Responsibility of Designer

Code requirements for snow loads must necessarily be rather general, and consequently the

designer should not apply the loads given in the Code without considering the effects of the

shape and exposure of the roof. The designer should, therefore, consider in each case the

building site, size and shape, where drifts are likely to occur on the roof drainage, and so on.

5.2.6 NNBC 108: 1994 Site Consideration

This document sets out some of the factors to be considered during site selection for

buildings in order to minimize the risks to the buildings from both normal and seismic load

conditions. It also outlines the fundamental requirements for site investigation for the

foundation design of buildings.

Site consideration has been made for determining the potential of settlement, fault rupture

hazard, liquefaction, landslides and slope instability of basic general concept. Necessary

mitigation measures should be taken to minimize the potential risks.

The Code very appropriately states that an appropriate level of site investigation and formal

reporting of the design process should be carried out and shall be incorporated in the permit

application documents for the State of Art Design and engineered buildings of all categories

and for mandatory rules-of-thumb and/or advisory guidelines as an indication of good

practice and apply same as appropriate. However, this provision was never materialized and

application of Buildings in Building permit Process was not incorporated.

For site investigations, the basic questions given to address are:

- Is there any danger of inherent natural susceptibility of the land to the process of sliding

and erosion?

- Will the construction adversely affect the existing conditions and trigger landslide, erosion,

land subsidence, pore pressure generation due to blockage of or otherwise the sub-surface

flow of water; will the construction adversely affect the water table?

- What will be the extent of settlement of the building?

- Is the sub-surface capable of taking the load due to the proposed construction?

- Is there any other natural/geological process likely to threaten the integrity of the building?

- What are the possible engineering solutions for ensuring stability of the building

foundation in view of the identified condition?

Answering these questions will make necessity of additional site investigation including

subsurface exploration, in-situ and laboratory testing, geophysical surveys and testing,

probing etc.

The extent of site exploration depends upon the geological and geomorphological nature of

the terrain, and on the importance of the building.

The depth of exploration is based on the geological conditions at the site e.g. the depth and

type of subsurface soil, depth of weathering, depth of ground water fluctuation, depth of

frost action etc.

The code leaves the answers or requirements for liquefaction susceptibility, determination of

allowable bearing pressure and foundation design to the designer to follow the good

engineering practice.

Again, this allows the designer to use other codes making the provisions of this code

redundant.

5.2.7 NNBC 109: Masonry (Unreinforced)

NNBC 109:1994 covers the structural design aspect of unreinforced masonry elements in

buildings. It also deals with some aspect of earthquake resistant design of buildings.

Reference to seismic zoning, seismic coefficients, important factors and performance

coefficients are adopted as per NNBC 105-94 Seismic Design of Buildings in Nepal.

The Code is fundamentally based on Indian Standard IS:1905-1987 Code of Practice for

Structural Use of unreinforced Masonry (Third Revision).

The materials used in masonry construction are taken in accordance with NNBC 101-94

Material Specification and masonry units as per NS 1/2035 Brick Masonry.

The code provides minimum requirements for the structural design and construction of

masonry units bedded in mortar using both allowable stress design as well as limit state

design (strength design) for unreinforced as well as reinforced masonry. The topic on

strength design is a new addition to the previous edition of this code (ACI 530-99/ASCE 5-

99/TMS 402-99). In strength design, more emphasis is laid on reinforced masonry than

unreinforced masonry. An empirical design method applicable to buildings meeting specific

location and construction criteria is also included.

The review has considered the provisions made in various international codes as

International Building Code, Euro Code 5, New Zeeland Standards, Indian Standard and

British Standard. Various methods used by these codes were reviewed and the design

methods were compared. A detailed account of these comparisons is provided in Appendix-

5.

The most important concerns as load combination and loading factors are no where indicated

in the code.

Among the codes studied, only the New Zealand Standards contains provisions on ductility

of masonry structures. Regarding shear, it contains provisions on shear friction

reinforcement and also considers the case when masonry members are subjected to shear and

flexure together with axial tension.

IS:1905-1987 provides a semi-empirical approach to the design of unreinforced masonry.

The masonry codes of other countries provide detailed provision for the design of reinforced

masonry members.

5.3 Review of NNBC: 107 (Fire Code)

5.3.1 General

Fire Hazard in Nepal is one of most common feature of disasters. Mostly during the dry

season in Nov – June, several fire disaster events were reported. According to Judha Varuna

Yantra, the oldest and only public fire-fighting unit in Kathmandu, there is one fire incident

every day, causing irreparable damage to life and property.

The reasons of these fire incidents could be attributed to various reasons covering from a)

deficiencies in settlement planning, b)lack of preventive measures, c) lack of fire resistant

construction, d) mishandling of inflammable substances, e) lack of awareness on fire hazard,

f) criminal activities, g) lack of institutional arrangement to deal implement fire protection

policies, h) Lack of Safety code on use of electricity, gas, fuel, and i) lack of assessment of

fire safety of buildings and premises in urban areas and industries.

The rapidly growing urbanization process in Nepal has created environment for over 132

settlements to be recognized as emerging towns or new municipalities which means that the

rate of urban development including infrastructure will be rapid calling for enforcement of

Urban Development bylaws and National Building Codes, and capacity building of the new

municipal administration.

5.3.2 Main Objectives and Purpose of Building Codes

The main objectives of fire safety design of buildings should be:

Assurance of life safety, protection of property and continuity of operations or

functioning

Building awareness among the designers for recognition of the type of danger posed by

each component of building and allows him to incorporate effective counter-measures,

and

To confine a hostile fire to a room or area of its origin.

The purpose of the Fire Code is to provide minimum design regulations to safeguard life,

property, and public welfare and to minimize injuries by regulating and controlling the

design, construction, use of new materials as plastics, use and occupancy, location and

maintenance of all buildings and structures within the jurisdiction and certain equipment

specifically regulated herein. This has brought new fire and life safety challenges.

5.3.3 Compliance to the Fire Code of Nepal

The Fire Safety Code of Nepal (NNBC 107) was introduced in 1994 but not much experience

has been gained from this code since the code has hardly been practiced and none of the

building permits issued so far was subject to the compliance of Fire Safety Code.

5.3.4 Major Drawback

The major drawback of the fire code is that the code was not been integrated into the

Building Bylaws governing the Building Permit procedures followed by the Municipalities

and the municipalities have not been institutionally reformed to take over the functions

related to Fire Code.

5.3.5 Requirement of Fire Safety in Building Codes

The Fire Safety Code of Nepal National Building Code (NNBC 107) has made certain limited

provisional recommendation on Fire Safety and covers ordinary buildings only. It deals only

with the minimum requirements of limited provisions of a) Fire Places, b) Fire Extinguishers,

c) Storage of Water for Fire Extinguishing, d) Need for demarcation of fire zones, e) General

Requirements for Provision of proper access, wide doors, fire escape ways –exit doors, fire

escapes for buildings with 5 storeys and higher, fire stairs, Open Space, Access to a Building,

provision of Lightning Arresters/Conductors.

The Indian codes IS 1641 to IS 1648 have substantial coverage of various issues of Fire

Safety, but it cannot be considered as comprehensive and adequate for warrantee of Fire

Sefety of Buildings and settlements as a whole. IS 1642-Materials and Construction has

provided Specification of materials, structural components, and construction type based on

the Fire Resistance Grading ranging from Type 1 (6 hrs) to Type 5(½ hrs). The Indian Codes

further specified the requirements for consideration of fire hazard form exposure to fire,

personal hazard, specific structures related as Chimneys, flues, hearths etc., electrical

installation. Non-electrical installations, fire fighting equipment, and Fire proof doors.

The International Fire Code (IFC) published by International Code Council is much more

intensive and covers wide range of aspects which are not included in Indian Fire Code and

NNBC. The structural outline of the IFC is listed in Table 1 in Appendix -11. The major

specific features not covered by IS and NNBC are a) Administration, b) Emergency Planning

and Preparedness, c) Fire Service Features, d) Building Service Features, e) Emergency

access gates, f) Tents, Canopy, membrane structures, g) Fire Safety during Construction and

Demolition, h) Provision of Water Supply for Fire Fighting, i) Fire Evacuation Planning, and

j) Identity of No-parking Fire Lane.

The design of important buildings, especially for high rise and special buildings has become a

complex process that requires integrating many skills, products and techniques into its

system. An intelligent building design is required to cater to various potential emergency

situations. NNBC 107 requires to be updated to the level of international code and needs to

address the pragmatic conditions existing in the downtown area and new built up areas.

A comprehensive comparison of various Fire Safety Codes is carried out and presented in

Appendix-11. A brief review of plans and programs including Building Bylaws applied by

KVTDC is also provided including the requirement of structural fire engineering,

requirement of high rise buildings, Qualification of Fire Protection Services, model outline of

Fire Protection Act.

5.4 Review of NNBC: 110, 111, 112, 113, 114 (Masonry, PCC, Materials,

Construction Safety)

5.4.1 NNBC 110: Plain and Reinforced Concrete

The code is represented as NEPAL AMENDMENTS TO IS 456 – 1978 and specifies

amendment of few terminologies as ― India‖ to ―Nepal‖ , ―Standard‖ to ―Code‖, etc.. Since

the use of this code again requires intensive reference to IS 456, the essence of this code is

lost and is practically not used.

Most of the references in IS 456-1978 to Indian Codes had been left unaltered and it was

stated that any subsequent revisions to IS 456-1978 will not be applicable to NNBC 110-94

until specifically recognised and updated.

Most important aspect of the code is that it has provided guidance for load combination

where Dead Load is treated with a loading factor of 50%. This factor needs to be harmonized

with NNBC 000 and NNBC 105.

The Table 12 provided the values of partial safety factors of various combinations of loads.

One more combination DL + 0.9 WL is suggested to be added.

When considering earthquake effects, the load combination requires WL to be replaced with

EL.

The code may include following points when updating:

Limit State Method

Provision of Two way slab design requirements

Provision for cantilever slab (eg slab with 3 side support)

Various types of slabs with necessary coefficients αx, αy, βx, βy and provide a table of

variables.

Design example of reinforced concrete structure, detailing of reinforced steel should be

shown in NNBC to meet Earthquake Codes

Provisions of Pre-stressed Concrete should be included

Provisions for Precast Structures should be made.

5.4.2 NNBC-111: 1994: Steel

The code comprises Indian Code IS 800-1984 Code of practice for General Construction in

Steel (Second Revision) with amendments to ensure compatibility with NNBC 000 and NNBC

105 - Seismic Design of Buildings in Nepal. It states that References to Indian material codes

will remain unaltered until such time as appropriate Nepal Standards or codes are developed.

Extensive use of the New Zealand Standards NZS 3404: 1977 Code for Design of Steel

Structures has been made. The code is specified as NEPAL AMENDMENTS TO IS 800 –

1984.

The Code applies to general construction in steel and structures such as bridges, cranes, tanks,

transmission towers and masts are not considered. Similarly, materials less than 3 mm thick

and cold-formed light gauge sections are not considered.

The Code has made provisions for Seismic Design that include parameters as Ductile Moment-

Resisting Frames and Ductile Braced Framed.

Some specific comments to the clauses of the code are provided in Appendix-6.

5.4.3 NNBC-112: Timber 1994

This Code covers the general principle of design of structural timber and includes

specifications, classification of timber species and nail joint in timber construction.

The code is based on Indian Standard IS: 883-1970: Structural Timber in Building” (Third

revision) and IS: 2366-1983: Nail-Jointed Timber Construction (First Revision).

The Code does not cover anti-termite timber, plywood, and timber pile foundation.

The Code could be considered as more comprehensive since it contains data and information

on general characteristics of timber species as durability, basic stress, Moisture Content, sizes

of Sawn Timber, Data for Nailed Joints, bolted joints, and Glue Laminated Timber.

.

The Code has made Design Considerations which include additional requirement of capacity

for sustaining the worst combination of all loadings apart from the requirement of IS Code.

Some specific comments on the clauses of the code are provided in Appendix-6.

5.4.4 NNBC-113: Aluminum 1994

The document referred to as a series of guidelines intended only for design of simple

aluminum structures. Currently use of Aluminum as a structural material in Nepal is very

limited and a Code has not been prepared. For actual design, the Codes from other countries

should be referred.

The Guidelines include structural properties as Strength, Modulus of Elasticity, Creep,

Thermal Expansion and Contraction, Fatigue, Corrosion Protection, Fabrication, Welding,

Mechanical Jointing, and Heating.

In general it is assumed that the Code requires updating with indication of various properties

of aluminum with appropriate formula to allow proper design of aluminum structure. The use

of Aluminum in structures other than Buildings such as aircraft engineering and lightweight

thin shell structures related to Aero dynamical aspects for design consideration should also be

included. Supplementary examples of design and drawings will be very useful.

Some specific comments on the clauses of the code are provided in Appendix-6.

5.4.5 NNBC 114:1994 CONSTRUCTION SAFETY

The purpose of this standard is to provide reasonable degree of safety to construction related

personnel in building and civil construction works. The provisions in this code are the

minimum requirements that are to be adopted during building and other civil construction or

demolition work.

The Code has made provisions for the health and safety of workers in building construction

and demolition work, fire protection, equipment operation, material handling, traffic

management within the construction site, and any use of special materials such as chemicals

and blasting materials.

The Code has made specific provisions for Material Handling, First Aid Facility and Health,

Fire Fighting, Site Preparation Earthworks in Excavation, Construction of Foundations,

Construction of Walls, Construction of Roofs, Electrical Works, Temporary Works,

Demolition of Structures, Use of Explosives, and Labour Welfare. Apart from these factors,

there are many items which require Safety Consideration and shall be included in the Codes or

guidelines.

Various international entities directly engaged in the construction have issued Construction

Safety Manuals as part of their corporate responsibility and is governed by statutory laws, by-

laws and Contract Documents and enforced by the appropriate authorities. Some of the

important aspects covered by those Manuals are guiding principles and core functions of the

Integrated Safety Management System (ISMS).

The manuals provide general information on the requirements and procedures for prevention

of accidents, safety, loss of control in the construction, operation and maintenance, and

services. The safety objective is to foster a safety environment so that accident free

construction is achieved. The Contractors are charged with the responsibility for conducting

safe operations providing protection to all employees, the public, the client‘s personnel, and all

others who may come in contact with the project. Safety should be a part of the project. The

Manuals contain a) Definition, b) Construction Safety Program, c) Safety Requirements, d)

Equipment and vehicle operation, and e)Reporting Procedures.

5.5 Review of NNBC: 201, 202, 203, 204, 205 (MRT, Low Strength and

Earthen Buildings)

5.5.1 General

The main objective of MRT is to provide ready-to-use dimensions and details for various

structural and non-structural elements for up to three-storey reinforced concrete (RC),

framed, ordinary residential buildings commonly being built by owner-builders in Nepal that

include a) RCC framed with using brick infill walls, b) load bearing brick masonry, c) low

strength rural construction and earthen buildings.

The Design guidelines presented in the MRT are for ordinary residential buildings with the

seismic coefficient of 0.128 (equivalent to seismic Zone C (Terai and North of Himalayas).

However, the MRT design is applied in other high seismic zones without any further

improvement and beyond the limitations described in the code. The Licensed designers use

these guidelines and designs provided in MRT for any shape, size and height of floors and

building. The detailed designs provided are not founded by analysis and not compatible with

other codes (Fire Code, Plumbing Code, Electrical Code, Construction methodology, etc.)

resulting in smaller size of columns and beams.

The details in MRT designs are provided without consideration of construction requirements

for quality assurance (limitation of concrete placing from less than 1 m, allowing

consolidation of concrete, preventing honey comb in concrete and smaller dia reinforcement

(10mm and 12 mm in foundation and columns).

This has posed increased safety hazard. However, detailed account of these statements are not

determined since no detailed data are available and recorded. These designs are in general

had not been subject to any check for compliance with other codes as Fire Safety Code,

Construction Code, Construction Safety Code, Architectural Code, Planning Code, and so on.

The recent fire hazards in Nepal are associated with the buildings belonging to MRT category

and pose a huge risk.

It is assumed that the MRT is a kind of design examples prepared for ready to use, based on

over design and hence should not be a part of NNBC. Further, it is assumed that a set of

design examples should be prepared for ready-to-use purpose that would fulfill the

requirement of all applicable codes.

The recommendations set forth in this code should be mandatory for all types of LSM to be

built throughout Nepal without limitation to public buildings irrespective of where they are

to be built in Municipal and urban areas or in rural areas.

It will be interesting to collect the data and information on the building construction in recent

years and understand how far the MRT has been meaningfully utilized.

5.5.2 NNBC 201: Mandatory Rules Of Thumb - Reinforced Concrete Buildings with

Masonry Infill

The practice of using such walls is predominant, but they are treated as non-structural (and

hence not accounted for) in the design of the frames and pose a lot of safety hazard when

placed in ad hoc basis. Hence, the objective of this MRT is to ensure the proper placement of

such walls in order to derive positive effects and to achieve economy.

The MRT is intended for buildings of regular column-beam type with reinforced concrete

slabs for floors and the roof. The MRT presents ready-to-use designs for all structural

components, including detailing of structural as well as non-structural members, for infill

framed buildings.

5.5.3 NNBC 202: MRT-LOAD BEARING MASONRY

The MRT covers load-bearing masonry buildings meeting prescribed criteria. They do not

cover wooden buildings, mud buildings (low-strength buildings), or those constructed in

adobe.

This MRT is valid (with certain limitations as to span, floor height, etc.) for: i) load-bearing

brick masonry buildings constructed in cement mortars up to three-storeys, ii) load-bearing

stone masonry buildings constructed in cement mortar up to two-storeys, and iii) load-bearing

brick masonry buildings constructed in mud mortar up to two-storeys.

The MRT for Load Bearing Masonry is assumed to contain several weaknesses that has

influence on structural requirements. Some of the examples are as follows:

MRT is intended to cater primarily to the requirements of mid-level technicians (overseers

and draughtspersons) and hence reference to other codes shall be eliminated since they don‘t

have access to these codes. MRT shall be made independent and all required details shall be

provided.

The recommended minimum wall thickness of 230 mm is practically not followed since the

sizes of the bricks used in such construction have large variations and practically falls

beyond the tolerance limits, and one side of masonry walls could not be constructed to

plumb line. Hence, these walls could not be considered in terms of compliance to structural

safety requirement.

The nomenclature used in this section as two storeys and three storeys are not correct. Since

the stair case part is not included which actually, in terms of structural configuration, adds

up to additional floor. So actually, two storeys Buildings are only one storey buildings and

so on.

In the Scope, it was mentioned that ―the MRT does not cover wooden buildings, mud

buildings (low-strength buildings), or those constructed in adobe. No attempt should be

made to apply these rules to these latter buildings‖, but the load bearing masonry in mud

mortar is included in the design examples. The definition of ―adobe‖ construction should be

provided and some consistency should be observed. The load bearing masonry in mud

mortar should be taken to NNBC 203.

The local size of bricks used in practice are not considered and the size of bricks used are

not consistent

The indication of engineering properties of materials and masonry or mortar as cube strength

in MRT has ―Less Sense‖ since MRT is made for non- engineered buildings without taking

care of quality assurance requirements, and dealt by inspectors and non-professional persons

at site. They do not warrantee the safety envisaged by the Code. .

No buildings categorized into ―Important Buildings‖ should be allowed to design based on

MRT since these buildings falls outside the limitations of MRT.

Masonry Bonds shall be described in full details.

The requirements of opening in walls are not checked properly by the Designers and the

authorities in Building Permit Section of Municipalities.

The Reinforcement provision around the opening is impractical.

A toothed joint shown in Fig 7.3 is wrong since the joint shall be made at corners at a

stepped configuration and not vertical.

The introduction of horizontal reinforcement at several locations within the height of walls

is the best part of the code.

The reinforcement Fe 550 for these small buildings of one or two storey buildings may not

be required in view of economy.


Low Strength Masonry

The MRT is prepared as the Guidelines for Earthquake Resistant Building Construction of

Low Strength Masonry (LSM). This is intended to be implemented by the owner/ builder with

some assistance from technicians.

There are some points that need to be considered in updating of the Code. They are:

The attic floor in general is not taken as structural element and not taken into account in

storey calculation. This is confusing and need to be elaborated.

The provision of vertical reinforcement disturbs the masonry bond and in general creates

weak zone

The vertical reinforcement requires corrosion resistant treatment

The need for provision of Diagonal Bracings is complicated and cannot be constructed

properly

Bonding design and illustration should be provided. Other bonding not mentioned in the

code shall be permitted.

The wall thickness of 300 mm (Clause 2.7) for stone and brick masonry is not consistent.

The mix component of cement concrete shall indicate the water cement ratio as fourth

component (1:2:4:0.5), 0.5 being the water cement ratio.

The use of Bamboo post at the centre of a wall is complicated and disturbs the masonry

structure and serves no purpose since it is not bonded with the masonry (Fig 6.1)

Use of vertical steel around the opening is very complicated and practically not used (Fig

10.1). The use of horizontal bands should be included.

The provision in the Code for Fire Retardant Treatment of Bamboo, Timber and Thatch is

the best part of the code.


Earthen Building (EB)

This guideline is prepared in order to raise the seismic safety of earthen buildings. This is

intended to be implemented by the owner/builder with some assistance from technicians.

Other comments referred above in NNBC 204-MRT are valid for this Code as well.

5.5.6 NNBC 205: 1994 - MRT Reinforced Concrete Buildings without Masonry Infill

The MRT is intended for buildings of the regular column-beam type with reinforced concrete

slabs for floors and the roof without any contribution of masonry infill walls in resisting the

vertical or seismic loads. The frames are designed to resist earthquake forces as a bare frame.

The MRT presents ready-to-use designs for all structural components, including detailing of

structural as well as non-structural members for the specified building type.

Some of the important aspects that need to be addressed are described herewith:

The Code requires reviewing since in practice there are no buildings without infill walls.

The design recommendations need to be reviewed in terms of possibility for maintaining

Quality assurance requirements as consolidation of concrete, prevention of fragmentation

of concrete ingredients, prevention of honey comb in concrete, maintenance of ratio

cement ratio in concrete,

The column size of 250 mm with orthogonal and diagonal stirrups and hooks do not

allow any space for consolidation of concrete mass,

The foundation pad with sloping top surfacing cannot be compacted

The use of 10 mm and 12 mm bar in foundation and columns are not acceptable in view

of possibility of corrosion of steel in due course of time

The provisions in this MRT for construction of infill wall are not different than that of

MRT with Infill Walls. The provision of Infill Walls in anyway does not make it

practically different from each other.

5.6 Review of NNBC 206: 2003 - Architectural Design Requirements

5.6.1 General

The Building by-laws for Greater Kathmandu Valley, prepared by Kathmandu Valley Town

Development Committee and NNBC 206: 2003 Architectural Design Requirements are the

basis for the recommendation to update the Architectural Design Code.

The updated version of the existing code NNBC 206: 2003 Architectural Design

Requirements will serve the purpose of guiding the building designers and planners to fulfill

their responsibilities of creating built environment that will be safe, healthy and beneficial to

the community as a whole.

The code will not contradict the innovativeness and creativeness of the designer and the

planner. This will be the logical conclusion of the contents of the code, as it spells out the

minimum requirements in the design of buildings and the surrounding in serving the

objective of the code.

After much deliberation at different stages, the consultant did not receive any essential

criticism or recommendation for change in the present documents, exclusion of neighborhood

planning related articles and conservative approach in FAR values were, however, spelled

out.

As the elements of Zoning Regulation will not form the part of this code, the

recommendations for updating of the code based on the above and certain new elements are

provided in more details in Appendix-9 to be considered while updating the existing NNBC

206: 2003 Architectural Design Requirements.

A building by itself cannot guarantee fulfillment the objective of a code. The building stands

in a space of multiple of such objects. Therefore, certain aspects of neighborhood planning

needs to be included which are absent in the existing NNBC 206: 2003 Architectural Design

Requirements.

Similarly, the code has implicitly relied heavily on Building by-laws. It should have been the

other way round. The updated code is suggested to be the guide in preparing the by-laws. The

other aspect to be mentioned is the non-consideration of high rise buildings, which has to be

taken into account in the new code.

5.6.2 High Rise Buildings

The above item wise recommendations will be applied to high rise buildings separately

including the separating distance between high rise structures.

The aspects of i) Light, ii) ventilation and iii) emergency exit (smokeless stairs) will be

specified for high rise buildings separately. The rest will be treated in the general design

requirement part of the code.

5.6.3 Other aspects

Ample sketches and drawings will be included interpreting the articles wherever applicable.

Definition of different parts of building which will be mentioned in the code needs to be

clearly given in the new code.

5.7 Review of NNBC 207: 2003- Electrical Code

The code generally referred to the Nepal Electricity Authority and makes the fundamental on

Electricity Act 2049 and Electricity Regulations 2050 and general requirement of Electricity

Supply Authority which is very authentic. But again reference to Indian Codes makes it

redundant and the use of NNBC becomes limited.

The Code while had made trial to recommend the certain aspects of planning, it does not

include the basic design aspects as Type of occupancy, type of supply required (voltage,

phases and frequency level), Load Demand, atmospheric condition, degree of protection

(Earthing, insulation), future increase of load, energy consumption and conservation

requirement, continuity of supply, need for suppression of radio and telecommunication

interference; maintenance and safety aspects and comparison of costs of various alternative

variants.

There are several important aspects which required to be addressed in the code. Appendix-10

have provided certain description of short comings and provided facts and figures which may

be helpful for future code development.

5.8 Review of NNBC 208: 1994 - Plumbing and Sanitation

The code in general covers following main topics and deals with the internal requirements

within a building or premise:

Water Supply

Waste Water Disposal

Rain Water Disposal

5.8.1 Water Supply

The water supply section has generally covered: a) Water Supply Requirements for

Buildings, b) Water Storage (General Water Storage Tanks, Underground Storage, Overhead

Storage, c) Distribution System and Pipe Work, d) Fire Fighting Provision (Hydrant System).

The code does not make provision for change of water demand based on the geographic

region and sub-climatic conditions, occupation, type of institution, and conditions of city

supply, sources of supply. The code also does not cover other important aspects as alternative

sources of water supply, water reuse, water recycling and water conservation which is

common in the place of water scarcity.

The need for a systematic approach towards development of code is very essential and it

provides guideline for proper development of the code. In absence of the proper outline

structure, the code has lost basic important aspects as water quality, water pollution control,

control of leakage, safety (access to water storage by children, electrical safety, equipments

and pumping systems). Several fatal accidents observed in relation to water pumping cannot

be ignored.

5.8.2 Waste Water Disposal

The Section of NNBC comprises of scope describing various types of collection system

(Single pipe, two pipes), methods of prevention of vermin and foul smells entering the

building. This code does not work, since there not a single building in Nepal which prevent

foul smell of toilet and all rivers are polluted with waste water and has created huge

environmental damage. There is need for thorough review of this code.

The code mentions about adequate sizing and slopes and other parameters required for proper

design of waste water system, but no particular data provided which is required to be

complied with. A proper table of minimum design parameters would be useful.

The need for ventilation of pipe system and extending the vent pipes to roof levels is

indicated but the need for ventilation of indoor space is not mentioned.

The demand table for waste water appurtenance is well covered in various tables.

5.8.3 Rain Water Disposal

The Scope of Rain water disposal comprises of need for rain water collection from roofs and

balconies and disposal through a gutter system. Free fall of rain water from roofs is not

allowed for building above one storey. However, it shall be noted that this code is not used in

practice and is not effective.

The code mentions about the need for disposal of storm water system but does not precisely

discuss about the possibilities of connection to sewerage system or storm water drainage

system or open disposal to street drains and public spaces. This aspect needs to be dealt in

more precise manner.

The slope suggested for rain water drainage from various surfaces is considered inadequate

and needs reconsideration.

The restriction to connect the rain water pipe with a sewer is not practical since the sewage

system in most part of the cities is based on combined (Sewage and Rain Water or Storm

water) system. Either a categorization or zoning of storm water drainage shall be introduced.

In general, the following issues shall be taken into focus for updating of this code:

Rationalization of definitions, and inclusions of more terms and terminology.

Include first design parameters such as minimum flow through taps, residual head,

minimum slope, minimum cover etc

Include friction head loss diagram in form of nomograph, tables and appropriate

equation.

Make provisions related to domestic hot water supply installation

Make provisions related to water supply and sanitation in high altitude and sub-zero

temperature regions of the country,

Include inspection, testing maintenance requirement.

Include sizing of rain water pipes for roof drainage in more rational basis, and

techniques for rainwater harvesting,

Protection of joints between pipelines and structures for prevention of joint leakage of

rain water and other surface water

Protection of pipelines from potential damages (corrosion, mechanical damage,

chemical attack, fire)

Requirement of refuse chute, if any

A brief comparison of NNBC has been made with Water Treatment Hand Book: Degremont

– 1979. The findings and inferences, problems and issues derived during study are written

in commentary and suggestion form with articles related in the NNBC publication. All these

issues and problems are to be considered and shall be adopted in future in the revised code.

Appendix-11 has included various data and information that would be useful for updating

the code.

6 Conclusion

Code Structure, Nepal Standards and Family of Codes

There is a gross confusion about the hierarchy and priority of documents in relation to Act,

Bylaws, Codes (NNBC), Standards (NS), and Directives (PWD), Specifications, Manuals

Instructions and administrative circulars. This aspect needs to be clarified and clear

demarcation and definition is required.

Institutional Arrangements for Implementation of NNBC

There is no single institution responsible for all earthquake related matters in Nepal.

DUDBC has taken initiatives in drafting the NNBC, drafting Building Act and

Regulations. But there are various institutions and agencies that are responsible for various

earthquake related matters, and the coordination among them is practically not provided.

For this reason, the issues related to NNBC remain unattended and keeps waiting for a

particular project to start.

MRT not to be a part of NNBC

Strong voices were noted for treating MRT as non-Code document since it is just an

example of design of various types of buildings and details following the provisions of

NNBC. This document is incomplete and do not include the requirements of other codes as

Fire Code, Plumbing Code, Environmental Code etc. The quality assurance and

construction complexities are not considered. Lalitpur Municipality from the very day of

application of NNBC adopted certain changes in MRT. This document should be

developed as model examples that fulfill the requirement of all codes and should be served

as guide for proper design and shall not be a part of the Building Code.

Lessons Learned from Municipality Experience

Lalitpur and Kathmandu Municipalities have had accumulated very important experience

of implementation of Building Codes along with the grant of Building Permit process and

inspection of Building Construction. But in absence of comprehensive reports on Building

Permit process and Building inspection, no meaningful lessons could be derived.

The information and data from other municipalities, DDC and VDC are rarely available.

Reforms in Building Act and Building Bylaws

Current practice has indicated that in Nepal where construction inspection falls within the

jurisdiction of local authority, the only way to successful implementation is to introduce

code compliance requirement in the Building Bylaws adopted by Municipalities, and

subsequently by DDC and VDC.

The Building Act requires to be amended to include the mandate of DDC and VDC to

comply with the requirements of NNBC (including whole family of codes).

Application of Bylaws in VDC

Most of the areas in country side and rural areas are not covered by Building Act and

Building Bylaws making the rural areas more vulnerable for construction safety and

remain vulnerable to the earthquake hazard. This loop hole in Building Act has prompted

many builders and owners to shift to VDC areas for construction for avoiding the need for

obtaining Building Permits and avoiding application of NNBC. This provision has

defeated the purpose of NNBC in general.

Effect of neighborhood safety and Architectural Design Requirement

The important aspects of urban development as conservation of historic buildings,

aesthetics and context of urban area development affecting the neighborhood safety are

missing which has a huge toll on the urban safety. The building permit process does not

consider the effect of neighborhood safety including historic buildings and World Heritage

Sites or Preservation areas. Similarly, the relationship between Architectural Design

Requirement, neighborhood planning and zoning requirements had not been co-related with

each other. This weakness is inherited in the haphazard urban development.

Change of occupancy

There are several occasions of change of occupancy category of the buildings that threaten

the safety of life and property. Recently, several of hotel buildings have changed

occupancy to supermarkets and office buildings. The residential buildings are easily used

for accommodating schools, warehouses, and offices. The safety of Such Buildings is in

question. The municipalities and Government authorities are not in position to monitor and

verify the safety of such buildings.

High Rise Buildings

The requirement of high rise buildings in terms of overall safety is different than that of

low rise buildings. The quality of materials and reliability of technology is much stringent

and operation and maintenance of the service require higher degree for reliability. The

requirements for high rise buildings are not included in Building Bylaws and Building

Codes.

Abolishing MRT

MRT is widely used document and if properly developed could be a good instrument to

enhance the earthquake safety of the municipalities and rural areas. But, since MRT as

such is not complete, does not comply with requirement of various other codes and grossly

misused by the licensed designers of municipalities, it should be considered for abolishing

and replaced with good example of standarised design of typical building.

7 Recommendation

Drafting of NNBC – a commendable job

The drafting of NNBC and adoption by the government was a marvelous milestone in the

history of Engineering and Nation Building. The Department of Urban Development and

Building Construction, UNDP and UNCHR deserve high commendation including those

institutions and organizations involved in preparation of the Codes (NNBC) and Standards

(NS).

Delays in Implementation of NNBC

The Codes (NNBC) was much delayed in implementation but it got its pace with the

initiatives of Lalitpur Sub-Metroplotan City for implementation of NNBC in their Building

Permit Process in Jan 2003 and followed by Kathmandu Metropolitan City since Jan 2005.

The implementation of NNBC, and particularly the Earthquake Safety issues, is still very

difficult since this aspect is still not institutionalized and no specific institution has been

created who will be dedicated for Code Development and Implementation. No particular

instrument has been identified for implementation of the Code.

Need for Nepal Code Council

There is a dire need for establishing Nepal Code Council that will address the development

issues of Codes and their implementation. The Council needs to take care of the

implementation and legal issues, providing encouragement to the stakeholders, record

occurrence of events, providing training to the professionals and designers, and building

awareness of the stakeholders, regularly updating the Building Codes, conducting

consultation meetings and conferences. The Council also would be interested to develop

partnership with private and public sectors to develop various codes.

Family of Codes

NNBC is a collection of individual codes which are not complete in itself. For this reason,

the effect of implementation of NNBC was not felt effective. This is evident from the

quality of construction in the society. May be it would be more effective when compiled

into a unified code that takes into account the family of various other codes as Urban

Planning Code, Fire code, Disability Accessibility Code, Environmental Code, Plumbing

Code, Electrical Code, Construction Code, Construction Safety Code etc including

provision for adoption of administrative procedures for implementation.

Reference Codes

Most of the codes are developed by the institutions that are involved in primary research or

manufacturing products or services. Many of professional associations are the originators

of the Codes. It is fundamental that these institutions and entities are included as reference

codes and allowed to refer as National Building Codes with full responsibility vested on

the Designers and the owners.

Examples of Model Designs

In order to enhance the application of the Building Code in a proper manner and making it

more popular, it would be imperative to prepare certain examples of Model Designs that

could be followed by young generation and professionals and replicate the algorithm of

compliance of Building Code requirements.

Outsourcing Municipality Responsibility

It is obvious that the municipality authorities have limited capacity to check and monitor

the compliance with Family of Building Codes. For this reason, the Building By-laws and

Municipality Regulations should make provisions for outsourcing the municipality

responsibility for monitoring the design and construction inspection activities and

involving panel of experts as and when required.

Audit of Procedures of Implementation of NNBC by Municipalities

The Implementation of Building Codes by Municipalities is limited within the municipality

and no lessons are derived that would helps to improve the implementation procedures of

the Codes and help to update them. For this reason, it would be essential to audit the

Building Permit Process including implementation of Building Codes.

Mandatory Application of Bylaws through out the country

The need for enhancing the earthquake safety is fundamental. This calls for coordinating

the simultaneous application of Building Bylaws and Building Code together

comprehensively providing warrantee for compliance of Building Codes through out the

country without limitation. This would require amendment to the Building Act and

Bylaws.

Various Other Issues

There are several issues that required to be addressed. They are related to skill and

capability of Human Resource as trained professionals, skilled labor and monitoring

authorities, method of handling of construction materials, quality of materials and

equipment, specification of materials and workmanship, method of information

dissemination including acceptable manner of advertisement, education and licensing,

intellectual ownership of designs and many other aspects described above in various

chapters.

Priority of Updating NNBC

The priority of updating the Nepal National Building Codes could be listed as follows:

Priority 1- Abolishing MRT as a part of Building Code and substituting with Good

Examples of Standardized Design of Typical Building that are popularly

constructed in urban and rural areas. If some one adopts the typical design

without change, the process of Building Permit Grant could be simplify and

limit to the verification of ownership and provision of Building bylaws.

Priority 2- Identification of the gaps in the Code Structure including priority of Building

Act, Building Byelaws, Standards, Specification, Manuals, Directives,

Instructions,

Priority 3- Adopt the International Building Code with suitable amendments wherever

required. (Part 1: General and Part-2: Specific Changes pertinent to the

Country)

Priority 4- Introduce new codes that are not covered by IBC and codes specific to the

country and locality including Family of Codes described in Chapter 3.5

above.

Priority 5- Prepare Commentaries, guidelines, directives, Illustrations (MRT) and

Training Manuals shall be developed in order to enhance the effectiveness of

the updated Codes.

The End

Appendix-1: List of NNBC

Appendix-2: Check list of activities for the study

Appendix-3: Interaction with Target Groups and National Workshop

Appendix-4: Review of NNBC: 000, 105 (State of Art, Seismic Design)

Appendix-5: Review of NNBC 101, 102, 103, 104, 106, 108, 109 (Loads,

Occupancy, Site Consideration)

Appendix-6: Review of NNBC: 110, 111, 112, 113, 114, (Materials)

Appendix-7: Review of NNBC: 107 (Fire Code)

Appendix-8: Review of NNBC: 201, 202, 203, 204 and 205 (MRT)

Appendix-9: Review of NNBC: 206 (Architectural Code)

Appendix-10: Review of NNBC: 207 (Electrical Code)

Appendix-11: Review of NNBC: 208 (Water Supply and Sanitation)

Reference Materials

NNBC 000: 1994 to NNBC 205:1994, Nepal National Building Code Requirements, HMG of

Nepal, Ministry of Physical Planning and Works, DUDBC, Kathmandu, Nepal, 2050.

NNBC 206: 203 to NNBC 208:2003, Nepal National Building Code Requirements, GON of


IBC 2006 International Building Code, International Code Council, USA.

IS 13920: 1993 Indian Standard Code of Practice for Ductile Detailing of Reinforced Concrete

Structures subjected to Seismic Forces, Bureau of Indian Standards, New Delhi, India.

IS 1893 : (Part 1) 2002 Indian Standard Criteria for Earthquake Resistant Design of Structures

Part 1 General Provisions and Buildings (Fifth Revision), Bureau of Indian Standards, New

Delhi, India.

IS 1893: 1984 Indian Standard Criteria for Earthquake Resistant Design of Structures, Bureau

of Indian Standards, New Delhi, India.

IS 4326: 1993 Indian Standard Code of Practice for Earthquake Resistant Design and

Construction of Buildings, Bureau of Indian Standards, New Delhi, India.

IS 456: 1978 Indian Standard Code of Practice for Plain and Reinforced Concrete, Indian

Standards Institution, New Delhi, India.

IS 800: 1984 Indian Standard Code of Practice for General Construction in Steel, Bureau of

Indian Standards, New Delhi, India.

NEHRP 2003 Recommended Provisions for the Development of Seismic Regulations for New

Buildings, Building Seismic Safety Council, Federal Emergency Management Agency, USA.

ACI 530-02/ASCE 5-02/TMS 402-02, (2002), Building Code Requirements for Masonry

Structures, Masonry Standards Joint Committee, USA.

ACI 530-99/ASCE 5-99/TMS 402-99, (1999), Building Code Requirements forMasonry

Structures, Masonry Standards Joint Committee, USA.

BS 5628: Part 1, (1978), Code of practice for structural use of masonry, Part 1 Unreinforced

masonry, British Standards Institution

Eurocode 6, (1996), Design of Masonry Structures – Part 1-1: General rules for buildings –

Rules for Reinforced and Unreinforced Masonry, European Committee for Standardization,

Brussels.

Review of Design Codes for Masonry Buildings IITK-GSDMA-EQ10-V1.0 15

IS:1905-1987, (1987), Indian Standard Code of Practice for Structural Use of Unreinforced

Masonry, Bureau of Indian Standards, New Delhi.

NZS 4230 Parts 1 & 2: 1990, (1990), Code of Practice for the Design of Concrete Masonry

Structures and Commentary, Standards Association of New Zealand, Wellington, New

Zealand.

National Building Code of Canada

IS:875(Part 4)- Snow load

SP 20(S & T): 1991, (1991), Handbook on Masonry Design and Construction, Bureau of

Indian Standards, New Delhi.

NNBC 109:1994, Nepal National Building Code, Masonry: Unreinforced

BS 5628: Part 1, (1978), Code of practice for structural use of masonry, Part 1 Unreinforced

masonry, British Standards Institution

Eurocode 6, (1996), Design of Masonry Structures – Part 1-1: General rules for buildings –

Rules for Reinforced and Unreinforced Masonry, Europea Committee for Standardization,

Brussels.

Review of Design Codes for Masonry Buildings IITK-GSDMA-EQ10-V1.0 15

Engineering, New Zealand, Paper No. 1790.

Recently Modified Articles –Law and Database of ROC.

Schneider Electric – Electrical Installation Guide-2009.

National rules for Electrical Installations, Third Edition, Amendment No.1, Electro-Technical

Council of Ireland Ltd,2001.

National Electrical Code 2005, -Building code for the Village of Tinley Park, Cook ..

North Dakota State Electrical Board, Laws, Rules and Wiring Standards of North Dakota.

Distribution Code-Regulatory Framework of the Pakistan Distribution Electric Supply System.

Nepal Electricity Regulation 2050 (1993), H.M.G., Nepal

Nepal Electricity Act, 2049 Royal Seal: 17 December,1992 (2049/9/2)

National Building Code Part VIII Building Service Section 2 Electrical Installation, Bureau of

Indian Standard.

Fire protection and prevention act, 1997

Review of Fire Codes and Byelaws By G.B.Menon, Fire Adviser, Govt. of India {Retd.}

Cochin Ex-Chairman CED-22 Fire Fighting Sectional Committee Bureau of Indian Standards.

And J.N.Vakil, Asst.General Manager{Retd}, TAC/GIC, Ahmedabad Ex-Chairman CED-36

Fire Safety Sectional Committee Bureau of Indian Standards.

DEV KUMAR SUNUWAR , City fuel stations vulnerable to fire hazard

List of NNBC

Appendix-1: Nepal National Building Code Nepal Standard

Vol Code Title Page Standards Page

1 NNBC

000:1994

Requirements for State-of-the-art Design 1-10 NS 504 1-19

2 NNBC

101:1994

Materials Specifications 1-37 NS 505 1-39

3 NNBC

102:1994

Unit Weight of Materials 1-1 NS 506 1-52

4 NNBC

103:1994

Occupancy Load 1-1 NS 507 1-25

5 NNBC

104:1994

Wind Load 1-4 NS 508 1-30

6 NNBC

105:1994

Seismic Design of Buildings in Nepal 1-26 NS 514 –Earthquake

Resistant

1-

7 NNBC

106:1994

Snow Load 1-4

8 NNBC

107:1994

Fire Safety 1-4 NS 509 1-6

9 NNBC

108:1994

Site Consideration 1-12 NS 510 1-10

10 NNBC

109:1994

Masonry: Unreinforced 1-37 NS 512 1-38

11 NNBC

110:1994

Plain and Reinforced Concrete 1-4 NS 511 1-139

12 NNBC

111:1994

Steel 1-8

13 NNBC

112:1994

Timber 1-18

14 NNBC

113:1994

Aluminum 1-4

15 NNBC

114:1994

Construction Safety 1-9

16 NNBC

201:1994

Mandatory Rules of Thumb Reinforced

Concrete Buildings with Masonry Infill

1-40 NS 1-48

17 NNBC

202:1994

Mandatory Rules of Thumb Load Bearing

Masonry

1-49 NS 517 1-51

18 NNBC

203:1994

Guidelines for Earthquake Resistant Building

Construction: Low Strength Masonry

1-54 NS 514 1-69

19 NNBC

204:1994

Guidelines for Earthquake Resistant Building

Construction: Earthen Building (EB)

1-42 NS 515 1-60

20 NNBC

205:1994

Mandatory Rules of Thumb Reinforced

Concrete Buildings without Masonry Infill

1-29 NS 1-36

21 NNBC

206:2003

Architectural Design Requirements 1-9

22 NNBC

207:2003

Electrical Design Requirements For (Public

Buildings)

1-18

23 NNBC

208:2003

Sanitary And Plumbing Design Requirements 1-39

Appendix-2: Check list of activities for the study

Collect Building Codes (NNBC, FEMA, IBC, AIJ, Eurocode, Chinese Code, New Zealand

Code PWD)

Collect WHO Standard doe Sanitation Water Supply and Waste water Disposal


implementation for government buildings by DUDBC


implementation in municipalities;

Study of relevant codes by each team members and making notes

Summarise notes on study of codes

Categories the problems and issues

identify target group for interaction

invitation for participation in interaction program

Interaction with the users of the Codes as licensed designers of municipalities, professional

consultants involved in the Earthquake engineering, municipal and government authorities,

professional organizations;

prepare questionnaires, check list for interaction and discussion materials

identify venue and time of following interaction sequences:

Initial Introductory Interaction

Interim Interaction

Draft report presentation

Prepare proposals for change in each NNBC codes

Review Building Permit process KMC, LSMC

Categorisation of Buildings – High, Medium and Low rise buildings

Preparation of Recommendation for update of NNBC with detail information on

amendments, revisions, alterations to be made.

Formulate Code Structure

Appendix-3: Interaction with Target Groups and National Workshop

Group 1: ERRRP/UNDP

Group 2: DUDBC, SCAEF, NEA, SEANEP, NSET, SEEN, SOPHEN, SOMEN, FCAN, FNCCI,

Group 3: LSMC and Licensed Designers

Group 4: KMC and Licensed Designers

Group 5: National Workshop

Notes on the Interaction

Dec 28, 2008: Interaction with ERRRP/DUDBC (Group 1)

The Initial Interaction with the National Program Coordinator Er Amrit Man Tuladhar and Er

Niyam Maharjan, ERRRP covered following points:

Attention is drawn on NNBC 205:MRT which is

widely used by the municipality designers and

rural construction

The Safety factors, Importance factors, Response

spectra recommended in NNBC have been a

concern for many professionals and experts who

have considered the factors as inadequate

compared to the outcome of other codes

Several designers and specially Lalitpur Sub-

Metropolitan City has recommended for changing

the NNBC recommended minimum size of

column of 9‖x9‖ to 9‖x12‖, and changing the

concrete grade from M15 to M20 or higher.

Feb. 5, 2009: Interaction with Institutional Stakeholders (Group 2)

Introduction

Formal Consultation with Stakeholders for sharing experience of implementation of NBC

Briefing on Update Needs on NNBC

Inception Report on Dec. 31 – No Comments

Criticism on NBC

Adequacy of Code Provision/ Guidelines/ Manual/ Specification – Construction Practice

Objectives of Updating of NBC

User friendly

Safety Assurances

Confidence

What updating required in NBC

Code structure – Hierarchy of Provisions

Additional Codes – International Codes have 16 various codes included

Reasons for Using NBC

Confidence: IRC, IS

Demand for NBC is not felt

Maintaining safety, Image, - make complete code

Accepted Codes (IS, BS, ASTM)

Format of Code

Individual code

Compiled code/ unified code

standards & building codes relation

Adaptation of other codes/ IS code and other

use of materials not mentioned in NBC

Professional and Administrative consistency of NBC and standards

Implementation of Codes

Interaction with NBSM – standards making procedure – updating needs

DUDBC is member of NBSM

Regulation for implementation, and practicing is in mess

Design is considered, but construction practices not mentioned

Controlling Quality

Applicability of materials: TMT Fe 500 or TOR Fe 415 specification of parameters – strength

characteristics – elongation/ strength

Prefab materials

Construction is mess: quality regulation not in place

monitoring value is getting less/ haphazard construction

Urgent matters

Product dominant market/ Ad base market

Monitoring of Ad

Mechanism for addressing Technical issues is lacking

Intellectual property (limited)

Mechanism to invite participation of masons, stakeholders, owners,

info dissemination to mass

Supervision: maternal/ manpower monitoring is lacking

Safety of public during material handling

Electrical Safety

Role of inspectors – NEA supplies, operations

Electrical hazards: standards of appliances – efficiency, economy

Dumping site for CFL luminaries – proven factors

Miscellaneous matters

Application of Water Supply, Sanitation, Electrification, Fire codes:

More interactions required at institutional level

Planning, aesthetics, architecture issues are missing

Communication, gas supply, Cement supply, storage

Architects dictate shape of structure –

ductility of structure and building configuration;

Old structure occupancy – change in occupancy

Irregularity of shape in plan/ elevation/

Old & new structure – existing stock/ heritage/ monumental/ Economy/

Rules made for misbehavior to people

Market domination approach

Building bylaws

do not include several disciplines:

o health & hygiene;

o Supermarket, high rise building, basement –

o market forces dominate development: it has consequences

o Safety of neighborhood:

o Nachghar

o USAID

o Kathmandu District Court

o Abandoned houses,

o Hunting dangerous building

o Bridge/ specific structure/ water towers, electrical towers

o Hoarding board, FM tower, mobile tower,

o Building permit for certain time, renewal of building permit

Construction Safety

formwork,

Audit

Insulation –

Problem, complain by layman,

Capacity of personnel, qualification

Certification of designer, contractor, owner

Education

Use of Code in Education/ Code based education

Panel review,

Awareness – colleges are good venue

Include NBC education in colleges

Purbanchal University; ME in EE in Khwopa Engineering College

Awareness of students

NBC projects!

Comments on NNBC

NBC should include all aspects including innovative

MRT – Use by L, K & Dharan: 201, 202, 205 (1000 sq.ft. 3 floor)

Driving force for execution

NBC under Building Act; MRT should not be under NBC

Commentary on all clauses of NBC

Feb. 9, 2009; Interaction with Licensed Designers in LSMC (Group 3)

Application of NNBC in LSMC from 2003

o Effective implementation of NNBC as pilot case;

o A lot of technology has been developed and need for updating NNBC is felt;

o interaction with practitioners

o Sharing the experience;

o Initial exposure in use of NNBC; a lot of changes from 1994;

o Need for Revision of NNBC

Most of international codes are revised every 3 years based on technological achievements;

High rise buildings are new things – materials changed,

Building permit process

Upgrading drawbacks;

Historic/ monumental buildings, fire, sanitation, electrical safety, planning, environmental

codes are not included;

Design and construction differs (Residential Buildings, 2½ & 3½ storey designs)

Standarisation of designs and consideration: client‘s needs to be addressed

Instruction of Department of Archeology not considered

Lack of Proper Standard of details

Tie/ details: infill wall & frame Tie

Dachi Apa – Decorative layer – Safety Issues

Think over before tying of frame with infill wall

Tie only may not be enough; projection, parapet wall, sunshade may not be dangerous;

Prevention of structural collapse/ design consideration may be required

Lack of Awareness among contractors and labor

Designers + contractors: Joint design finalization

Licensing of contractors/ Owners to certify for safety

Investment shall be based on available resources:

Safety during construction

Safety of Glazed Façade, Granite facing and Anchorage, Architectural Code

Heating/ sound insulation/ indoor ventilation

Environmental hazard;

Lack of Design analysis

Soil bearing capacity – location selection, bearing capacity

MRT shall be abolished;

MRT is limited to 4.5 m. and 2 storeys, but applied for other buildings under coverage of MRT

Typical designs – to be provided;

NBC is not practically used

- Application is difficult in various municipalities

NBC to consider

- Worse case of load combination

- Load factors are low

- Lateral earth pressure in basement

- Load distribution for high rise and low rise

- Top flow load? Flip effect

- Time period < 0.1 N

- Load distribution of non-orthogonal plan

- Load reduction provision

- Concrete quality: base shear;

- Settlement, deformation, strength, crack opening

- Tall buildings, shear wall

- Static and dynamic analysis

- Retrofitting by laws / codes

- Repair and maintenance of old existing buildings/ code

- Disaster mitigation – building stock inventory

Electrical Safety

- Details for electrical wiring and safety of structure

Fire Safety to be Considered

- Fire in Ostankin tower of Moscow

Ownership of Design and Jurisdiction

- Mayer‘s bridge in Switzerland- Austria border: authors are designer, General contractor

and Formwork Contractor

- Whatever may be written, jurisdiction of designer is important

- Codes with community

NNBC has not considered the requirements of sector as

New high rise apartment buildings

Occupancy Change from Hotel Building to Super markets

Institutional Arrangement for Continuity of follow up for upgrading NNBC

Collection of Thesis works of Master‘s Degree from various institutes

Review Material Quality requirements

Quality management requirement of Construction

A number of Articles, comments and recommendation collected by ERRRP was also shared.

The list of materials received was included in References.

Feb. 27, 2009; Interaction with Licensed Designers in KMC (Group 4)

Venue: United World Trade Centre, Kathmandu

An interaction was held on Nepal National Building Code 2004 (amendments and update). The

conversation was chaired by Mr. Bimal Risal, Chief, Urban Development Department, KMC.

After a short welcome speech by the chairperson, the floor was opened for the technical

discussion. Following issues were raised and discussed.

Following the municipality building permit process for the design of buildings above six floors, it

is mandatory to submit the design parameters (whether conducted for seismic design or not)

following NNBC. The buildings with less than six floor, no design paprameters required to be

submitted.

Mr. Ram Chandra Kandel from NSET stressed that MRT is a part of the code and it is required to

provide more Technical details of building with various types details. Dr. PN Maskey clarified

that MRT should not be part of the code while it ccould be developed as guideline\ handbook for

non-engineered building construction.

As the present code lacks many technical aspects of design and implementation, the floor advised

to include as follows:

Planning code shall specify the Minimum size of stair case and safety.

Building for low income group

Code for Quality control and

Code of Ethics of Professionals, and Labor.

Apart from above technical discussing, Mr. Devendra Dongol, The Technical chief, KMC

highlighted the irrelevant building bye-laws which also require reviewing and updating. He

proposed that the code of building bye-laws should work in conjunction with each other and the

conflict should not exist between these two. However, the Consultant proposed that the Code

should be a part of bye-laws. And when bye-laws are to be made, no clause should supersede the

clauses of the code.

The content of the questionnaire for design parameter in Building permit process require revision

(specially, on the seismic assessment) in Kathmandu Municipality.

National Workshop, June 29, 2009 (2066-3-15) organised by ERRRP/DUDBC

The Workshop was organized by DUDBC with participation of DUDBC staff, UNDP

representatives, and representatives from SEANEP, EOI and others. Altogether there were 47

participants.Most important photo documentation is presented herewith.

The Comments and Suggestions obtained during the workshop and through the emails are

recorded as follows. The workshop also has had made audio record of the proceedings of the

Workshop. The comments are as follows:

1. Code should include a Mechanism for regular updating of the Codes.

2. The Report on Recommendation for updating of NBC includes codes as "Suitable/ Adequate"

which shall be more specific.

3. Building Code and Building Bylaws are two different documents and any confusion shall be

eliminated through additional studies.

4. Commentary Report NBC on is available. The revision of code shall consider the commentary

as well.

5. NBC 000 - The International State of Art should include the Own National State of Art

Building of the country.

6. Acceleration value in NBC 105 needs review

7. In the current context, promoting Performance Based Design will not be appropriate since it is

just introduced in Japan in 2003 for evaluate the structures. The knowledge in this field is not

enough and the construction technology should also be considered.

8. SP – Standard Practice, Standard publication, Design examples may be required

9. Provision for checking of Wind Load or Earthquake Load or both shall be made.

10. Limit state or working Stress method of design shall be included.

11. Design check during Construction stage shall be made.

12. EQ wave propagation destroys only certain buildings

13. In NBC 202, Analysis Model type shall be clearly elaborated.

14. In stead of referring to clear cover in IS 456, a separate Table shall be provided.

15. In IS 456, in the table for finding TC is determined based on % of Steel (pt) grade of concrete,

but TC refers to stress strain/ depth ratio.

16. NBC 111 refers to IS 800 but there is less practice of utilizing, the rivet joint type of joints

shall be analyzed in depth.

17. There are cases where TMT Rebar are cracked during Bending. This is the effect of Poisons

Ratio.

18. The Design Method prepared has suggested to use Super Element Method, but currently most

of the Tools have practice of using Finite Element Method. The effectiveness of SEM should

be more elaborated.

19. In the Architectural code NBC 206, the Plinth level and storey level houses shall be correlated

in neighborhood.

20. NBC 208 - Concealed plumbing and Electrical services may cause Structural Damages which

shall be considered in the code and provision shall be made to eliminate it.

21. Row housing shall consider the separation joints.

22. When considering Structural resonance, the Seismic coefficient method shall consider the

resonance factor.

23. The existing NBC is divided into four parties, but it may be made one document with various

chapters.

24. Building Act has made clear directives to implement NBC. In such case, it implies that

Bylaws also recognize NBC.

25. NBC Implementation

Implementation/ updating is a big challenge

The study will provide direction to resolve the challenges

The experts, govt. offices Building Act: Policy included

Effectiveness in whole community

Safety of large buildings should be the responsibility of designers

Small residents: owners are not aware of the Safety requirements of the Codes

Updating with new technology and Materials are required.

26. Construction safety is related with prevention of accidents at site and safety of the building

under construction. The safety issues are particularly related to

Electrical hazard

Gas hazard

Laser protection

27. EQ Safety Technology

Protecting old houses – retrofitting and making it cost effective

Chapter on Retrofitting should be included.

28. New context: introduction of disabled accessibility and making user friendly:

29. Building Act

The Building Act was formulated in 1994 and amended in 2006, and required that the

Building Permits are granted based on Building bylaws issued by Town Development

Committees; Designers are registered in Municipalities

The Building Bylaws do not specifically make recommendation on High rise buildings,

remains mainly the responsibility of the Designers to secure the Safety at all times.:

important

In the changed context, it is imperative to consider that the Building Codes should take

precedence to take over for ensuring the protection of life & property.

30. Report Formatting & structure

It is obvious that the report was prepared by a team of experts which is appreciable but it

would be appreciable if it could be improved in terms of language structure and formatting.

The Detailing of joints as granite façade shall be included.

31. MRT Issues

The issues raised in relation to MRT are OK but some of the points require rethinking

It would be wise to keep MRT within the Code since based on the experience of NNBC,

other countries as Pakistan, Iran, Bangladesh have started to replicate. This is a pride for

the country. Based on MRT the building stock of over 28,000 has been surveyed.

MRT would be appropriate to including as a part of Code. But the name could be changed

as required.

The case of Buildings with H/W < 3:1 is not mentioned. Why?

10% lump

NBC 205 shall consider analysis of infill wall.

32. NBC 107: Fire Code

Fire code should be reviewed in terms of National Perspective.

Effect of plaster and other elements that enhance the fire safety shall be considered.

IOE students had prepared M.Sc. thesis works in this topic.

IS 456 and NBC 110 may be referred

Fire resistance of Steel structures and chemical protection shall be included

Do not reduce structural strength

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1. General

Seismic design of buildings constitutes the principal component of the building codes. The

purpose is to reduce or mitigate the damage due to future earthquakes. It has been well

recognized that the single most important development in reducing earthquake losses in the

world has been the incorporation of seismic design provisions into the building codes. The

seismic codes of various countries are in a state of continuous evolution in research and

changes in construction practice.

The history of building code and hence the seismic design of buildings in Nepal is at

tender age compared to the same of other countries. The need for national building code in

Nepal was first strongly felt following the substantial loss and damage due to Udayapur

earthquake of 1988. The preparation of the building code was initiated in early nineties and

published officially only in 1994. The general response to the code has been lukewarm

since its inception, and is in a state of model building code rather than a national building

code in terms of legal status.

Substantial advance have been achieved in the knowledge related to seismic resistant

design of buildings and structures during the past 15 years since the publication of the

National Building Code of Nepal. Changes in seismic design provisions in seismic codes

of different countries from 1994 to the present date are many and far reaching in their

impact. Part of the reasons for such changes has been to incorporate the lessons learned

from the devastating large earthquakes. Inclusion of the lessons learnt from 1994

Northridge and the 1995 Kobe earthquakes have been the major highlights of 1997 edition

of Uniform Building Code with a considerable change in 1994 edition of UBC. Since then

the large earthquakes of Gujarat (2001 January), Sumatra-Andaman (2004 December),

Kashmir-Kohistan (2005 October) and China (2007) have resulted into devastating loss

and damage, imparting the new lessons to be incorporated in the next future seismic codes.

The lessons learnt from the past earthquakes, rapid development in the technology and

researches in the area of Earthquake Engineering have resulted into sophisticated seismic

codes in developed countries. The recent editions of National Earthquake Hazards

Reduction Program (NEHRP) Provisions following the custom of updating in a cycle of

three years substantiate the fact. The recommended provisions incorporated in ‗The

NEHRP Recommended Provisions for Seismic Regulations for New Buildings‘ have

increasingly been adopted in recent times by model codes and standards. If in United

States, there is a custom of revising the codes every three years, it may be not that easy in

case of developing countries like Nepal. The revised edition of the Indian standard Criteria

for earthquake resistant design of structures IS 1893(Part 1) 2002 came into light replacing

IS 1893: 1984 only after a period of 18 years. However, it should be recognized that the

updating of design documents like the codes is a dynamic process, and shall be

materialized as soon as possible to further reduce and mitigate the possible losses in future

earthquakes. In view of this, it is urgently needed that the present code on seismic design

of buildings in Nepal is carefully reviewed with an objective of removing any deficiencies,

errors or scope for misinterpretation. Moreover, development of commentaries or

explanatory handbook on the code to explain the provisions with solved examples is of

utmost importance to solicit a favorable response from users.

NNBC 000: 1994 REQUIREMENTS FOR STATE-OF-THE ART DESIGN

NNBC 000: 1994 basically describes the preface of the building code preparation and

philosophy behind the need for seismic design of buildings in Nepal. It describes and

advocates for, in general, four different levels of sophistication of design and construction,

namely, International state-of-art, Professionally engineered structures, Buildings of restricted

size designed to simple rules-of-thumb, and Remote rural buildings where control is

impractical. Accordingly, the NNBC 000: 1984 contains four separate parts describing the

requirements for each category of the design sophistication. The categorization of the design

and construction is highly influenced by the typology of buildings prevalent then in Nepal and

appears highly overwhelmed by the fact that the first ever building code should be generous to

accommodate the unsophisticated and un-engineered design. It implies the poor status of

design capability and exposure to building codes and standards. It calls for a need to not only

to revise regularly but also ascertains that the provisions are drafts standards for adoption by

NBSM. The content of NNBC 000: 1994 could have been a set of good guidelines

incorporated in local building regulations or byelaws. Since a national building code also

represents the status and sophistication of design and construction embracing latest research

and technological developments, it should not only emphasize but also concentrate only on the

International state-of-art.

A building code is a set of rules that specify the minimum acceptable level of safety for

buildings and other constructed objects. The main purpose of the building code is to protect

public health, safety and general welfare as they relate to the construction and occupancy of

buildings and other structures. The Building Code becomes the law of a particular

jurisdiction when formally enacted by the appropriate authority. Generally the codes are

meant for regulating building activity which may be recommendatory or mandatory

depending upon the authorities issuing these. Compliance to the building code is

mandatory when it is covered in Building Byelaws, Regulations, Acts, Rules, etc. issued

by the National Government and various regional or local authorities.

Building Codes are generally intended to be applied by architects and engineers, but are

also used for various purposes by safety inspectors, environmental scientists, real estate

developers, contractors, manufacturers of building products and materials, insurance

companies, facility managers, disaster management personals, and others.

The practice of developing, approving, and enforcing Building Codes is different from one

country to another. In some nations Building Codes are developed by the governmental

agencies or semi-governmental standards organizations and then enforced across the

country by the national government. Such codes are the National Building Codes, and they

enjoy a mandatory nation-wide application. In the countries, where the power of regulating

construction is vested in local authorities, a system of Model Building Codes is used.

Model Building Codes have no legal status unless adopted or adapted by an authority

having jurisdiction. In some countries, each municipality and urban development authority

has its own building code, which is mandatory for all construction within their jurisdiction.

Such buildings codes are variants of a National Building Code, which serves as model

code proving guidelines for regulating construction activity. The degree to which national

building codes and standards are enforced by law varies from country to country, as stated in

the Foreword of the Code, however it was intended that its implementation be enforced

through the Parliamentary Bill Act and concerned, local authority by-laws. In the above

scenario, it has become very important to establish the status of the building code. It is to be

noted that Building Byelaws, in relation with Building Codes, are mandatory rules and

guidelines for construction activities, issued normally by governmental agencies or

authorities with jurisdiction. Byelaws reflect the legal status of the document, and are

regulatory in nature. National Building Code or Model Building Code may be included as

an essential part of Building Byelaws; however, building codes may not contain the

byelaws. In view of this the philosophy of various levels of requirements depending upon

the design sophistication are more relevant to the byelaws to be enforced by the central or

local authorities. It is always preferable to maintain the distinct boundaries between

existing building byelaws/building regulations and building codes to avoid the confusion.

The sanctity of the building code, different from building byelaws and building

regulations, and in its turn, the seismic design of buildings shall be retained by focusing on

the international state-of-art.

It is important to understand the expressed or implied purpose of a particular design

document in order to fully appreciate its provisions. Although the basic purpose of any

seismic code is to protect life, the way that this purpose as well as any additional purposes,

presented can provide additional insight into the reasons for the presence of specific

provisions in the body of the document and its intended audience. The document shall be

free, as far as possible, of ambiguous or confusing statements or provisions. The following

paragraph describes some of issues to be resolved under NNBC 000: 1994:

The background of the development of the building code and the philosophy of seismic

design could be reasonably incorporated in the introductory part of Seismic Design of

Buildings or even in that of National Building Code itself. The requirements for the Professionally engineered structures (Part II), Buildings of restricted size designed to

simple rules-of-thumb (Part III), and Remote rural buildings where control is impractical

(Part III) along with minimum design requirements based on the flow chart (Figure 1) shall

be left out for building regulations or building byelaws. The requirements for the

International state-of-art is the main part, based on which the Seismic Design of

Buildings evolves. The need for a separate code on the remaining issues is not

justifiable.

Labeling the Building Code or part of it as draft standards belies the purpose of the

document, and weakens the position of the code executing agencies in the

enforcement of the building code.

Ambiguous statements shall be removed unless a necessary clarification is provided to

avoid the scope for misinterpretation. The return periods mentioned for the onset of

damage of a typical building and for the strength of building as 50 years and 300 years

respectively, in 1.2 Seismic Design under Part 1, need a clarification or rephrasing.

Incomplete sentences in the document of importance shall be avoided. The sentence

starting with ―The basic philosophy for…‖ and ending in blanks, in 1.2 Seismic Design

under Part 1, fails to express the principal objective of the seismic design.

The language and the format of clauses and provisions in a building code deserve a

formal/legal style rather than those of a technical report. The paragraphs following the

subheading 1.3 Other Loads under Part 1 appear like parts of a report with a little

regard for other Nepalese Standards.

Mere referring the Indian Standard Codes of Practice for design in materials like

concrete, steel and masonry does not serve the purpose of popular use and enforcement

of Nepal National Building Code. IS 456: 1978 Indian Standard Code of Practice for

Plain and Reinforced Concrete has been revised into the Fifth revision IS 456: 2000

Indian Standard Code of Practice for Plain and Reinforced Concrete. Similarly the

detailing requirements included in IS 4326: 1993 Indian Standard Code of Practice for

Earthquake Resistant Design and Construction of Buildings have been modified and

incorporated in a separate detailing code IS 13920: 1993 Indian Standard Code of

Practice for Ductile Detailing of Reinforced Concrete Structures subjected to Seismic

Forces. Since the present building code of Nepal is not explicit about which Indian

Standard Codes, referred ones or revised ones, to be adopted, the designers along with

other stake holders obviously will be in dilemma.

Due reference to Nepalese Standards without using the adjective – draft, and without

the background of their development, is most preferable. The Nepalese Standards, such

as for Wind Loads (NNBC 104: 1994), Steel Design (NNBC 111: 1994), Un-

reinforced Masonry (NNBC 109: 1994) and others shall be reviewed and improved, no

matter assistance from which international codes or publications has been derived, so

that these could be treated with respect as Nepal‘s own Standards and essential

components of the National Building Code.

Due weightage needs to be given to international coordination among the standards and

practices prevailing in different countries in addition to relating it to the practices in the

field in Nepal.

NNBC 105: 1994 SEISMIC DESIGN OF BUILDINGS IN NEPAL

Background and purpose of the code

The important information regarding the preparation of the code including its history of

development, need of the document development/improvement and the purpose of seismic

design shall be described under Foreword. Due credit shall be given to the documents and

codes, which have been used and referred in the development of the code.

The present form of Foreword needs to be enhanced with changes in terms of content and

description. The name of sub-heading - design procedure and its content stating as the

minimum design requirements for the seismic design of structures do not match; referring

just to the section under the scope does not say any thing about the design procedure nor

about the minimum requirements.

The special emphasis on the need for application of the code in conjunction with IS 4326 –

1993, under sub-heading – Related Codes is not appreciable for two reasons. Firstly, the

status of IS 4326 – 1993 in India has been changed with most of the contents being

separately transferred into newly developed codes. The statement in the para implies that

NNBC 105: 1994 can not be used without referring IS 4326 – 1993. In principle, emphasis

should be on the need of developing such basic standards or codes. Alternatively, the

relevant provisions shall be incorporated, separately as clauses, in the seismic design code

itself. Naming recent editions of IS 4326 – 1993 or other relevant national and

international codes or documents as reference materials will be more appreciated.

Moreover, details of the Standards, preferably developed for Nepal, which are necessary

adjuncts to the Seismic Design of Buildings in Nepal shall be listed elsewhere in the code.

The absence of the Commentary, forming an accompanying volume to the code, makes it

difficult to substantiate the requirement of using the code in association with the

Commentary as given under sub – heading- Commentary.

Scope

The requirements presented under the section of scope of the present code sound

conservative. Instead, the scope of the code should be general and broad in terms of

seismic load assessment on various structures and seismic resistant design of buildings.

The basic provisions shall be applicable to buildings, elevated structures, industrial

structures, dams, bridges and other structures. The scope may not include the construction

features of those buildings for which separate standards will have to address.

Terminology

The terms used in the seismic design and their definitions given in the present code should

be extended. Since the code is the sole principal document for earthquake resistant design

of buildings it will be preferable to include basic terms and their definitions related with

Earthquake Engineering in general to shed light on basic seismological aspects, as well as

Earthquake Engineering related with buildings. Basic terms related with damping, modes,

spectra, PGA, importance factor, intensity and magnitude of earthquake, liquefaction,

maximum considered earthquake, normal modes and modal characteristics, seismic weight,

zone factor and others related with basic Earthquake Engineering shall be included. It is

also necessary to incorporate more terms related with building such as base, center of mass

and rigidity, design eccentricity, base shear, bracing systems, lateral load resisting

elements, principal axes, P- effect, storey drift, storey shear, soft storey and others.

Symbols

The symbols used in the present code may be retained with the extension or revision as the

method improved or altered. However, some terms used in the symbols may be changed,

for example, fundamental time period is more suitable than translational period Ti. There is

perhaps a typographical error in meaning the symbol Fp –design seismic force for elements

and components designed in accordance with 8.

General Principles of Design

The general principles described under the present section 3 of the code could be

elaborated with the important features of seismicity and basic assumptions of seismic

design.

It is necessary to include the general principle adopted regarding the ground motion, its

features in relation with the earthquake source characterizations including the sizes of the

earthquake.

It will be favorable to describe the seismic design approach adopted in the code. The

generally accepted principle of seismic resistant design of buildings is that structures

should be able to withstand minor earthquakes without damage, withstand moderate

earthquakes without structural damage but with some non-structural damage, and

withstand major earthquakes without collapse but with some structural as well as non-

structural damage. These widely quoted objectives, however, are unstated in many codes

including the current NNBC 105: 1994. Instead, the principal objectives are stated, for

example, the Uniform Building Code UBC 1997 states an overall objective of safeguarding

life or limb, property and public welfare.

Although the definitions of minor, moderate and major earthquakes are variable, they

generally relate to the life of the structure, and the consequences of failure. The major

earthquake level defined in most of the codes of the world has a recurrence interval of 475

years, which corresponds to a 10% probability of exceedence in 50 years that is commonly

accepted to be the expected life of a building. The corresponding service level earthquake

for a typical building would have a recurrence interval of 10 years and a 99.3% probability

of being exceeded in 50 years.

There is also a need to mention about the design approach in relation with consideration of

lateral force in each of the two orthogonal horizontal directions, and approach regarding

consideration of earthquake load in vertical direction. It shall also include the approach and

corresponding provision regarding simultaneous occurrence of wind or flood, soil-

structural interaction and change in usage of the building.

Design Methods and Load Combinations

There must be a valid logical reason for need of Limit State Method of design for

reinforced concrete design and recommending Working Stress Method for other structural

materials. At this juncture of improvement, it will be preferable to explore the design

methods available and recommended in other codes and adopt the design method most

appropriate for the country. In general, most of the countries have adopted Limit State

Method or Strength Method replacing Working Stress Method for

Concrete as well as Steel, the two principle structural materials.

The provision regarding the increase in allowable soil bearing pressure by up to 50 percent

when earthquake forces are considered along with other design forces according to 4.3 of

the present code may be too un-conservative and ambiguous in application. Elaboration of

the clause is required about in what condition 50% increase can be considered, and in what

condition lower values, which are to be mentioned, of increment can be considered. IS

1893 (Part 1) : 2002 recommends the increase in allowable soil bearing pressure from 25 to

50% depending upon the soil type (hard, medium or soft ) and the type of foundations

(piles, raft, combined, isolated and well).

The design load combinations included in the present code for Working Stress Method as

well as for Limit State Method seriously require reworking. It is well recognized that the

load factors, recommended are based on the reliability levels assumed in the structures. For

example, it appears too un-conservative to have load factor for dead load as 1 and for live

load 1.3 in case of Nepal. The uncertainties due to non-uniformity of materials,

workmanship, quality control seem to be ignored in the load factor for dead load. The

uncertainties in overloading is covered by maximum 1.3 may not be practical in the

condition of Nepal. IS 456 : 2000, for example, considers 1.5 for both the dead load and

the live load. Similarly the maximum load factor value for seismic load considered is just

1.25, both in combination with 0.9 times dead load, as well as in combination with dead

load and 1.3 times live load. The value of 1.25 is too low in view of the large uncertainties

involved in assessment of the seismic load. Furthermore, the recommendation for adoption

of partial safety factors as per Table 12 of NNBC 110: 1994 contradicts the provision of

4.5 of Seismic Design Code.

Method of Seismic Design

The present seismic code recommends two methods of earthquake analysis, namely,

Seismic Coefficient Method and Modal Response Spectrum Method.

The bulk of seismic resistant buildings are designed using equivalent static lateral forces to

represent the effects of ground motion due to earthquake on buildings. It is from the

assumption that equivalent static forces can be used to represent the effects of an

earthquake by producing the same structural displacements as the peak earthquake

displacement response. The application of this method is limited to reasonably regular

structures. The present code restricts the use of this method for structures up to 40 m

height, and should also mention the condition of regularity.

The dynamic analysis shall not be confined to the response spectrum method. There must

be an optional provision for Time History Analysis also. The conditions for need of using

Modal Response Spectrum Method (Dynamic Analysis) are listed, which are basically

related with irregular configuration. Due to absence of definition and classification of

irregularity, the users of the code will be confused. It is desirable to include clauses that

define and describe different types of irregularity (horizontal, vertical, stiffness, mass,

geometric and others). By such definitions a clearer picture and effect of soft storey and

weak storey will be available.

The formula for determination of seismic coefficient has been changing in the seismic

codes of the world. However, the base shear due to ground motion has all the time been the

product of the seismic coefficient and the mass of the structure. The principal code factors

used in deriving static lateral forces, for a long time, have basically been:

Z A numeric value representing the seismic zoning

I An importance factor representing the importance of the structure, especially in

terms of use following a major earthquake.

C A factor representing the appropriate acceleration response spectrum value.

S A factor representing the effect of local soil conditions on the spectral response of

the ground

W The mass of the structure, including an assessment of live load

K A factor representing the performance of the structure depending on the brittleness

or ductility of the structure

These values are combined in general form for base shear:

V = ZICKSW

This formula for base shear has been for a long time popular. However in course of

evolution the formula for the seismic coefficient has been changing. The formula for the

seismic coefficient presented in the present NBE 105: 1994 considers all the above factors

except S-the factor representing the effect of local soil conditions on the spectral response

of the ground. This effect has been considered, like in other codes, in the response spectra

drawn for different (basically three) types of soil. Thus the expression for the seismic

coefficient given in equation 8.1. Similarly, the equation 8.2 for the expression for the

design response spectrum, in which the ordinate of the basic response spectrum for the

natural time period is multiplied by ZIK.

It has been a trend in the codes of the world to drop the performance factor K and replace it

by reciprocal of R, response reduction factor, a factor dependant on the building type and

its ductility level. The adoption of the response reduction factor leads to a realistic values

of acceleration from which the design forces are obtained by dividing the elastic forces by

it. It implies that the design force is much lower than what can be expected in the event of

a strong earthquake (Jain 2003).

The replacement of the factor K by the factor 1/R may result into a logical estimation of

the seismic coefficient, and alternate expressions derived in recent editions of codes or

documents like NEHRP shall be given a thought for the new edition of the code.

Computing dynamic response instead of using static forces is becoming increasingly

common as higher powered computing facilities are being available in design offices.

Since there is no restriction of building height and irregularity the dynamic analysis

appears to be simpler in application and yields more logical and accurate results. However,

special care shall be taken into consideration about conservative provision in some

international codes. Some codes require checking of the dynamic analysis results by

seismic coefficient method. Some documents like IS 1893 (Part 1) : 2002 require

comparing the base shear with the base shear calculated using the fundamental time period

calculated using the empirical formula recommended for static approach, and if the base

shear from dynamic analysis is less than the base shear calculated using the time period

from the empirical formula, all the dynamic responses shall be up-scaled multiplying by

the ratio of the two base shears. It again implies the dominance of the seismic coefficient

method over the dynamic analysis.

Seismic Hazard Level and Response Spectrum

Estimate of the design ground motion is the most important and complicated part of the

seismic design code development. Estimates of the design ground motion are necessarily

controversial and uncertain. It is more important to the structural designer that this is

understood than for him to attach some particular significance to any ground motion

parameter used in his design. However there is a strong argument for conservatism in the

assessment of ground motion input, and the use of high confidence level.

NNBC 105: 1994 does not present any elaborate information on the seismicity of the

country. It would be favorable to include at least maps showing epicenters of past

earthquakes, principle tectonic features, geological features including principal lithological

groups, and seismic zones, all of which are well documented by the Department of Mines

and Geology, Nepal. Pandey et al. (2002) has presented seismic hazard map of Nepal as a

result of probabilistic seismic hazard analysis. The document presents the contour of

seismic hazard at the bedrock of Nepal for a return period of 500 years, indicating 10%

probability of exceedence in 50 years.

The design values of ground motion parameter such as Peak Ground Acceleration (PGA)

for different regions of the country are presented either in a tabular form (GB 50011-2001)

or attaching relevant maps like in IBC 2006 in the codes. It is necessary to do the same in

NNBC 105: 1994 also since the seismic hazard for the code was determined based on the

probabilistic seismic hazard analysis. The seismic codes adopting probabilistic approach of

hazard estimation use the hazard levels in terms of Maximum Considered/Capable

Earthquake (MCE) as in NEHRP (2003) and IBC (2006), and Design Basis Earthquake

(DBE) as in ATC (1978) and UBC (1997). The MCE and DBE represent 2% probability of

exceedence in 50 years with a return period of 2500 years and 10% probability of

exceedence in 50 years with a return period of 475 years respectively.

The seismic hazards considered in earlier editions of NEHRP and UBC 97 (1997) had a

recurrence interval of 475 years (Design Basis Earthquake) corresponding to a uniform 10

percent probability of exceedance in 50 years, which is commonly accepted to be expected

life of a building. The NEHRP(1997) and IBC2000(2000) had changed the Design Basis

Earthquake(DBE), and since then have been using the Maximum Considered Earthquake

(MCE) to represent the seismic hazards in the provisions.. The MCE represents the seismic

hazard that has a recurrence interval of 2500 years corresponding to a uniform 2%

probability of exceedence in 50 years. The design earthquake according to the provisions

of NEHRP(2003) and IBC 2006 (2006) is two-thirds of the MCE. Comparison of the

provisions of 1994 or older editions with 1997 or later editions of the NEHRP Provisions

reveals that, a structure designed by the 1994 or older editions of NEHRP Provisions is

believed to have a low likelihood of collapse under an earthquake that is one and one-half

times (reciprocal of two-third) as large as the design earthquake of those documents. The

same change has taken place from UBC 97 (1997) to IBC 2000 (2000). This major change

in association with other provisions indicates the newer versions of the documents tend to

be more conservative.

The seismic loading in NNBC 105: 1994 is set at a seismic hazard level having a return

period of 50 years, which corresponds to a probability of exceedence less than 45% in 30

years, which had been estimated as the economic life of a structure in Nepal, as presented

by Beca Worley International et al.(1993). The document as well reveals that the seismic

hazard level was set to be at a level approximately equal to that defined in the Indian

Standard, that is, IS 1893: 1984. The design earthquake level set hence is too un-

conservative and strongly needs a major revision for the following reasons:

v. The service life of buildings in Nepal estimated as 30 years is far from reasonable;

instead it must be 50 years.

vi. It is unfair to set the seismic hazard level for Nepal heavily banking upon the

earthquake level stipulated in IS 1893: 1984, which has already been revised into IS

1893 (Part 1): 2002 with a different value of design earthquake value. The Indian

Standard has yet to adopt probabilistic format of seismic hazard analysis.

vii. The provisions in the present code have been developed in reference with mainly low

rise buildings with short natural periods, where as long period structures are

increasingly becoming prevalent.

viii. The seismic design lateral load calculated for short period structures as 0.08, when

compared with the basic horizontal seismic coefficient for zone V of IS 1893: 1984,

found the same as 0.08. But the value according to the revised IS 1893 (Part 1): 2002

will be 0.09 against 0.08.

The response spectra and the zoning factors largely depend on the design earthquake

levels, and hence will be different as the seismic hazard levels change.

The broad classification of soil conditions into three types is universally accepted.

However, the definition and requirements of each type of them shall be more practical and

recognizable.

Static Method (Seismic Coefficient Method)

The seismic base shear V along any principal direction is determined by the expression:

V = Cd Wt

In which Cd is the design horizontal seismic coefficient, and Wt is the seismic weight of the

building. However, the expression given by equation 10.1 is not supplemented with what

stands for the notation Wt . Moreover, it requires the definition of the seismic weight of the

building. There is also a need to describe how the seismic weight of the building is

calculated in terms of seismic weight of floors, which has to be referred, although briefly

introduced under the section 6 Seismic Weight. It should further be elaborated with the

rules for lumping of weights.

The distribution of the design base shear along the height of the building is carried out in a

linear manner, that is, the design lateral force at floor level i is calculated by:

Fi = V Wi hi/ΣWi hi

The Indian Standard IS 1893 has long been adopting the parabolic distribution,

corresponding to which the design lateral force, equivalent to IS 1893 (Part 1):2002, at

floor level i is calculated by:

2

1

2

ii

n

i

iii

hW

hWVF

Both of the above distributions are at the extremes. The linear distribution is true for

basically stiff structures having a natural period of 0.5 seconds or less (approximately for

up to 5 storeys of the building). The parabolic distribution is applicable basically for

flexible structures having a natural time period of 2.5 seconds (approximately for 25

storeys and more of the building).

The distribution of the horizontal forces over the height of a building is generally a quite

complex because these forces are the result of superposition of a number of natural modes

of vibration. The relative contributions of these vibration modes to the total forces depends

on a number of factors, which include shape of the ground motion response spectrum,

natural periods of vibration of the building, and the vibration mode shapes, which in turn

depend on the mass and stiffness distribution over the height of the building. Based on it,

ATC 3-06 (1978) has provided the reasonable and simple formula to obtain the horizontal

earthquake force distribution in buildings with regular variation of mass and stiffness over

the height as follows:

k

ii

n

i

k

ii

i

hW

hWVF

1

in which, k is an exponent related to the building period as follows:

For buildings having a period of 0.5 seconds or less, k = 1.

For buildings having a period of 2.5 seconds or more, k = 2.

For buildings having a period between 0.5 and 2.5 seconds, k may be taken as 2 or may be

determined by linear interpolation between 1 and 2.

In view of the changing characters of the buildings, increasingly departing from the low

rise situation, the linear distribution provision in the code will be again un-conservative,

and hence needs a change. It is to note that the American codes have been adopting the

distribution formula developed by ATC 3-06 (1978).

The provision regarding the direction of forces under sub-heading 8.2.1 shall be rewritten

to clarify to the effect that the structure shall be designed for design earthquake load in one

horizontal direction at time, indicating the design earthquake load will not be applied

simultaneously in both of the orthogonal directions.

The design eccentricity provision should have been provided together with the clause on

the horizontal shear distribution or under Torsion. The design eccentricity, ed is

recommended to be calculated depending upon the value of ec ( eccentricity between the

locations of the center of mass and the center of rigidity) in relation with b, the maximum

dimension of the building perpendicular to the direction of the earthquake force. Three

separate conditions and corresponding values to be used or calculated are presented. The

design eccentricity is required to calculate the design torsional moment to consider its

effect in the distribution of lateral forces at each level. The purpose of the provision on the

design eccentricity would have better been served by a clause on Torsion to the effect ―The

distribution of lateral forces at each level shall consider the effect of the torsional moment

resulting from eccentricity ec between the locations of the center of mass and the center of

rigidity‖. It should be followed by a complimentary clause on Accidental torsion, to the

effect ―In addition to the torsional moment, the distribution of lateral forces also shall

include accidental torsional moments, caused by an assumed displacement of the mass

each way from its actual location by a distance equal to 5% of the dimension of the

structure b, perpendicular to the direction of the applied forces. Alternatively, The design

eccentricity would be algebraic sum of the factored eccentricity and the accidental

eccentricity each way. Accordingly, the expression for the design eccentricity for ith

floor

would be, assuming 1.5 as the factor for the eccentricity:

edi = 1.5 eci ± 0.05 bi

Dynamic Method (Modal Response Spectrum Method)

The provisions presented in the present code are not adequate. There is a need for clauses

for free vibration analysis to obtain the natural periods (T) and mode shapes (φ). The

present provision for the numbers of the modes to be considered in 11.2 needs elaboration

including explanation how to check if the 90% of the mass is participating or not. It shall

be done by introduction of formulae along with definitions of modal mass and modal

participation factors. There are serious lapse of provisions for modal combination methods,

methods for determination of design lateral forces at each floor in each mode and due to all

modes considered, and also expressions for storey shear forces in individual mode and due

to all modes considered.

The para 11.3.1 mentions about need to use an established method for combination of

modal effects. An ambiguous word like established method shall be avoided and replaced

by the name of the method/s to be applied. The definition of closely spaced modes as given

in para 11.3.3 is incorrect. Closely spaced modes are defined as those of its natural modes

of vibration whose natural frequencies differ from each other by 10 % or less of the lower

frequency, not if their frequencies are within 15%.

Deformations

The primary clause for deformation due to earthquake forces is the storey drift limitation,

which shall not exceed 0.004 times the storey height. The sense of this limitation may be

implied from the provision given under 9.2.2. For the purpose of displacement

requirements only, the seismic forces obtained from the fundamental time period of the

building by static or dynamic approach may be used. The provision under 9.1 shall be

applicable for the separation between two adjacent buildings or two adjacent units of the

same building. The separation must be provided by a distance equal to the sum of the

calculated storey displacements multiplied by 5/k or by R, if the performance factor k is

replaced by response reduction factor R. rewritten as for the separation. It shall further be

supplemented by the provision that if the floor levels of the two adjacent units or buildings

are at the same elevation levels, the factor 5/k or by R may be further replaced by 10/k or

R/2 respectively. Accordingly it is preferable to rearrange the sub-clauses under this

section.

Requirements for Other Components and Elements

The provisions under section 12 shall elaborate, beyond the general statements, how the

requirements are achieved. This section also shall present provisions for important

components like foundations, projections and other parts of the buildings.

References

1. ATC 3-06 (1978) Tentative Provision for the Development of the Seismic Regulations for

Building, Applied Technology Council, USA.

2. Beca Worley International in association with others (1993), Seismic hazard Mapping and

Risk Assessment for Nepal, UNDP/UNCHS(Habitat) Subproject, Nep//88/054/21.03

3. GB 50011-2001 Code for Seismic Design of Buildings, National Standard of the People‘s

Republic of China, Beijing, PRC.

4. IBC 2006 International Building Code, International Code Council, USA.

5. IS 13920: 1993 Indian Standard Code of Practice for Ductile Detailing of Reinforced

Concrete Structures subjected to Seismic Forces, Bureau of Indian Standards, New Delhi,

India.

6. IS 1893 : (Part 1) 2002 Indian Standard Criteria for Earthquake Resistant Design of

Structures Part 1 General Provisions and Buildings (Fifth Revision), Bureau of Indian

Standards, New Delhi, India.

7. IS 1893: 1984 Indian Standard Criteria for Earthquake Resistant Design of Structures,

Bureau of Indian Standards, New Delhi, India.

8. IS 4326: 1993 Indian Standard Code of Practice for Earthquake Resistant Design and

Construction of Buildings, Bureau of Indian Standards, New Delhi, India.

9. IS 456: 1978 Indian Standard Code of Practice for Plain and Reinforced Concrete, Indian

Standards Institution, New Delhi, India.

10. IS 456: 2000 Indian Standard Code of Practice for Plain and Reinforced Concrete (Fourth

Revision), Bureau of Indian Standards, New Delhi, India.

11. IS 800: 1984 Indian Standard Code of Practice for General Construction in Steel, Bureau

of Indian Standards, New Delhi, India.

12. Jain, S. K. Review of Indian Seismic Code IS 1893 (Part 1): 2002, the Indian Concrete

Journal, November 2003, India.

13. NNBC 000: 1994 Nepal National Building Code Requirements for State-of-the art Design

an Introduction, HMG of Nepal, Ministry of Physical Planning and Works, DUDBC,

Kathmandu, Nepal, 2060.

14. NNBC 102: 1994 Nepal National Building Code Unit Weight of Materials, HMG of


15. NNBC 103: 1994 Nepal National Building Code Occupancy Load (Imposed Load), HMG

of Nepal, Ministry of Physical Planning and Works, DUDBC, Kathmandu, Nepal, 2060.

16. NNBC 104: 1994 Nepal National Building Code Wind Load, HMG of Nepal, Ministry of

Physical Planning and Works, DUDBC, Kathmandu, Nepal, 2060.

17. NNBC 105: 1994 Nepal National Building Code Seismic Design of Buildings in Nepal,

HMG of Nepal, Ministry of Physical Planning and Works, DUDBC, Kathmandu, Nepal,

2060.

18. NNBC 106: 1994 Nepal National Building Code Snow Load, HMG of Nepal, Ministry of


19. NNBC 109: 1994 Nepal National Building Code Masonry: Unreinforced, HMG of Nepal,

Ministry of Physical Planning and Works, DUDBC, Kathmandu, Nepal, 2060.

20. NNBC 110: 1994 Nepal National Building Code Plain and Reinforced Concrete, HMG of


21. NNBC 111: 1994 Nepal National Building Code Steel, HMG of Nepal, Ministry of


22. NEHRP 2003 Recommended Provisions for the Development of Seismic Regulations for

New Buildings, Building Seismic Safety Council, Federal Emergency Management

Agency, USA.

23. Pandey, M. R., Chitrakar, G. R., Kafle, B., Sapkota, S. N., Rajaure, S. & Gautam, U. P.

(2002), Seismic Hazard Map of Nepal, National Seismological Centre, Department of

Mines and Geology, His Majesty's Government of Nepal, Kathmandu

24. UBC 1997 Uniform Building Code, INTERNATIONAL Conference on Building Officials,

Whittier, California, USA.

Appendix 5- Review of NNBC 101, 102, 103, 104, 106, 107, 108, 109

NNBC 101:1994

Materials Specifications

This standard deals with the requisite quality and effectiveness of construction materials used

mainly in building construction. It also deals with the storage of materials where storage has

relevance to strength.

A list of Nepal Standards (NS) for key materials is provided. For those materials for which Nepal

Standard does not exist, a list of Indian Standard (IS) has been included. The use of appropriate,

adopted or new materials is encouraged, provided these materials have been proven to meet their

intended purposes. Those materials which are not covered by the code also may be used in

building requiring National Building Code compliance provided these materials are equivalent, or

better in quality, strength, effectiveness, fire resistance, durability, safety, maintenance and

compatibility. Prior to the use of such materials, it shall be the responsibility of the building

owner, or the authorized representative of the building owner, to obtain proof of equivalency.

If recycled /used materials meet the requirements of the standard, they may also be used. The

code does not specify or refer to the methods of quality tests of materials and works. The reference

methods and Standard Operating Procedures shall be referred.

NBC 102:1994

Unit Weight of Materials

This Nepal Standard for unit weight of Materials adopts the Indian Code IS:875(Part 1)-1987 code

of Practice for Design loads ( Other than Earthquake) for building and structures, Part 1- Dead

loads-Unit weight of building materials and stored materials.(second revision).

Since the table of unit weight of material not provided in the code, the code is not convenient to

use. Unit weight of materials is provided in Nepal Standard, so table of unit weight of material

from NS can be used.

NBC 103:1994

Occupancy Load (Imposed Load)

The Nepal Standard for Occupancy Load adopts the Indian Code IS:875(Part 2)-1987 code of

Practice for Design loads ( Other than Earthquake) for building and structures, Part 2- Imposed

Load.(second revision).

It is considered imperative that a table of the occupancy classification and corresponding loading

is provided in the code. The Table for the imposed load for occupancys should be provided for

convenience for the users.

In Nepal Standard NS , different tables such as Table1-Imposed floor loads for different

occupancies, reduction in imposed loads on floors, Table 2- Imposed loads on various types of

roofs, Table 3- horizontal loads on parapets, parapet walls and balustrades are provided which can

be used in NBC 103:1994 to make it independent.

Uniform live loads. The live loads used in the design of buildings and other structures shall be the

maximum loads expected by the intended use or occupancy but shall in no case be less than the

minimum distributed loads required by provided table.

Partition loads. In office buildings and in other buildings where partition locations are subject to

change, provision for partition weight shall be made, whether or not partitions are shown in

construction documents, unless the specified live load exceeds 3.83 kN/m2. Such partition load

shall not be less than a uniformly distributed live load of 0.96 kN/m2.

Change in occupancy load

As we know in Nepal, the use of buildings is changed from one occupancy classification to

another occupancy, for example from residential to schools or store; from Hotel to Super Market

or Office . In such cases, the occupancy load will be changed. It's an important aspect of any

building design, and occupancy load calculations are made as per different occupancies. At all

stages of the operation of the building, it is essential that the safety of the life and p[roperty

including the building is safeguarded and comply with the requirements of the Code for the

concerned class of Occupancy Load. If the safety is not warranted, prohibition of change of

occupancy class of the building should be imposed. .

NNBC 104:1994

Wind Load

The Nepal Standard on ―Wind Load‖ comprises the Indian Standard IS:875(Part 3)-1987 code of

Practice for Design Loads ( Other than Earthquake) for building and structures (Second Revision)

with amendments to ensure the requirements of Nepalese context, particularly wind zoning map

of Nepal.

The available wind data in Nepal is inadequate both in terms of spatial distribution, intensity and

duration. Modern wind design codes are based on the peak gust velocity averaged over a short

interval of about 3 seconds that has a 50 year return period.

On the base of wind velocity, Nepal has been divided into two regions: (a) The lower plains and

hills, and (b) the mountains. The first zone generally includes the southern plain of Tarai, the

Kathmandu valley and those regions of the country generally below an elevation of 3,000 metres.

The second zone covers all the areas above the 3000 metres.

For the Nepalese plains, a continuum with Indian plains, a basic wind velocity of 47m/s has been

adopted. In the higher hills, a basic wind velocity of 55 m/s selected.

In the wind map of Nepal no basic wind speed is indicated. Similarly, wind data table is not

provided.

While making the present code, some amendments have been done to IS:875(Part 3)- 1987

comprising of replacement of terminology like ―Indian‖ to ―Nepal or ―code‖ with ―standard‖,

delation of some clauses and sentences, and so on.

This type of amendments has created discomfort for using the NBC 104:1994. In Nepal Standard

NS 500, the map of Nepal has indicated the basic wind speed and different factors. Nepal National

building code may provide detailed required data and information in the code itself so that it

becomes convenient for th eusres.

Formatted: Justified

Wind Speed and Pressure

In general, wind speed in the atmospheric boundary layers increases with height from zero at the

ground level to a maximum at a height called the gradient height. Wind speed at any height never

remains constant and it has been found convenient to resolve its instantaneous magnitude into an

average or mean value and a fluctuating component around this average value. The average value

depends on the averaging time employed in analyzing the meteorological data and this averaging

time varies from a few seconds to several minutes. The magnitude of fluctuating component of

wind speed which is called gust, depends on the averaging time. In general, smaller the averaging

interval, greater is the magnitude of the gust speed.

Basic Wind Speed

Basic wind speed is based on the peak gust velocity averaged over a short time interval of about 3

seconds and corresponds to a mean height above the ground level in an open Terrain. Basic wind

speed for the zone is taken from map of Nepal.

Design Wind Speed (Vz)

The Design Wind Speed is expressed as follows:

Vz = VbK1K2K3

Where Vz – design wind speed at any height z in m/s;

K1 – probability factor (risk coefficient)

K2 – terrain, height and structure size factor

K3 – topography factor

Design Wind Pressure

The design wind pressure at any height above mean ground level is obtained from the expression:

Pz = 0.6 Vz2

Where pz – design wind pressure in N/m2 at height z, and

Vz – design wind velocity in m/s at height z.

In IS : 875(Part 3): Wind Loads on Buildings and Structures, the proposed draft commentary

prepared by Dr. Prem Krishna, Dr. Krishen Kumar, Dr.N.M. Bhandari suggested to analyses the

design wind pressure pd assign following equation:

pd = K

d. K

a. K

c. p

z

where Kd = Wind directionality factor

Ka = Area averaging factor

Kc = Combination factor

Ka

should be taken as 1.0 when considering local pressure coefficients.

Kd - Considering the randomness in the directionality of wind and recognizing the fact that pressure

or force coefficients are determined for specific wind directions, it is specified that for buildings,

solid signs, open signs, lattice frameworks, and trussed towers (triangular, square, rectangular) a

factor of 0.90 may be used on the design wind pressure.

For circular or near – circular forms, this factor may be taken as 1.0.

For the cyclone affected regions also, the factor Kd shall be taken as 1.0.


Formatted: Justified, Indent: Left: 0.5", Firstline: 0.5"

Area Averaging Factor, Ka

Pressure coefficients are a result of averaging the measured pressure values over a given area. As

the area becomes larger, the correlation of measured values decrease and vice-versa. The decrease

in pressures due to larger areas may be taken into account as given in Table 1.

Table 1: Area averaging factor (Ka)

Tributary Area (A) (m2

) Area Averaging Factor (Ka)

≤ 10 1.0

25 0.9

≥ 100 0.8

The Russian Code and Standards (SNIP) recommend that wind load on tall building shall be

estimated as the sum total of average and pulsation excitations. The design wind load can be

expressed as:

w = wc + wp

wc = wo.k.c,

wp = 1.4 wph(z/h)ξ

where wc – average wind pressure, wp – wind pressure due to pulsation; w0- nominal wind

pressure; wph – nominal pulsation wind pressure at the top height of the building; k- height factor;

ξ – dynamic coefficient;z- height at which pulsation wind pressure is being determined.

Nigerian standard code of Practice (NSCP) suggest to analyse the design wind load using

following expression:

P = fs.qo.ce

Where qo – the nominal wind pressure;

vo- the nominal wind velocity;

fs – shape factor

ce – the pressure coefficient

NBC 106:1994

Snow Load

The code on ―Snow Load‖ comprises the Indian Standard IS: 875 (Part 4) 1987: CODE OF

PRACTICE FOR DESIGN LOADS (OTHER THAN EARTHQUAKE) FOR BUILDINGS AND

STRUCTURES (second revision) along with new improvements and amendments to ensure the

requirements of the Nepalese context.

In this code, 0.1 to 0.3.2 has been deleted from the original version to match the code with the

Nepalese lifestyle. The added revisions are related to snow load in the northern snow-covered

districts like Dolakha, Darchula, Bajhang, Humla, Mugu etc. The country is divided into five

categories based on the physiographic regions. Of these five physiographic regions, the Tarai, the

Siwaliks and the middle mountains, do not experience snow fall. High mountains get snow two or

three months of a year. The High Himalayas always have snow cover throughout the year. Snow

load could be experienced once in a whilw within Kathmandu Valley, and the areas around

Kathmandu Valley experience snow load quite often.

At high altitude, roofs are built flat with mud floor placed over timber planks or split pieces of

wood. A slope is not provided because the wind speed is high and the rainfall is sparse. Only a

nominal slope that is just enough to drain the melted snow and rain water is provided. Snow

accumulates on the roof and the narrow space between the adjacent buildings also filled. Snow

accumulated on the roof is removed manually.

No historical snow data exist. The Snow and Glacier Hydrology have just recently started to

collect data in high altitude region. Depth, density and water equivalent are monitored. However,

the data obtained from the projects is far less than that of the verbal inquiry. So, the concerned

personnel and institutions are being requested to collect data from in depth studies and inquiries of

the knowledgeable people of the locality.

Snow Load in Roof

The Design snow load is obtained by multiplying the snow load on the ground, S0 by the shape

coefficient μ,

S= μ S0

where s - design snow load in Pa on plan area of roof,

μ - shape coefficient and

S0 - ground snow load

The code has done some amendments in IS: 875(Part 3)-1987 with replacement of some

terminology, and sentences

In the code, it is mentioned that the most favorable slope for both wind and snow is taken as 2:1.

This type of amendments does make it convenient to the users.

Since the middle mountain zones also experience snow fall sometimes, but the code has

demarcated it as ―no snow fall zone‖. There is a gap in data as such in this region.

Comparisons with other codes

As per National Building Code of Canada 1990, the Snow load on a roof or any other building

surface subject to accumulation shall be calculated from the formula

S = Ss(CbCwCa)+Sr

where

Ss - the ground snow load in kPa

Sr -s associated with rain load in kPa

Cb - the basic roof snow load factor of 0.8,

Cw - the wind exposure factor,

Ca - the accumulation factor. .

The Canadian Code presents snow distribution factors on various types of roofs which can be

applied universally with reliability and need only be tempered in detail with local experience.

In Russian code SNIP 2.01.07-85, the Snow load is calculated by formula

S=Sg x μ

Some properties of snow

A careful assessment of the snow load is required to avoid both unnecessary construction cost and

undue risk of failure. Snow loads on roofs vary widely according to geographical location, site

exposure and shape of the roof.

Snowflakes of falling snow consist of ice crystals with their well-known complex pattern. Owing

to their large surface area to weight ratio they fall to the ground relatively slowly and are easily

blown by the wind.

Freshly fallen snow is very loose and fluffy, with a specific gravity of about 0.05 to 0.1 (1/20th

to

1/10th

of water). Immediately after landing, the snow crystals start to change: the thin, needle-like

projections begin to sublime and the crystals gradually become more like small irregularly shaped

grains. This results in settlement of the snow and after a few days the specific gravity will usually

have increased to about 0.2. This compaction further increases and specific gravities of about 0.3

will often have been attained after about a month, even at below-freezing temperatures. Longer

periods of warm weather as well as rain falling into the snow (a possibility that must be included

in proper design loads) may increase this density even further.

As a simple rule for estimating loads from snow depths, the specific gravity can be considered to

be about 0.2 to 0.3. In other words, each inch of snow represents a load of about 5-8 Kg/m2.

Accumulation of Snow on Roofs

In perfectly calm weather, the falling snow would cover roofs and the ground with a uniform

blanket of snow. If this calm continued, the snow cover would remain undisturbed and the

prediction of roof loads would be relatively simple; the design snow load could be considered

uniform and equal to a suitable maximum value of the ground snow load.

Truly uniform loading conditions, however, are rare. In most regions, snowfalls are accompanied

or followed by winds, and the snowflakes, having a large surface area to their weight, are easily

transported horizontally by the wind. Consequently, since many roofs are well exposed to the

wind, accumulation of snow will depend on the wind and configuration of the roof itself. Over

certain parts of roofs the wind speed will be slowed down sufficiently to let the snow "drop out"

and accumulate in drifts.

The roofs situated below an adjacent higher roof are particularly susceptible to heavy drift loads

because the upper roof can provide a large supply of snow. Canopies, balconies and porches also

fall into this category and the loads that accumulate on these roofs often reach a multiple of the

ground load depending mainly on the size of the upper roof. The distribution of load depends on

the shape of these drifts which varies from a triangular cross-section (with the greatest depth

nearest to the higher roof) to a more or less uniform depth.

Flat roofs with projections such as penthouses or parapet walls often experience triangular snow

accumulations that reach the top of the projections on the building.

Peaked and curved roofs subjected to winds at approximately right angles to the ridge provide

aerodynamic shade over the leeward slope. This sometimes leads to heavy unbalanced loads, since

most of the snow is blown from the windward slope to the leeward slope, producing loads that

exceed the ground load on occasions. Curved roofs show similar or even more unbalanced

distributions (little snow on top and heavy snow near the base of the arch).On the other hand it is

true that many small peaked roofs on residences, in exposed areas, usually (but not always)

accumulate little snow compared with that on the ground.

Redistribution of Load

Redistribution of snow load can occur not only as a result of wind action. On sloped roofs there

are two problems connected with the melting of snow at temperatures slightly below freezing.

Firstly, melt water can refreeze on caves and cause high ice loads (also water back-up under

shingles). This can at least partly be solved by taking steps to, decrease the heat loss from the

upper parts of the roof. Secondly, if a roof slopes and drains on to a lower one, melt water

sometimes accumulates by refreezing on the lower roof or it is retained in the snow.

Responsibility of Designer

Code requirements for snow loads must necessarily be rather general, and consequently the

designer should not apply the loads given in the Code without considering the effects of the shape

and exposure of the roof. The designer should, therefore, consider in each case the building site,

size and shape, where drifts are likely to occur on the roof drainage, and so on.

NNBC 109:1994

Masonry: Unreinforced

1. Introduction

1. NBC 109:1994 Masonry: Unreinforced

1.1 Introduction

Nepal National Building Code NBC 109:1994 covers the structural design aspect of

unreinforced masonry elements in buildings. It also deals with some aspect of earthquake

resistant design of buildings. Reference to seismic zoning, seismic coefficients, important

factors and performance coefficients are adopted as per NBC 105-1994: Seismic Design of

Buildings in Nepal.

It was quoted in the Code that this code should be read in conjunction with the Indian

Standard IS:1905-1987 Code of Practice for Structural Use of Unreinforced Masonry

(Third Revision). This provision makes it (Code NBC 109:1994) dependent on

IS:1905-1987.

Materials used in Masonry construction are taken in accordance with NBC 101-1994

Material Specification and masonry units as per NS 1/2035 Brick Masonry.

Special considerations for earthquake resistance considered for site consideration were

made as per NBC 108-1994: Site consideration.

1.2 DESIGN CONSIDERATION OF DIFFERENT CODES:

1.2.1 Building Code Requirements for Masonry Structures (ACI 530-02/ASCE 5-02/TMS

402-02)

The code provides minimum requirements for the structural design and construction of

masonry units bedded in mortar using both allowable stress design as well as limit state

design (strength design) for unreinforced as well as reinforced masonry. The topic on

strength design is a new addition to the previous edition of this code (ACI 530-99/ASCE 5-

99/TMS 402-99). In strength design, more emphasis is laid on reinforced masonry than

unreinforced masonry. An empirical design method applicable to buildings meeting

specific location and construction criteria is also included.

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1.2.2 International Building Code 2000

The International Building Code 2000 (ICC 2000) is designed to meet the need for

modern, up to date building code addressing the design of building systems through

requirements emphasizing performance. The provisions of this code for the design of

masonry members have been borrowed from ACI 530-02/ASCE 5-02/TMS 402 -02.

1.2.3 Euro code 6: Design of Masonry Structures

This code specifies a general basis for the deign of buildings and civil engineering works

in unreinforced and reinforced masonry made with clay and concrete masonry units laid in

mortar. Limit State Design method has been adopted throughout this code. However, Euro

Code 6 does not cover the special requirements of seismic design.

1.2.4 Indian Standard – Code of Practice for Structural Use of Unreinforced Masonry (IS:

1905-1987)

The provisions of this code are similar to those of BS 5628: Part 1:1978. The Indian

Standard provides recommendations for structural design aspect of load bearing and non

load bearing walls using unreinforced masonry only. Design procedure adopted throughout

the code is allowable stress design, along with several empirical formulae. The code refers

to IS: 4326 for strengthening unreinforced masonry buildings for seismic resistance and

does not provide any calculation for the design of reinforcement.

1.3 Design Philosophies

The specification laid down in clause 5.1 to 5.5.5 of Indian Standard IS:1905-1987 is

adopted in this code.

The design philosophies of various codes have been compared with regard to their design

assumptions and assumed factor safety in following section:

1.3.1 Empirical Design

Empirical rules and formulae for the design of masonry structures were developed by

experience and traditionally, they have been used as a procedure, not as a design analysis

for sizing and proportioning masonry elements. This design procedure is applicable to very

simple structure with limitations on building height proportions and horizontal loads such

as due to wind and earthquake. Indian Standards mixes empirical procedure with allowable

stress design method.

1.3.2 Allowable stress design

Allowable stress design states that under working loads, the stresses developed in a

member must be less than the permissible stresses. In case of unreinforced masonry, it is

assumed that tensile stresses, not exceeding allowable limits, are resisted by the masonry.

For the reinforced masonry, tensile of masonry is neglected.












1.3.3 Strength Design of Limit State design

Strength design requires that masonry members be proportional such that the design strength

equals or exceeds the required strength. Design strength is the nominal strength multiplied by a

strength reduction factor (θ). The procedure has been adopted by the ACI code, IBC 2000 and

the New Zealand code, and more emphasis has been laid on reinforced masonry in all these

three codes. In these codes, on the basis of the following assumptions, the strength of

reinforced masonry members is calculated.

a. There is strength continuity between the reinforcement, grout and masonry.

b. The maximum usable strain (emu) at the extreme masonry compression assumed to be

0.0035 for clay masonry and 0.0025 for concrete masonry. The New Zealand code

specifies that the maximum usable strain will be 0.008 for confined concrete masonry.

c. Reinforcement stress below specified yield strength (fy) shall be taken as Es times steel

strain. For strains greater than that corresponding to fy, stress in reinforcement shall be

taken equal to fy.

d. The tensile strength of masonry shall be neglected in calculating flexural strength but shall

be considered in calculating deflection.

1.4 COMPARISON CONCEPTS FOR UNREINFORCED MASONRY

1.4.1 Allowable Stress Design

1.4.1.1 Axial Compression

Axial compression on masonry arises due to vertical loads, especially from dead load and

live load. Compression tests of masonry prisms are used as the Basis for determining

specified compressive strength of masonry fm, which is further modified for slenderness,

eccentricity, shapes of cross-section, etc. to derive allowable compressive stress values.

In ACI code, calculated compressive stress (fa) should be less than the allowable

compressive stress Fa which is obtained by multiplying fm with 0.25 and slenderness ratio,

R. The factor 0.25 accounts for material uncertainty and reduces fm to working stress level.

R is the capacity reduction factor for slenderness.

Slenderness can affect capacity either as a result of inelastic buckling or because of

additional bending moments due to the deflection. Applied axial load must be less than

25% of the Euler buckling load. Therefore, according to ACI code, the permissible value is

function of slenderness ratio whereas the limiting value of axial load depends on both

slenderness ratio as well as eccentricity of the axial load.

In IS: 1905 code a stress reduction factor (ks) is multiplied with the basic compressive

stress for slenderness ratio of the element and also the eccentricity of loading. The basic

compressive stress is either determined from prism test values or a standard table which is

based on compressive strength of unit and mortar type.

1.4.1.2 Axial Compression with Flexure

Masonry members are generally subjected to flexural stresses due to eccentricity of loading

or application of horizontal loads such as wind and earthquake. According to the ACI

code, if a member is subjected to bending only, calculated bending compressive stress fb



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should be less than allowable bending stress fb in masonry, taken as 0.33fm which is 1.33

times the basic compressive stress allowed for direct loads (0.25fm)

IS: 1905 checks bending compression and tensile stresses independently against

permissible values. The permissible values for bending compression are obtained first by

increasing the basic compressive stress by 25% and then reducing it for eccentric loading

causing flexure. The code provides permissible loads for three eccentricity values: (a) e<

t/24, (b) t/24<e<t/6, (c) t/6<e. An applied moment can be converted into equivalent

eccentricity.

1.4.3 Shear

Masonry load bearing walls also act as shear walls to resist in-plane lateral loads due to

wind or seismic forces. The lateral load carrying capacity of shear wall structures mainly

depends on the in-plane resistances of the shear walls because the in-plane stiffness of a

shear wall is far greater than its out-of plane stiffness. Three modes of shear failure in

unreinforced masonry are possible:

1. 1. Diagonal tension cracks form through the mortar and masonry units.

2. 2. Sliding occurs along a straight crack at horizontal bed joints.

3. 3. Stepped cracks form, alternating from head joint to bed joint.

The ACI code recognizes these modes of failure and addresses them while specifying

permissible shear stresses. For prevention of diagonal cracks, in-plane shear stress should

not exceed 0.125 fm . For sliding failure, the allowable shear stress is based on a Mohr-

Coulomb type failure criterion ( η=c′+ζdtanθ ) and to resist failure due to stepped cracks,

different values of permissible shear stress are given for various bond pattern of masonry.

The IS: 1905 code only takes care of sliding failure by specifying that the permissible

shear stress fs = 0.1 + fd/6, which is a Mohr-Coulomb type failure criterion, where fd is

compressive stress due to dead loads in N/mm2.

1.4.2 Strength Design or Limit State Design


In ACI code, the nominal axial strength is based on compressive strength of masonry

modified for unavoidable minimum eccentricity and slenderness ratio, in addition to the

strength reduction factor. The expression for effect of slenderness is the same as in

allowable stress design.

Eurocode 6 also considers the effect of slenderness and eccentricity by using capacity

reduction factor. However, this capacity reduction factor is based on eccentricity not only

at the ends of member but also at middle one-fifth; wherever the moment may be

maximum.


In all the codes, the two failure modes of wall considered are parallel and perpendicular to

bed joints. The codes require the section to be checked by calculating axial and flexural

strength.



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1.4.2.3 Shear

For ACI code considers the previously discussed three modes of failure in evaluating the

nominal shear strength of masonry. Similarly IBC 2000 also considers those factors for

determining nominal shear strength of masonry and differs only in magnitude from the

ACI code. Eurocode 6 only considers a sliding mode of shear failure and prescribes an

equation of Mohr-Coulomb type (Fv = 0.1 +0.4ζd).

1.5 COMPARISON OF DESIGN CONCEPTS FOR REINFORCED MASONRY

Reinforced masonry is a construction system where steel reinforcement in the form of

reinforcing bars or mesh is embedded in the mortar or placed in the holes and filled with

concrete or grout. By reinforcing the masonry with steel reinforcement, the resistance to

seismic loads and energy dissipation capacity can be improved significantly.

1.5.1 Allowable Stress Design

Only the ACI code contains provisions on allowable stress design for reinforced masonry.


In ACI code, the allowable axial compressive load (Pa) shall not exceed (0.25fmAn+0.65

AstFs) R, which is obtained by adding the contribution of masonry and reinforcement. The

contribution of longitudinal steel is given by the term 0.65AstFs. The coefficient of 0.65

was determined from tests of reinforced masonry columns. The coefficient of 0.25

provides a factor of safety of about 4 against the crushing of masonry. Strength is further

modified for slenderness effects by the factor R, which is the same as for unreinforced

masonry.


For combined axial compression and flexure in reinforced masonry, the unity formula for

interaction is not used in designing masonry members. The unity formula is suitable for

unreinforced masonry but becomes very conservative for reinforced masonry. For

reinforced masonry emphasis has been to compute nonlinear interaction diagram taking the

effect of reinforcement and compression behavior of masonry into account. The axial load-

bending moment interaction diagram is developed using equations and assumptions very

similar to those used in analysis and design of reinforced concrete members.

1.5.1.3 Shear

When reinforcement is added to masonry, the shear resistance of masonry is increased.

Shear reinforcement is effective in providing resistance only if it is designed to carry the

full shear load. According to the ACI code, the minimum shear reinforcement is given by

the following:

Av =dF

V

s

s









1.5.2 Strength Design or Limit State Design


The nominal strength of a member may be calculated using the assumptions of an

equivalent rectangular stress block as outlined in the design assumptions. Slenderness

effect on axial load carrying capacity is also taken into account except in IBC 2000. In the

New Zealand Standards, nominal axial strength of a load bearing wall is given by

0.5fmAgR‘, where R‘ is equal to [1-(h/40t) 2].


These design assumptions vary from one code to another. According to the ACI code and

IBC 2000, εmu shall be 0.0035 for clay masonry and 0.002 for concrete masonry. In wall

design for out-of-plane loads according to both the codes, the required moment due to

lateral loads, eccentricity of axial load and lateral deformation are assumed maximum at

mid-height of the wall. In certain design conditions, such as large eccentricities acting

simultaneously with small lateral loads, the design maximum moment may occur

elsewhere.

In Eurocode 6, it is mentioned that the maximum tensile strain in reinforcement should be

limited to 0.01. According to this code, no redistribution of moment is allowed with

normal ductility steel. In this case, the ratio of depth of neutral axis to the effective depth

should not be greater than 0.4. Redistribution of moments in a continuous beam should be

limited to 15% when high ductility steel is to be used.

The New Zealand Standards, which deals with only concrete masonry, specifies that εmu

shall be 0.0025 for unconfined masonry and 0.008 for confined masonry. Confinement is

provided to the masonry walls to impart ductility to them.

1.5.2.3 Shear

Shear force is assumed to be resisted by both, masonry and reinforcement.

In Eurocode 6, there is a maximum limit to the shear strength provided by masonry and

shear reinforcement together, which is given by 0.3 fmbd/γm. It is mentioned in the New

Zealand Standards that for masonry members subjected to shear and flexure together with

axial load, the shear stress provided by the masonry shall be multiplied by the factor (1 +

12 Pu/Agfm), where P is negative for tension. Resistance to sliding along a potential shear

failure plane is provided by frictional forces between the sliding surfaces. The frictional

forces are proportioned to the coefficient of friction and the total normal force acting

across the joint, which may be provided by axial force, Pu, and distributed reinforcement,

Avffy. The effective clamping force across the crack will be Avffy + Pu. Thus the dependable

shear force, Vu, which can be transmitted across the crack by shear friction, is θμf (Avffy +

Pu). During the placing of grout, if the interface has been intentionally roughened, μf equals

1.0; else μf is taken to be 0.7.

1.6. CONCLUSION ON DESIGN CONCEPT

Among the codes studied in this document, only the New Zealand Standards contains

provisions on ductility of masonry structures and confined masonry. Regarding shear, it








contains provisions on shear friction reinforcement and also considers the case when

masonry members are subjected to shear and flexure together with axial tension.

IS:1905-1987 provides a semi-empirical approach to the design of unreinforced masonry.

The masonry codes of other countries provide detailed provision for the design of

reinforced masonry members. NBC109:1994 should adopt IS :1905-1987 and should be

independent code.

REFERENCES

NBC 109:1994, Nepal National Building Code, Masonry: Unreinforced

ACI 530-02/ASCE 5-02/TMS 402-02, (2002), Building Code Requirements for

Masonry Structures, Masonry Standards Joint Committee, USA.

ACI 530-99/ASCE 5-99/TMS 402-99, (1999), Building Code Requirements for

Masonry Structures, Masonry Standards Joint Committee, USA.

BS 5628: Part 1, (1978), Code of practice for structural use of masonry, Part 1

Unreinforced masonry, British Standards Institution

Eurocode 6, (1996), Design of Masonry Structures – Part 1-1: General rules for

buildings – Rules for Reinforced and Unreinforced Masonry, European

Committee for Standardization, Brussels.

Review of Design Codes for Masonry Buildings

IITK-GSDMA-EQ10-V1.0 15

International Building Code 2000, (2000), International Code Council, Virginia,

USA.

IS:1905-1987, (1987), Indian Standard Code of Practice for Structural Use of

Unreinforced Masonry, Bureau of Indian Standards, New Delhi.

Masonry Designer’s Guide, (Third Edition), The Masonry Society.

NZS 4230 Parts 1 & 2: 1990, (1990), Code of Practice for the Design of Concrete

Masonry Structures and Commentary, Standards Association of New Zealand,

Wellington, New Zealand.

SP 20(S & T): 1991, (1991), Handbook on Masonry Design and Construction, Bureau

of Indian Standards, New Delhi.

APPENDIX: List of symbols

Ag Gross cross-sectional area of masonry

An Net cross-sectional area of masonry

As Total area of longitudinal reinforcing steel in a reinforced masonry wall, column or pilaster

Av Cross section area of shear reinforcement

Avf Area of shear friction reinforcement

a Depth of equivalent compression zone at nominal strength

b Width of section

bw Effective web width

c Distance from extreme compression fiber to neutral axis

d Distance from extreme compression fiber to centroid of tension reinforcement

dv Actual depth of masonry in direction of shear considered

Em Modulus of elasticity of masonry in compression

e Eccentricity

ea Accidental eccentricity

ehi Eccentricity resulting from horizontal loads at top or bottom of wall

ehm Eccentricity at mid-height resulting from horizontal loads


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emk Eccentricity in the middle one-fifth of the wall

ek Eccentricity due to creep

eu Eccentricity of Puf

Fa Allowable compressive stresses due to axial load only

Fb Allowable compressive stresses due to bending only

Fs Allowable tensile or compressive stress in reinforcement

Fv Allowable shear stress in masonry

fa Calculated compressive stresses due to axial load only

fb Calculated compressive stresses due to flexure only

fm Specified compressive strength of masonry

fr Mean compressive strength of mortar

fxk Characteristic flexural strength of masonry

fu Compressive strength of masonry unit

fu Compressive strength of masonry unit

fxk1 Characteristic flexural strength in plane of failure parallel to bed joints

fxk2 Characteristic flexural strength in plane of failure perpendicular to bed joints

fy Specified yield strength of steel for reinforcement

fyk Characteristic strength of steel

h Effective height of columns, walls or pilasters

h″ Dimension of confined masonry core measured perpendicular to the direction of confining

plate being considered

In Moment of inertia of net cross-sectional area of a member

L Length of a panel between supports

lc Length of compressed part of wall, ignoring any part of wall that is in tension

M Maximum moment at the section under consideration

Mcr Nominal cracking moment strength

Md Design moment

Mi Design moment at top or bottom of wall resulting from eccentricity of floor load at support

Mm Design moment within the middle one-fifth of the wall

Mn Nominal moment strength

Mu Factored moment

Nv Compressive force acting normal to shear surface

P Axial load

Pa Allowable compressive force in reinforced masonry due to axial load

Pe Euler buckling load

Pd Design axial strength

Pi Design vertical load at top or bottom of the wall

Pm Design vertical load at middle one-fifth of the wall

Pn Nominal axial strength

Pu Factored axial load

Puf Factored load from tributary floor or roof areas

Puw Factored weight of wall area tributary to wall section under consideration

Pvf Factored axial load normal to cross-section occurring with Vu, taken positive for

compression and negative for tension

R Slenderness reduction factor

s Spacing of shear reinforcement

t Thickness of wall

V Shear force

Vd Design value of applied shear load

Vm Shear strength provided by masonry

Vn Nominal shear strength

Vs Shear strength provided by reinforcement

Vu Factored shear force at section

vi Total shear stress corresponding to Vi

vm Allowable shear stress of masonry

Z Section modulus of wall

α Bending moment coefficient depending on μ, degree of fixity at edge of panels and

aspect ratio of panels

Φi,m Capacity reduction factors

θ Strength reduction factors

δu Deflection due to factored loads

εmu Maximum compressive strain in masonry

μ Orthogonal ratio of characteristic flexural strengths of masonry, fxk1/fxk2

μf Coefficient of friction

γf Partial safety factor for loads

γm Partial safety factor for materials

γs Partial safety factor for steel

θ Angle of shear reinforcement to the axis of the member

ζd Permanent vertical stress on wall

ωu Factored out-of-plane uniformly distributed load

θ∞ Final creep coefficient

NEPAL NATIONAL BUILDING CODE

NBC 114:1994

CONSTRUCTION SAFETY


personnel in building and civil construction works. The provision in this standard are the

minimum requirements that are to be adopted during building and other civil construction or

demolition work.

This standard covers provisions for the health and safety of workers in building construction and

demolition work, planning for fire protection and any use of special materials such as chemicals


In the code, in terminology, definitions are given which can arranged in alphabetical manner.

In material handling, it is explained about material storage with safety.

In the code, exact number of requirement should be provided not in tentative or just inadequate

number for example First aid facility including an adequate number of stretchers shall be

maintained at site during execution of all types of construction and demolition works.

For the fire fighting equipment also, the number of pieces should be maintained in the code, but

not in general terms as ―adequate number‖ of fire fighting equipment .

In the code, the safety measurements are given for site preparation, Earthworks in Excavations,

construction of foundations, construction of walls, construction of roofs, electrical works,

temporary works, demolition of structures, use of explosives, labour welfare. It is maintained that

―appropriate and adequate‖ precaution or measures shall be taken maintained in the code but it

should be maintained in detailed with exact explanation.

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NNBC 108: 1994

SITE CONSIDERATION FOR SEISMIC HAZARDS

This document sets out some of the factors to be considered during site selection for buildings in

order to minimize the risks to the buildings from both primary and secondary seismic hazards.

It also outlines the fundamental requirements for site investigation for the foundation design of

buildings.

Site consideration has been considered with considering the potential of fault rupture hazard,

liquefaction, landslides and slope instability basic general concept.

Necessary mitigation measures should be taken to minimize the potential risk.

For the site investigation basic questions are given to address:

- Is there any danger of inherent natural susceptibility of the land to the process of sliding and

erosion?

- Will the construction adversely affect the existing conditions and trigger landslide, erosion,

land subsidence, pore pressure generation due to blockage of or otherwise the sub-surface flow

of water; will the construction adversely affect the water table?

- What will be the extent of settlement of the building?

- Is the sub-surface capable of taking the load due to the proposed construction?

- Is there any other natural/geological process likely to threaten the integrity of the building?

- What are the possible engineering solution for ensuring stability of the building foundation in

view of the identified condition?

Answering these questions will make necessity of additional site investigation including

subsurface exploration, in-situ and laboratory testing, geophysical surveys and testing, probing etc.

Extent of site exploration depends upon the geological and geomorphological nature of the

terrain, and on the importance of the building.

Depth of exploration is based on the geological conditions at the site e.g. the depth and type of

subsurface soil, depth of weathering, the depth of ground water fluctuation, the depth of frost

action etc.

For the analysis of liquefaction susceptibility, the actual requirement of the depth of exploration

shall be mentioned.

Determination of allowable bearing pressure and foundation design should be recommended as

per good engineering practice.







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NNBC 201:1994

Mandatory rules of thumb

Reinforced concrete buildings with masonry

The objective of these mandatory rules of thumb (MRT) is to achieve the appropriate earthquake

resistant design of those buildings in Nepal which are:

- not normally engineered

- constructed of fired brick or stone masonry in cement or mud mortars

- not more than two stories high if built in stone masonry in cement mortar or fired brick in mud

masonry

- not more than three storeys high if built or fired brick in a cement mortar.

Limitations

The MRT only intends to achieve minimum acceptable structural safety, though it is always

preferable to undertake specific design.

Non engineered buildings

The term non engineered buildings may be defined as describing those buildings which are

spontaneously and informally constructed in the traditional manner without intervention by

qualified engineers or architects in their design. However, they may follow a set of

recommendations derived from the observed behaviour of such buildings.

The main objective of the Mandatory Rules of MRT is to provide ready to use dimensions and

details for various structural elements for upto three storey reinforced concrete (RC), framed

ordinary residential buildings commonly built by owner builders in Nepal using brick infill walls.

Design guidelines presented in the MRT are the ordinary residential buildings with the seismic

coefficient of 0.128 (equivalent to seismic zone C ). However, if a buildings in all other respects

complied with the MRT were to be constructed in higher seismic zone, it would be expected to

have a better earthquake resistance than that of a similar non-engineered construction undertaken

solely with the advice of craftsmen.

In selection and investigation of site, it is recommended not to construct the buildings if the

proposed site is water logged, a rock falling area, a landslide prone area, a subsidence and/ fill

area, a river bed or swamp area.

As per MRT it is given that site exploration shall be carried out by test pit two as minimum with

the depth of 2m. No exploration shall be required if the site is on rock or fluvial terraces with

boulder beds.

METHOD OFANALYSIS

Most national codes recognize that structures with simple and regular geometry perform well during

earthquakes, and unsymmetrical placement of masonry infill walls may introduce irregularities into them.

These codes permit static analysis methods for regular short buildings located in regions of low seismicity.


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NBC -201 adopts analysis procedure in which axial forces in the frame members are estimated by assuming

a pin-jointed frame and representing masonry infill by compression diagonal struts. A method of

distributing the lateral shear force on various masonry infill walls in a story is specified in the code, which

depends upon the seismic base shear on the frame and cross-sectional and material properties of masonry

infill and RC frame members.

The masonry infill wall in such structures are intended to resist seismic loads elastically in

moderate or severe earthquakes. However, in very large earthquakes, the infill walls could be

severely damaged. For such an event, steel is provided in the walls to reduce the risk to occupants

of the building from the uncontrolled collapse of the walls under shear loads. Seismic loads will

have to be resisted mostly by frame alone. Frame has been designed to resist the gravity loads and

has been for ductility,

EMPIRICAL FORMULAE FOR NATURAL PERIOD

Several codes—IS-1893 (2002); NBC-105(1994); Algerian code 1988; suggest using an empirical formula

to calculate the natural period of masonry infill wall with RC frame structure Ta.

d

hTa 09.0

Where h is the height of the building and d is the base dimension of building at the plinth level

along the considered direction of the lateral force.

In the Nepal code NBC-201 (1995), eccentricity between center of mass and center of rigidity along each

principal direction is limited to 10% of the building dimension along that direction. The above requirement

may be satisfied by adjusting thicknesses of walls.

LATERAL DISPLACEMENT AND INTER STORY DRIFT

Lateral deformations at various levels in masonry infill -RC frame buildings depend upon the distribution

of MI walls in buildings. If more walls are present at the base, lateral deformations will be less and evenly

distributed along the height of buildings. On the other hand, if more walls are present on the upper stories,

then lateral deformations will be concentrated at the bottom, where stories are lesser infilled. Lateral

deformations and interstory drift will also depend upon the ductility and damping of buildings.

A few national codes, such as Eurocode 8 (2003), NBC-105 (1994), have restricted the interstory drift

ratio for masonry infill RC frames to about 1%. These drift ratios are calculated using displacements

obtained from elastic forces, which are amplified. FEMA-306 , ATC (1999) recommends the following

inter story drift limit states for different solid panels: for brick masonry, 1.5%; for grouted concrete block

masonry, 2.0%; and for ungrouted concrete block masonry, 2.5%. However, there is a concern that these

values are too large and further experimental studies are needed to verify these limit states.

STRENGTH OF MASONRY INFILL

Effect of Openings in Masonry Infill on Strength

Nepal code NBC-201 (1994) also requires masonry infill to be modeled as diagonal struts, without

specifying their cross-sectional properties. A minimum wall thickness of half brick is allowed to be used as

infill.

Strength Associated with Out-of-Plane Collapse of Masonry Infills

According to the Nepal code NBC-201 (1994), only those walls with an opening area less than 10% of the

gross panel area are considered as resisting seismic loads.

Openings shall be outside the restricted zone and if these openings are located inside the middle two-thirds

of a panel, then they need to be strengthened by providing RC elements around them . RC tie beams at both






the top and bottom of openings along the full length and width of the wall, and vertical elements on both

sides of the opening shall be provided with longitudinal reinforcement of two bars of 8 mm diameter. Shear

reinforcement in the form of minimum 6 mm diameter bars at every 150 mm is required in the elements.

Such strengthening elements are not required for openings in a nonsignificant area.

STIFFNESS OF MASONRY INFILL

Masonry infill walls are laterally much stiffer than RC frames, and therefore, the initial stiffness of the MI-

RC frames largely depends upon the stiffness of masonry infill. Stiffness of MI-RC frames significantly

depends on the distribution of MI in the frame. Generally, the MI-RC frames with regular distribution of

masonry infill in plan as well as along height are stiffer than the irregular MI-RC frames. Lateral stiffness

of MI-RC frames reduces with the presence of openings in infills; however, this issue has not been

addressed by the codes.

Eurocode 8 (2003), Nepal code NBC-201 (1994), and FEMA-306 recommend modeling the masonry infill

as equivalent diagonal struts. However, Eurocode 8 and Nepal code do not specify the width of strut.

Nepal code specifies the modulus of elasticity of masonry infill as 2,400 to 3,000 MPa for various grades of

mortar. On the other hand, FEMA-306 recommends using modulus of elasticity as 550 times the masonry

prism strength in the absence of tests. As per FEMA-306, the only masonry walls assumed to provide

stiffness are those that are in full contact with RC frames, or those that are structurally connected to RC

frames.

Code NBC 201 recommended the structural detailing for the building as specified in figure 1. Material

grade is taken M15 for the structural elements.

.

Figure 1

CONCLUSIONS

Infilled frames also tend to be substantially stronger, but less deformable, than identical bare frames. In

symmetric buildings with vertically continuous infilled frames, the increased stiffness and strength may

protect a building from damage associated with excessive lateral drift or inadequate strength. Because of its

higher stiffness, infill panels may attract significantly greater forces that may lead to premature failure of

infill, and possibly of the whole structure. Therefore, it is essential for designers to consider the effects of

infills in the design of RC buildings.



The codes restrict the amount of eccentricity between center of mass and center of rigidity to safeguard the

building components against the adverse effects of plan irregularities. National codes specify lower values

of response reduction factors for MI-RC frame buildings as compared to the buildings without MI, such

that MI frames are required to be designed for 1.15–3 times the design forces for the corresponding bare

frames. Lower value of response reduction factor is considered for MI-RC frames because of lower

ductility and a higher degree of uncertainty and seismic vulnerability associated with MI. A few codes have

specified limitations on the elastic and inelastic deformations and interstory drift ratio of MI-RC frames for

damage limitation requirements.

Few codes recommend modeling MI using equivalent diagonal struts; however, the required sectional

properties for the struts are not specified. Strength and stiffness of MI reduces with the presence of

openings. Various ways of reducing the damage in MI due to openings have been discussed.

In few codes, e.g., framing the openings using RC elements, full strength and stiffness of MI is not utilized

when out-of-plane collapse of infills takes place. A few codes specify limits on slenderness ratio (ratio of

length or height to thickness) to prevent outof- plane failure of masonry infill. Some national codes

recommend using light wire mesh and RC tie-bands along the length of walls at various locations to avoid

out-of plane collapse of MI.

In NNBC 201, it is demonstrated the examples for the building structure for maximum three storey and

span length not more than 4.5 m. It can not be used for other structure not following these parameters.

NNBC 202:1994

Load Bearing Masonry Buildings

Applicability

These mandatory rules of thumb (MRT) cover load bearing masonry buildings. They do not cover

wooden buildings, mud buildings (low strength buildings) or those constructed in adobe.

Limitations This MRT is valid (with certain limitations as to span, floor height, etc., as prescribed in Table 1.1) for :

i) Up to three-storeyed load-bearing brick (and other rectangular building units) masonry

buildings constructed in cement mortars.

ii) Up to two-storeyed load-bearing stone masonry buildings constructed in cement mortar.

iii) Up to two-storeyed load-bearing brick masonry buildings constructed in mud mortar.

However, these limitations shall not bar anyone wishing to employ qualified professionals to produce

an appropriate design. Structures falling outside these limitations will require the appropriate specific

design.

Floor Min. Wall

Thickness

(mm)

Max. Height

(m)

Max. short span of

floor

(m)

Cantilever

(m)

Load-Bearing Brick

Masonry in Cement Mortar 2nd 230 2.8 3.5 1.0

1st 230 3.0 3.5 1.0

Ground 350 3.2 3.5 No

Load-Bearing Stone

Masonry in Cement

Mortar, or Load-Bearing

Brick Masonry in Mud

Mortar Load-Bearing Brick

Masonry in Mud Mortar

1st

230

3.0

3.2

No

Ground

350

3.2

3.2

No

The refers to the General Construction Aspects as Opening in walls, Masonry Bond ,





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5.6 Mortars and Concrete

5.7

5.8 Vertical Joints Between Orthogonal Walls For convenience of construction, builders prefer to make a toothed joint which is later often left hollow

and weak. To obtain full bond, it is necessary to make a sloped or stepped joint. It should be

constructed so as to obtain full bond by making the corners first to a height of 600 mm, and then

building the wall in between them. Alternatively, the toothed joint shall be made in both the walls in

lifts of about 450 mm.

5.9

5.10 Roof Band This band shall be provided at the eave-level of trussed roofs (Figure 8.2) and also below gable levels

on such floors which consist of joists and covering elements - so as to integrate them properly at their

ends and fix them into the walls.

5.11

5.12 Gable Band Masonry gable ends must have the triangular portion of masonry enclosed in a band, the horizontal

part of which will be continuous with the eave-level band on the adjacent longitudinal walls .

6

7 Vertical Reinforcement in Walls Steel bars shall be installed at the critical sections (ie., the corners of walls, junctions of walls, and

jambs of doors) right from the foundation concrete. They shall be covered with cement concrete in

cavities made around them during the masonry construction. This concrete mix should be kept to 1:2:4

by volume, or richer.

The vertical steel at openings may be stopped by embedding it into the lintel band, but the vertical

steel at the corners and junctions of walls must be taken into either the floor and roof slabs or the roof

band.

NNBC 203:1994

GUIDELINES FOR EARTHQUAKE RESISTANT BUILDING

CONSTRUCTION: LOW STRENGTH MASONRY

This document provides basic guidelines for the earthquake resistance of low- strength masonry

construction.

1. Background

The devastating earthquakes in the past have proved the vulnerability of most of the

vernacular buildings of Nepal. Enormous life and property were lost due to the collapse of

buildings which LSM as the their main load-bearing element. Earthquakes can neither be

prevented nor predicted precisely. But the large-scale destruction can be minimized by

employing seismic-resistant measures in buildings. This can be achieved by the use of

existing building materials in appropriate ways. This Guideline for Earthquake-

Resistant Building Construction : Low Strength Masonry shows the improved

techniques that can raise the level of seismic safety of low strength masonry buildings.

2. Limitation

LSM buildings required to conform to this standard shall not exceed two storeys in height

with an additional attic floor.

The guideline provides details for foundations, walls, opening in the walls, structure (post

and capitals), and roof details for low strength masonry buildings.


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The guidelins also recommend harvesting and preserving bamboo for construction, fire

resistant treatment for thach roof.

NNBC 204: 1994 GUIDELINES FOR EARTHQUAKE RESISTANT BUILDING CONSTRUCTION:

EARTHEN BUILDING

Introduction

This guideline is prepared in order to raise the seismic safety of earthen buildings. This is intended to

be implemented by the owner/builder with some assistance from technicians. This could also act as a

basic guideline for architectural design and construction detailing of Earthen Buildings (EB).

This Guideline for Earthquake-Resistant Building Construction : Earthen Buildings provides the

improved techniques that can raise the level of seismic safety of earthen buildings.

The guideline provides the details of planning, foundation , wall and roof details.

NNBC 205

MANDATORY RULES OF THUMB

REINFORCED CONCRETE BUILDINGS WITHOUT INFILL

In this NNBC 205 , structural detailed has been presented for the three storeyed building example.

This code is same as NNBC 201 REINFORCED CONCRETE BUILDINGS WITH INFILL but

without infill. Generally building contains infill wall, so we have to consider the infill also in RC

construction.



Appendix-6: NBC 110, 111, 112, 113, 114:1994

NBC-110:1994 Plain and Reinforced concrete Material

NNBC 110:1994 comprises the Indian Code IS 456-1978 Code of Practice for Plain and

Reinforced Concrete (Third Revision) amended so as to meet the conditions of Nepal. In

particular, these amendments were made to ensure compatibility with NNBC 105-94: Seismic

Design of Buildings in Nepal. The Code contains the amendments that were felt necessary to IS

456-1978 for its use in Nepal.

Most of the references in IS 456-1978 to Indian material Codes had been left unaltered and it was

stated that any subsequent revisions to IS 456-1978 will not be applicable to NNBC 110-94 until

specifically recognised and updated.

The Code mostly contains the alteration, replacement, deletion and additions to IS 456-1978

The Table 12 provided the values of partial safety factors of various combinations of loads. One

more combination DL + 0.9 WL is suggested to be added.

When considering earthquake effects, the load combination requires WL to be replaced with EL.

The amendments to IS 456-1978 are limited to Structural Design with Working Stress Method

only. No further amendment is given.

Further there is a felt need to consider for inclusion of

Limit State Method

Cantilever slab Design (slab with 3 side support)

Various types of slabs with necessary coefficients αx, αy, βx, βy and provide a table of variables.

Pre-stressed Concrete should be included

Pre-cast Structures should be made

Adequate detailing of reinforced steel should be shown in NNBC to meet Earthquake Codes.

NBC-111:1994 Steel

The Code comprises the Indian Code IS 800-1984: General Construction in Steel (Second

Revision) with amendments as set out to ensure compatibility with NBC for Seismic Design of

Buildings in Nepal. References to Indian material codes have been left unaltered until such time as

appropriate Nepal Standards are developed. Extensive use of the New Zealand Standards NZS

3404: 1977 Code for Design of Steel Structures has been made.

The Code is designated as NEPAL AMENDMENTS TO IS 800 – 1984 and mostly comprise of

replacement of terminology and references. The Code applies to general construction in steel but

excludes structures such as bridges, cranes, tanks, transmission towers and masts, and materials

less than 3 mm thick and cold-formed light gauge sections.

The Code has made provisions for Seismic Design that include parameters as Ductile Moment-

Resisting Frames and Ductile Braced Framed.

NBC-112:1994 Timber

This Code covers the general principle of design of structural timber and includes specifications,

classification of timber species and nail joint in timber construction.

The code is based on Indian Standard IS: 883-1970: Structural Timber in Building (Third revision)

and IS: 2366-1983: Nail-Jointed Timber Construction (First Revision).

The Code does not cover anti-termite timber, plywood, and timber pile foundation.

The Code could be considered as comprehensive since it contains data and information on general

characteristics of timber species as durability, basic stress, Moisture Content, sizes of Sawn

Timber, Data for Nailed Joints, bolted joints, and Glue Laminated Timber.

.

The Code has made Design Considerations which include additional requirement of capacity for

sustaining the worst combination of all loadings apart from the requirement of IS Code.

NBC-113:1994 Aluminum

The document referred to as a series of guidelines intended only for design of simple aluminum

structures. Currently use of Aluminum as a structural material in Nepal is very limited and a Code

has not been prepared. For actual design, the Codes from other countries should be referred.

The Guidelines include structural properties as Strength, Modulus of Elasticity, Creep, Thermal

Expansion and Contraction, Fatigue, Corrosion Protection, Fabrication, Welding, Mechanical

Jointing, and Heating.

The code states the designers should refer to other codes if actual design.

In general it is assumed that the Code requires updating with indication of various properties of

aluminum with appropriate formula to allow proper design of aluminum structure. The use of

Aluminum in structures other than Buildings such as aircraft engineering and lightweight thin

shell structures related to Aero dynamical aspects for design consideration should also be

included. Supplementary examples of design and drawings will be very useful.

NBC 114:1994 CONSTRUCTION SAFETY


personnel in building and civil construction works. The provisions in this code are the minimum

requirements that are to be adopted during building and other civil construction or demolition

work.

This standard covers provisions for the health and safety of workers in building construction and

demolition work, planning for fire protection and any use of special materials such as chemicals


In terminology, definitions are given which can be arranged in alphabetical manner.

In material handling, it is explained about material storage with safety.

First aid facility including an adequate number of stretchers shall be maintained at site during

execution of all types of construction and demolition works.

For the fire fighting equipment, the number of pieces should be maintained in the code, not like

adequate fire fighting equipment should be provided as maintained in the code.

In the code safety measurements are given for site preparation, Earthworks in Excavations,

construction of foundations, construction of walls, construction of roofs, electrical works,

temporary works, demolition of structures, use of explosives, labour welfare. It is

maintained appropriate and adequate precaution or measures shall be taken maintained in

the code but it should be maintained in detailed with exact explanation.

Appendix 7- Review of Fire Safety Codes

1. Recent Fire Incidents ........................................................................................................... 111

2. Reasons of Fire .................................................................................................................... 112

3. Background, Objectives and Purpose .................................................................................. 113

a. Background .......................................................................................................................... 113

b. Main Objective ..................................................................................................................... 113

c. Purpose of Fire Codes .......................................................................................................... 113

d. Compliance to the Fire Code of Nepal ................................................................................. 113

4. Methodology ........................................................................................................................ 114

a. Critical study and review ...................................................................................................... 114

b. Consultation meetings with major stakeholders ................................................................... 114

5. Fire Safety Requirements In Building Codes - An Overview ............................................. 114

6. Fire Safety Requirements In Other Sector Codes - An Overview ....................................... 116

a. Fire Safety of City fuel stations ............................................................................................ 116

7. International Trends And Practices ..................................................................................... 116

a. Existing Buildings and Structures ........................................................................................ 116

b. Unsafe Buildings .................................................................................................................. 116

c. Water Supply for Fire Fighting ............................................................................................ 117

d. Fire Fighting Shafts .............................................................................................................. 117

e. Width of Escape Stairs ......................................................................................................... 117

f. Evacuation Strategies ........................................................................................................... 118

g. Evacuation Using Lifts ......................................................................................................... 118

h. Dry Riser .............................................................................................................................. 118

i. Emergency Lighting and System ......................................................................................... 118

j. Escape Lighting .................................................................................................................... 118

k. Fire Resistance Rating .......................................................................................................... 118

l. Fire Stop ............................................................................................................................... 119

m. Means of Egress ................................................................................................................... 119

8. Comparison of Fire Safety Codes ........................................................................................ 119

9. Special Consideration .......................................................................................................... 120

a. Fire fighting in High Rise Buildings .................................................................................... 120

10. Local Regulations and Organisations .................................................................................. 120

a. Local Governance Act .......................................................................................................... 120

b. Tenth Development Plan ...................................................................................................... 120

c. Building Byelaw for Municipalities in KV, 2007 ................................................................ 121

d. Building Byelaws for High Rise Buildings .......................................................................... 121

e. Fire Fighters Voluntary Association of Nepal ..................................................................... 121

f. Firefighters volunteer Association of Nepal (FAN, www.fan.org.np) is a non-governmental

organization established in year 2000 with objectives of creating awareness among the

public about fire and drawing attention of the concerned authorities on this matter. .......... 121

11. Structural Fire Engineering ................................................................................................. 121

12. Qualifications, Experience, and Responsibilities Of Fire Protection Services .................... 122

13. Fire Protection and Prevention Act ..................................................................................... 122

Review of NNBC 207: Fire Safety Codes

Recent Fire Incidents

Fire Hazard in Nepal is one of most common features of disasters. Mostly during the dry

season in Nov – June, several fire disaster events were reported in media. According to

Judha Varuna Yantra, the oldest and only public fire-fighting unit in Kathmandu, there is

one fire incident every day.

Some of the recent events are quoted herewith:

Apr 01 09: Separate fires that spread in Tikuliya and Bishahariya villages Wednesday

afternoon have gutted at least 150 houses in Saptari district. The fire has rendered some

four dozen families homeless and destroyed property estimated to be worth NRR 12

million. Fire started about 1 pm today from a fire-hearth. It was spread quickly due to

a windy weather.

Mar 25 09: About 185 Yaks have been killed and a Yak-herd has gone missing in a

wild fire that spread in the forests of eastern mountainous district Sankhuwasabha. The

misfortune occurred when a wildfire that started from Thotanekhola a few days ago

had spread to Jumlingkharka and Aibhakhkharka. Wangduk Sherpa of Taplejung who

had gone to tend the Yaks has gone missing after the fire.

18 Mar 2009 Tuesday: The Fire at Ratna Rajya Campus in Kathmandu destroyed

documents including degree certificates. It was not clear what caused the fire.

On March 12, 2009, the Moderate Resolution Imaging Spectroradiometer (MODIS)

on NASA‘s Aqua satellite caught a glimpse of a relatively rare event: large–scale

forest fires in the Himalaya Mountains of Nepal. Places where the sensor detected

active fires are outlined in red. The numerous small fires in southern Nepal may not be

wildfires, but rather agricultural or other land-management fires. Nepal commonly

experiences some small forest fires each spring, which is the end of the dry season

there. However, conditions during the fall and winter of 2008 and 2009 were unusually

dry, and fires set by poachers to flush game may have gotten out of control.

02 March 2008. A fire that swept the Goldhap refugee camp left homeless more than

10,000 Bhutanese refugees and more than 1,300 makeshift homes were destroyed.

Four people were seriously injured in the fire, and dozens suffered minor injuries. It

was unclear what sparked the blaze.

Mar 01 09: At least one person has been burnt alive and over 200 houses gutted by fire

in various parts of the country on Saturday. Sukraraj Yoktangden of Subhang VDC in

Panchthar died when he got trapped in a raging fire in Salleri forest as he was

returning home from work. The fire that started three days ago has still not come in

control. In another incident, five people have been reportedly killed in fire in Myagdi.

The names of the deceased and the extent of damage are not known. The fire started

from a house at 8 pm. Some 200 houses belonging to 76 families of Mahuwa Tole in

Saptari‘s Chhinnamasta VDC were gutted and property worth Rs 15 million damaged

when the fire spread from the house of a local, Laxmi Raut, Saturday morning. With

the advent of the dry season coupled by the prolonged dry spell, incidents of fire have

been frequent in the recent days. An entire village in Kapilvastu with about 80 houses

had been reduced to a pile of ashes by fire only a week ago.

http://modis.gsfc.nasa.gov/

http://aqua.nasa.gov/

On Feb 14, 2009, at least one person was killed and six others injured when a gas-

operated passenger van they were traveling on caught fire at Mugling in western

Nepal Saturday morning.

On Feb 13, 2009, at least 42 houses were destroyed in a fire breakout at Sankarpur

VDC in Sarlahi district allegedly set fire by a group of people from a neighbouring

village. Every year several villages in Terai are subject to fire hazard resulting in huge

toll of life and property.

Jan 2009, Nepalganj. The recent fire of Nepal Police commercial building in

Nepalganj is another example.

April 10, 2008. At least 522 families on Tuesday rendered homeless when 1,169

houses caught fire in four wards of the Belhi Chapena Village Development

Committee (VDC) in Saptari district with an estimated property loss worth NRS. 30

million.

Dec 9, 2002 Sunday evening. Myanglung Bazar, the district headquarters of Tehrathum

District, was engulfed with fire. About 300 families were rendered homeless and

property worth NRs 2 billion reduced to a cinder, after a blazing fire gutted down at

least 80 houses and several government offices.

Reasons of Fire

Various fire incidents observed mentioned above are clearly indicated the reasons of Fire.

Some of the important reasons are as follows:

Windy weather and dry season induced fire which is aggravated by:

o lack of proper planning,

o inadequate fire reserve between adjacent houses

o houses made of inflammable materials as thatch roof, bamboo partition

Relatively rare event: large–scale forest fires, wild Fire in forests

Blackout induced fire that caught due to negligence of house owner

Blackout induced Fire that caught due to accident with burning candles, incense and oil

lamp burning

Fire was aggravated since the access for Fire Fighting Vehicle was found blocked with

parking of vehicles, motorbikes, street vendors

Accidental sparks from carelessly thrown cigarette butts

Electrical short circuit

Lack of safety measures in handling inflammable fuel

Lack of Safety code on use of Gas Cylinder

Fire induced by criminal activities

Unknown Reasons

Fire-fighting preparedness is not a priority for the government compared to

earthquakes

Fire Vulnerability of existing building stock is not known and not regulated

Unsafe Buildings were not identified

Fire safety of Gas Depots, Fuel Depots and stations, and Industries are not considered.

Background, Objectives and Purpose

Background

According to the National Census 2001, about 14 % of the total population of Nepal lives

in urban areas, and this figure is expected to reach 24 % in next ten years. Besides 58

municipalities, there are 132 towns in Nepal among which, many towns are likely to be

transformed into municipalities. Due to various services, facilities and opportunities in

cities, the rate of migration from rural to urban areas in Nepal has sharply increased

because of which the existing, limited social and physical infrastructures in cities are under

added pressure. The study review and comments relating to NNBC 107 Fire Safety were

undertaken in very short duration and was not comprehensive as it should be due to the

time limitation.

Main Objective

The main objectives of fire safety design of buildings should be:

Assurance of life safety, protection of property and continuity of operations or

functioning

Building awareness among the designers for recognition of the type of danger posed by

each component of building and allows him to incorporate effective counter-measures,

and

To confine a hostile fire to a room or area of its origin.

Purpose of Fire Codes

In developed countries, the Fire Codes are made to provide minimum design regulations to

safeguard life, health, property, public welfare from fire hazard and to minimize injuries by

regulating and controlling the building permit process, design, construction, quality of

materials, use and occupancy, location and maintenance of all buildings and structures

within the jurisdiction and certain equipment specifically regulated herein.

Likewise, various kinds of new materials as roofing, walls, doors and false ceiling, wall

panels and other interior finishing materials are being increasingly used which are based on

inflammable materials as plastics. This has brought new fire and life safety challenges.

Compliance to the Fire Code of Nepal

The Fire Safety Code of Nepal (NNBC 107) was introduced in 1994 but not much

experience has been gained from this code since the code has hardly been practiced and

none of the building permits issued so far was subject to the compliance of Fire Safety

Code. These codes were not been integrated into the Building Permit procedures followed

by the Municipalities.

This Report has been prepared keeping in view the objectives, terms of reference and

methodology to be adopted, as laid down in the Inception Report (December 31, 2008).

Methodology

For preparation of this report on Fire Code, the following methodology was followed:

Critical study and review

Critical study and review of the provisions relating to:

Fire safety and fire protection in Nepal National Building Code (NNBC). The report

contains comments on the existing deficiencies/inadequacies in the document and

compared with the International Codes as National Building Code of India, International

Fire Code, International Building Code and Ontario Building Code.

The Urban Development Byelaws of Kathmandu Valley Town Development Committee

2007,

Local Self Governance Act of Nepal, 1996 and Regulations 1997.

Consultation meetings with major stakeholders

Consultation meetings with major stakeholders as DUDBC, ERRRP/UNDP, KMC, LSMC,

SCAEF, NEA, SEANEP, NSET, SEEN, SOPHEN, SOMEN, CAN, FCAN, FNCCI/CCI,

Chief Fire Officers, Water and Sanitation Authority, Licensed Designers of Municipalities

and other Civil Societies.

Feb 5, 2009 ERRRP/UNDP: Present: SEANEP, SEEN, FCAN, NSET, NEC, SCAEF,

IOE, KathEC

Feb 9, 2009 LSMC EQ Safety Section: Licensed Designers

Consultation with secondary stakeholders as Department of Forest, Contractors‘

Association, was not carried out due to time limitations

Fire Safety Requirements In Building Codes - An Overview

Those responsible for Building Codes formulation recognize the need for a modern and

up-to-date Fire Code addressing conditions hazardous to life and property from:

Fire, explosion, use of hazardous materials, and

Change in occupancies of buildings and premises.

The Fire Safety Code of Nepal National Building Code (NBC 107) has made certain

limited provisional recommendation on Fire Safety and covers ordinary buildings. It deals

only with the minimum requirements of:

Fire Places

Fire Extinguishers

Storage of Water for Fire Extinguishing

Need for demarcation of fire zones

General Requirements for Provision of:

o Proper Access

o Wide Doors

o Fire Escape Ways –Exit Doors, Fire Escapes for buildings with 5 storeys and

higher, Fire Stairs

o Open Space

o Access to a Building should be 4m wide to facilitate unconstrained movement of

Fire engine

o Lightning Arresters/Conductors.

The need for application of higher levels of fire

safety in the designs by following other relevant

[international] reference, Standards or Codes is

strongly cited.

The Indian Standards have developed a series of

Fire related codes which are listed in the Box.

IS 1642-Materials and Construction has provided Specification of materials, structural

components, and construction type based on the Fire Resistance Grading ranging from

Type 1 (6 hrs) to Type 5(½ hrs). The Indian Codes further specified the requirements for

consideration of fire hazard form exposure to fire, personal hazard, specific structures

related as Chimneys, flues, hearths etc., electrical installation. Non-electrical installations,

fire fighting equipment, and Fire proof doors.

The British Codes (BS 476-Fire Tests on Buildings and Structures) have also specified the

methods for Fire Tests on buildings and structures.

The International Fire Code (IFC) published by International Code Council is much more

intensive and cover wide range of aspects which are not included in Indian Fire Code and

NNBC. The structural outline of the IFC is listed in Table 1. The major specific features

not covered by IS and NNBC are as follows:

Administration

Emergency Planning and Preparedness

Fire Service Features

Building Service Features

Emergency access gates

Tents, Canopy, membrane structures

Fire Safety during Construction and Demolition

No Parking Fire Lane Sign Specifications

The design of important buildings, especially for high rise and special buildings has

become a complex process that requires integrating many skills, products and techniques

into its system. An intelligent building design is required to cater to various potential

emergency situations. NNBC 107 requires to be updated to the level of international code

and needs to address the pragmatic conditions existing in the downtown area and new

built up areas.

List of Indian Fire Codes

IS 1641-Fire Grading

IS 1642-Materials and Construction

IS 1643-Exposure Hazard

IS 1644-Personal Hazard

IS 1645-Chimneys, Flues, Fluepipes, Hearths

IS 1646-Electrical Installation

IS 1647-Non-electrical installations

IS 1648-Fire Fighting Equipment, Fire Proof

Doors

IS 1256-Height condition for separating walls

Fire Safety Requirements In Other Sector Codes - An Overview

Fire Safety of City fuel stations

Basic safety norms to deal with possible fires in petrol pumps across the country are dealt

by Nepal Oil Corporation (NOC). The major issue is the capability to implement these

norms. Some of the problems encountered in Safety of Fuel stations are:

A number of Fuel Stations do not adhere to the norms, risking a major fire mishap at

any time

Safety monitoring system and preparedness for any disaster are not existent;

Mechanism for regular inspection of compliance to the safety requirements are not

existent;

Knowledge and Training on ways to use the fire fighting equipment is not adequate;

The NOC norms require that a petrol pump must keep at least two fire extinguishers, four

dry, sand-filled buckets, a spade, a fire-axe, and safety gear like fire-proof clothing, and

masks.

According to the NOC, there are 74 petrol pumps in Kathmandu, 19 in Lalitpur and 14 in

Bhaktapur.

Fire Safety of Gas (cylinder) depots

The Fire code is silent about the fire safety of gas (cylinder) depots..

International Trends And Practices

Existing Buildings and Structures

The provisions of the Building Construction and Safety Code are applicable to ―existing

buildings‖ where any one of the following conditions applies:

i) Any of the use or occupancy classification occurs

ii) A repair, renovation, modification, reconstruction, or addition is made

iii) The building or structure is relocated

iv) The building is considered as unsafe building or a fire hazard

v) Use or Occupancy is changed.

Unsafe Buildings

As per NFPA 5000, ―all buildings that are, or that hereafter become as follows shall be

considered unsafe:

Structurally unsafe

Insanitary

Deficient in means of egress

A hazard from fire or natural or man-made threats

Dangerous to human life or public welfare by reasons of illegal or improper use,

occupancy or maintenance

Non compliance with the provisions of the applicable Codes

Significantly damaged by fire or explosion or other natural or manmade cause

Incomplete buildings for which building permits have expired

The falling away, hanging loose; or loosening of any sidings; block or other building

material; structural member, appurtenance, or part thereof of a building; or the

deterioration of the structure or structural parts of the building, a partially destroyed

building, or any part of a building when caused by deterioration or overstressing.

The existence of unsanitary conditions by reason of inadequate or malfunctioning

sanitary facilities or waste disposal systems.

Water Supply for Fire Fighting

Water requirement for fire fighting is a big concern. The city water networks generally

include fire hydrants at certain locations. But of late years, the fire hydrant systems are

more in disarray and the emergency supply of water is in jeopardy. The attack on World

Trade Center has raised serious question on the amount of water required for fighting fires

effectively in high-rise buildings.

Fire Fighting Shafts

(i) As per UK Building Regulations, buildings with a floor at more than 18m above fire

service vehicle access level, or with a basement at more than 10m below fire service

vehicle access level, should be provided with fire fighting shafts containing fire

fighting lifts, fire fighting stairs and fire fighting lobbies which are combined in a

protected shaft known as the fire fighting shafts. Again, buildings with two or more

basement storeys each exceeding 900m2 in area, should be provided with fire fighting

shafts, which need not include fire-fighting lifts.

(ii) Currently, several classes of buildings (industrial, storage, and commercial buildings)

less than 18m in height are also required to have a fire-fighting shaft.

(iii) An event tree analysis which was developed showed that the probability of fire spread

and casualties varies between building categories, and that other classes of building,

such as multi-storey public entertainment premises, have high rates of fire spread and

will benefit from the provision of fire fighting shafts.

Width of Escape Stairs

As per UK Building Regulations 2000 Approved Document B, FIRE SAFETY, the width

of escape stairs has been regulated as below:

(i) Stairs with a rise of more than 30m should not be wider than 1400mm unless provided

with a central hand rail

(ii) Stairs wider than 1800mm should be provided with a central handrail.

(iii) Provision of a central hand rail for wider stairs was found necessary for safe

evacuation especially for tall buildings to avoid possible jostling, collision etc. as well

as the tendency for people to stay within reach of a hand rail, especially during

prolonged descent.

Evacuation Strategies

Ensuring life safety is the most essential aspect of Building Codes. High rise and multi

storey assembly buildings pose particular challenges due to the large number of occupants

and large vertical travel distances. Traditionally the means of escape strategy mostly is

based on the principle of single stage evacuation. To achieve this, buildings are designed

with stairways of sufficient width to enable all the occupants to evacuate simultaneously.

In high-rise buildings with large number of occupants it has been found that single-phase

evacuation is a time consuming process and is impracticable. This has led to a system of

evacuation known as phased evacuation in which the building is evacuated in different

phases in the event of fire. This method is today recognized as the best method for

evacuation in high-rise buildings.

Evacuation Using Lifts

In Nepal, most of general lifts are not used during a fire. Since the lifts themselves are not

fire resistant and succumb to smoke and fire hazard. The introduction of fire fighting lifts

had not been provided.

In UK and Hong Kong, fire fighters as well as disabled people use fire fighting lifts in tall

buildings. However, there is a much wider potential use for fire protected lifts in ordinary

buildings for general evacuation purposes.

This method is particularly useful in super high-rise structures where the large vertical

travel distances result in a number of significant problems like possible increased exposure

to smoke and fire, increased fatigue during evacuation and difficulty in safe evacuation of

injured, infants, aged or disabled occupants.

Dry Riser

An arrangement for fire fighting within the building by means of vertical rising mains not

less than 100 mm internal diameter with landing valves on each floor/landing which is

normally dry but is capable of being charged with water usually by pumping from fire

services appliances.

Emergency Lighting and System

Emergency Lighting is provided for use when the supply to the normal lighting fails with

power being supplied from a standby power source.

Escape Lighting

That part of emergency lighting which is provided to ensure that the escape route is

illuminated at all material times (for example, at all times when persons are on the

premises), or at times the main lighting is not available, either for the whole building or the

escape routes.

Fire Resistance Rating

The time that a material or construction will withstand the standard fire exposure as

determined by fire test done in accordance with the standard methods of fire tests of

material/structures.

Fire Stop

A fire resistant material, or construction having a fire resistance rating of not less than the

separating elements, installed in concealed spaces or between structural elements of a

building to prevent the spread/ propagation of fire and smoke through walls, ceilings and

the like as per the laid down criteria.

Means of Egress

A continuous and unobstructed way of travel from any point in a building or structure to a

place of comparative safety

Comparison of Fire Safety Codes

Basically three codes are taken into consideration – NNBC, IS Code, and IFC. The NNBC

has made a brief provision of requirement of access, doors, and appliance whereas Indian

Code is much elaborated and includes Fire Grading, material classification, and utilities as

electrical installations. The IFC is very comprehensive and starts with the administration of

Fire Code, Emergency Planning, Fire services, Protection systems, means of egress, fire

safety during construction, protected parking for fire engines during fire events. The Euro

Code is specifically focused on structural fire safety and the features included in IFC.

NNBC 107 IS Code International Fire Code

0 Foreword IS 1641- Fire Grading 0010 Adoption.

1 Scope IS 1642: Materials and

Construction

Chapter 1 - Administration.

2 Interpretation IS 1643- Exposure Hazard Chapter 2 - Definitions.

2.1 General IS 1644 - Personal Hazard Chapter 3 - General

precautions against fire.

2.2 Terminology IS 1645 -Chimneys, Flues,

Fluepipes, Hearths

Chapter 4 - Emergency

planning and preparedness.

3 Types of

Construction and

Appliances

IS 1646 -Electrical

Installation

Chapter 5 - Fire Service

Features.

3.1 Fire Places IS 1647 - Non-electrical

installations

Chapter 6 - Building services

and systems.

3.2 Fire Extinguishers IS 1648 - Fire Fighting

Equipment, Fire Proof Doors

Chapter 9 - Fire protection

systems.

4 Fire Zones BS 476 - Fire Tests on

Buildings and Structures

Chapter 10 - Means of

egress.

5 General

Requirements

Chapter 14 - Fire safety

during construction and

demolition.

5.1 Provision of a

Proper Access

Chapter 24 - Tents, canopies

and other membrane

structures.

5.2 Provision of Wide

Doors

Chapter 33 - Explosives and

fireworks.

NNBC 107 IS Code International Fire Code

5.3 Provision of Fire

Escape Ways

APPENDIX C - Fire

Hydrant locations and

distribution.

5.4 Provision of Open

Space

APPENDIX H - Emergency

access gates and barriers.

6 Exit Requirements Exhibit A - Fire hydrant

specifications.

6.1 General

Requirements

Exhibit B. - Standard fence

and hydrant locations.

6.2 Number of Exits Exhibit #1 (C) No Parking

Fire Lane Sign

Specifications

6.2.1 Stairs

6.2.2 Fire Escapes

6.2.3 Exit Doors

7 Access to a

Building

8 Lightning

Arresters/Conducto

rs

Special Consideration

Fire fighting in High Rise Buildings

When a fire gets out of control in a skyscraper it tests fire fighters to their limits.

Predicting how a fire is behaving high up in a building is almost impossible. The fire

fighters who entered the Twin Towers on 11 September 2001 and came out live have

advocated for new system of fire protection which is called Fire grid, which keeps the fire

limited to a small area where it was generated and do not allow to spread to other areas.

Local Regulations and Organisations

Local Governance Act

The LOCAL SELF-GOVERNANCE ACT, 2055 (1999), which describes the basic

mandate of the local governments as VDC, Municipalities and DDC, has made a very

brief provision for operating and managing Fire Brigade in their area of jurisdiction. No

further provisions with regard to Fire Safety and Fire Protection are made.

Tenth Development Plan

The Tenth Plan Annex 21.1 has very briefly included a program to implement the Building

Codes Act, 1998 after making necessary amendments subsequent to the incorporation of

international norms in the areas of natural disaster including fire, flood, and landslide to

put the building construction technologies in order (Building Construction). This provision

of the Tenth Plan was dropped out in the Three Year Interim Plan without much

achievements being made.

Building Byelaw for Municipalities in KV, 2007

The Building Bylaw in general has made mandatory provisions for Building Construction

within Kathmandu Valley including municipalities and VDC emerging to towns. Apart

from the land use zoning and provisions for building construction, the bylaw also has given

guidelines in relation to access, construction along the access, conservation areas, electrical

installation regulation, and installation of Fueling stations, Cinema Halls, Housing and

Real State. The bylaws have not made any considerations in respect to disaster mitigation,

fire safety and protection, traffic management, epidemics, etc. Similarly, the Building

Bylaws do not provide guidelines for urban waste management as solid waste, waste water,

air pollution, noise pollution, and environmental protection as nature preservation.

Building Byelaws for High Rise Buildings

In May 2007, DUDBC prepared the recommendations for preparing the Building Byelaws

for High Rise Buildings in Nepal. The study recommended limiting the settlement

coverage at 40% of land and population density to be limited to 300 persons per hectare.

The Building safety and Building Fire Safety were limited to the provision of NNBC 107.

This would call for more careful consideration for updating of NNBC and adopt strong

approach for implementation of NNBC through inclusion in Building Byelaws and

Building Permit Process. The recommendation has given high priority on the provision of

water supply for fire fighting. The recommendations for Fire protection for Hise Rise

Buildings are reprinted in Appendix –A.

Fire Fighters Voluntary Association of Nepal

Firefighters volunteer Association of Nepal (FAN, www.fan.org.np) is a non-governmental

organization established in year 2000 with objectives of creating awareness among the

public about fire and drawing attention of the concerned authorities on this matter.

Structural Fire Engineering

Fire Protection Engineering comprises active and passive ways of providing satisfactory

protection level to buildings and/or its contents from fires. Active fire protection for

buildings includes fire detection and alarm systems, sprinkler, and other automatic fire

fighting systems.

Passive fire protection deals with the design of a building for adequate load bearing

resistance and for limiting fire spread under fire conditions. Structural Fire Engineering is

generally categorized in this discipline.

The structural fire resistance must be demonstrated that the structure will retain adequate

strength and stability for the required fire resistance period by considering individual

elements or a more complete assembly. The assessment may be made using prescriptive

methods or more advanced calculations either, to determine thicknesses of applied

protection or to demonstrate that some or all structural elements do not require protection.

Structural connections may require special consideration. Because each unit is generally

treated as a separate compartment, it is possible to examine the effects of localised heating

on the structure; significant savings on the cost of fire protection can thus be achieved. It is

important to consider the effect of local deformations on compartment boundaries, such as

the dividing walls between adjacent units, to ensure that they are able to maintain their

function.

The fire safety measures of buildings must satisfy the fire safety objectives specified by

codes and standards, property owners, designers, insurance bodies and approvals

authorities.

Structural Fire Engineering deals with specific aspects of passive fire protection in terms of

analysing the thermal effects of fires on buildings and designing structural members for

adequate load bearing resistance, i.e. the structural fire resistance. SFE allows fire

protection measures to be integrated into structural design. If SFE could be applied in the

design process from the very beginning of a building project, it can bring significant

benefits to the project.

Qualifications, Experience, and Responsibilities Of Fire Protection Services

A specific reference in the Codes shall be made to define the minimum qualification, skill

and responsibility of the Fire Protection services for operating the Fire Safety and

Protection operations.

Fire Protection and Prevention Act

An outline of a sample of Fire Protection and Prevention Act may include following

aspects:

Municipal Responsibilities (Community Fire Safety Officer, Fire Departments, Fire Chief, Fire

Co-Ordinators, Municipal By-Laws)

Rights Of Entry In Emergencies And Fire Investigations

Entry On Adjacent Lands By Firefighters, Etc.

Entry Where Fire Has Occurred Or Is Likely To Occur

Inspections (Inspection Orders, Service Of Order, Review Of Inspection Order By Fire

Marshal)

Appeal To Fire Safety Commission, Appeal To Divisional Court

Offences And Enforcement

Fire Marshal To Carry Out Inspection Order

Warrant Authorizing Entry

Recovery Of Costs

Appeal To Fire Safety Commission

Enforcement Of Order To Pay Costs

Firefighters: Employment And Labour Relations

WORKING CONDITIONS (STRIKE AND LOCK OUTS, HOURS OF WORK, BARGAINING RIGHTS,

ARBITRATION

Fire Safety Commission

Fire Marshal‘s Public Fire Safety Council

Miscellaneous (Protection From Personal Liability, Indemnification)

http://www.e-laws.gov.on.ca/html/statutes/english/elaws_statutes_97f04_e.htm#BK52

Appendix A: Fire Protection recommendation for Hise Rise Buildings

a. Fire Water Supply

Water supply in high-rise firefighting is critical. In a high-rise building there should be a

standpipe system to carry water for fire fighting operations to the upper floors. Depending

on the size of the building, there can be multiple standpipes placed strategically on all

floors usually in or near stairwells. These pipes shall be designed to give an adequate water

flow rate to maintain firefighting operations.

There are two systems of standpipes, a wet system and a dry system. In a wet system, the

building has fire pumps installed in the standpipe and is directly piped to a water supply,

usually a municipal water system. When there is a demand on the system, flow meters

detect a drop in pressure and the fire pumps start up and then supply water to the system.

In a dry system, there is no fire pump and the system is piped to a standpipe inlet on the

side of a building at the grade level. From this opening, the fire department connects to the

standpipe with an engine and pressurizes the system for fire fighting operations.

It is critical that a pre-fire plan be made at high-rise buildings so the incident commanders

and all fire fighting agencies know the location of the standpipe outlets on all floors and

the location of the standpipe supply inlets on the building. When connecting into a

standpipe of a building with an engine, the fire engine operator must not pressurize the

system until he/she is assured that the system is a dry pipe system. If the system is wet with

an internal fire pump it can be over pressured by the fire department causing pipe bursts

and water damage to many floors. At the standpipe outlet there is a shutoff for flow control

with usually a 2 -1/2‖ or 3‖ opening so that firefighting companies can attach their fittings

and hoses for fire operations.

When a fire alarm is sounded in a building the fire department response is that the first

arriving engine responds to the location or fire floor with their necessary equipment. The

second arriving engine connects to the building standpipe and secures a hydrant but does

not pressurize until directed by the incident commander.

In most situations this system works well, but there could be breakdowns in the water

supply system due to maintenance problems. When this occurs, an alternate plan needs to

be in place.

Pre-piped aerial ladders can be used as an external standpipe by replacing the nozzle with

the appropriate fitting and extended to the floor designated by the fire floor commander for

fire operations. This plan works well but is limited by the length of the ladder. There are

other ways for water supply to upper floors but that requires excessive manpower. The on-

scene commander must make these decisions.

b. Automatic fire detecting and alarm system

Buildings shall have an automatic fire detecting and alarm system. It is an arrangement of

automatic fire detectors, such as a fuse working at a given temperature, a thermostat or a

fluid filled tube or an electronic device, for detecting an outbreak of fire, and sounders and

other equipment for automatic transmission and indication of alarm signals without manual

intervention. The system also has provision for testing of circuits and, where required for

the operation of auxiliary services.

c. Automatic sprinkler system

In addition to detection mechanism the buildings shall also have a well designed automatic

water sprinkler system. It is an arrangement of piping, sprinklers and connected equipment

designed to operate automatically by the heat of fire and to discharge water upon that fire

and which may also simultaneously give automatic audible alarm.

d. Dry riser

The buildings shall also have a dry riser system which is a vertical fire water supply pipe ,

inside a building, not normally connected to a water main or an automatic stationary pump,

with an inlet or inlets at street level, through which water can be pumped by fire service

pumps to hydrant outlets or hose reels at various floors.

e. Fire exit

A way out leading to an escape route is mandatory in such buildings.

f. Provision of open space

The front entrance should have enough open space as defined by Architectural Design

Requirements (NBC 206) so that a number of people can gather and contribute in

extinguishing the fire, if any.

g. Fire separation

The buildings shall have adequate fire separation. It is the distance in metres measured

from any other building on the site, or from other site, or from the opposite side of street or

other public space to the building for the purpose of preventing the spread of fire.

h. Fire Tower

The building design shall incorporate a fire tower which is an enclosed staircase which can

only be approached from the various floors through landings or lobbies separated from

both the floor areas and the staircase by fire-resisting doors, and open to the outer air.

i. Fire wall

All exit ways like staircases and lobbies shall have fire resistance rated wall, having

protected openings, which restricts the spread of fire and extends continuously from the

foundation to at least I m above the roof.

j. Wet Riser

Buildings shall have a charged vertical water main inside a building, connected to a water

main or an automatic stationary pump and fitted with internal hydrants landing valves,

hose reels for tapping water at various floors.

In addition to the above mentioned general design requirements, for effective fire

prevention the following guidelines shall also be followed:

Construction

1. All materials of construction in load bearing elements, stairways and corridors and facades

shall be non-combustible. The internal walls of staircase shall be of brick or reinforced

concrete with a minimum of 2 hour fire rating.

2. The staircase shall be ventilated to the atmosphere at each landing and a vent at the top; the

vent openings shall be of 0.5 m‘ in the external wall and the top. If the staircase cannot be

ventilated, because of location or other reasons, a positive pressure of 50 Pa shall be

maintained inside. The mechanism for pressurizing the staircase shall operate automatically

with the fire alarm. The roof of the shaft shall be I m above the surrounding roof. Glazing or

glass bricks shall not be used in the staircase.

Lifts

1. Walls of lift enclosures shall have a fire rating of 2 h; lift shafts shall have a vent at the top of

area not less than 0.2 m2.

2. Lift motor room shall be located preferably on top of the shaft and separated from the shaft by

the floor of the room.

3. Landing doors in lift enclosures shall have a fire resistance of not less than half an hour.

4. Lift car door shall have a fire resistance ratting of 1 h.

5. For buildings above 15m in height, collapsible gates shall not be permitted for lifts and shall

have solid doors with fire resistance of at least I h

6. If the lift shaft and lobby is in the core of the building, a positive pressure between 25 and 30

Pa shall be maintained in the lobby and a positive pressure of 50 Pa shall be maintained in the

lift shaft. The mechanism for pressurization shall act automatically with the fire alarm; it shall

be possible to operate this mechanically also.

7. Exit from the lift lobby, if located in the core of the building, shall be through a self-closing

smoke stop door of half an hour Fire resistance.

8. Grounding switch(es), at ground floor level, shall be provided to enable the fire service to

ground the lifts.

9. To enable fire services personnel to reach the upper floors with the minimum delay, one or

more of the lifts shall be so designed so as to be available for the exclusive use of the firemen

in an emergency and be directly accessible to every dwelling/ rentable floor space on each

floor.

10. The lift shall have a floor area of not less than 1.4 m*. It shall have loading capacity of not less

than 545 kg (8 persons/lift) with automatic closing doors.

Basements

1. Each basement shall be separately ventilated. Vents with cross-sectional area (aggregate) not

less than 2.5 percent of the floor area .spread evenly round the perimeter of the basement shall

be provided in the form of grills or breakable stall board lights or pavement lights or by way of

shafts. Alternatively, a system of air inlets shall be provided at basement floor level and smoke

outlets at basement ceiling level. Inlets and extracts may be terminated at ground level with

stall board or pavement lights as before, but ducts to convey fresh air to the basement floor

level have to be laid. Stall board and pavement lights should be in positions easily accessible

to the fire brigade.

2. In multi-storey basements, intake ducts may serve all basement levels, but each basement and

basement compartment shall have separate smoke outlet duct or ducts.

3. In case of multiple basements mechanical extractors shall be designed to permit 30 air changes

per hour in case of fire or distress call. However, for normal operation, only 28 air changes or

any other convenient factor can be maintained.

4. If cut outs are provided from basements to the upper floors or to the atmosphere, all sides cut

out openings in the basements shall be protected by sprinkler heads at closed spacing so as to

form a water curtain in the event of a fire.

Fire Fighting Operations

In a normal response to a high-rise fire alarm three engines, one ladder truck, one rescue squad

and one battalion chief shall be assigned.

The first arriving engine responds directly to the floor below the alarm floor for investigation or

starting of fire operations. The first engine is assisted by the third arriving engine and the rescue

squad (if not assigned to other duties by the incident commander).

The ladder company responds to the floor above the search and ventilation operations. The second

arriving engine connects to the standpipe and secures a hydrant and then stands by for water flow

direction.

Depending on the incident, the battalion chief will set up command on the floor below or the

lobby of the building. If the investigating engine crew finds a working fire they will secure a

standpipe on the floor below the fire floor and ensure that an adequate water supply is available.

The fire attack crew will then lay a hose line to the fire floor and extinguish the fire.

The senior officer on the fire floor will assume command as the fire floor commander. The fire

floor commander will inform the incident commander of all the particulars of the incident and his

actions taken to mitigate the scene. The fire floor commander shall instruct the ladder team to gain

access to the floor above the fire to start ventilation procedures and check for vertical fire spread.

The rescue squad after an initial search will be used as manpower where needed. With this system

in place most high-rise fire incidents can run smoothly and efficiently. If other resources are

needed because of fire growth or evacuation problems this system will be able to expand as

needed.

Gaining Access

In high-rise buildings, if the incident is above the eighth floor the only two reasonable options to

reach the fire floor are elevators or stairways.

The preferred method of reaching the upper floors is by an elevator but only if it can be safely

used. The firefighter must take control of the elevator with a fire fighters key. This key allows

firefighters to by-pass the normal operations of the elevator and they then safely use the elevator

car. In elevator use, the incident commander can have his resources at the staging area a floor

below the fire much quicker and have a much safer and efficient fire attack. A firefighter needs to

know of the elevators limitations such as overloading, mechanical breakdowns, electrical failure

etc. The elevator is never to be used to go above the fire floor. Stairwells are to be used for this

purpose. When a stairway ascent is to be used, the incident commander must be aware of the time

and effort it takes to ascend to the fire floor. The initial fire attack team should be allowed to

ascend the stairs unencumbered so they can arrive at the fire floor reasonably refreshed to start fire

fighting operations.

If stairways are to be used, the incident commander will have to decide which stairway will be

used for fire fighting operations and which will be used for evacuation procedures. The incident

commander will have to know if the stairwells have standpipes, are they pressurized, are the fire

doors in place and is there access to the floors above the fire for evacuation and inspection of fire

spread. The following priorities should be used when selecting a stairwell for search and

evacuation procedures:

1. Use a fire tower (smoke proof tower), if available, for search and evacuation. If is the safest

stairway for evacuation because it is the least likely to be contaminated by smoke because of its

ventilated vestibule.

2. If a fire tower is not present in the building, use a pressurized stairway if one is available. If

more than on pressurized stairway is available, use the one most remote from the fire for search

and evacuation.

3. If no pressurized stairs are available, use the one most remote from the fire for search and

evacuation.

Ventilation

Ventilation of a high-rise building is extremely difficult and hazardous due to the construction of

the building and the effects of limited access of the building floors. In a fire in a low rise building

five floors or less, ventilation can be accomplished by normal fire fighting practices, such as roof

openings and window ventilation.

In a high-rise building these practices cannot be done. The fire could be ten floors below the roof

therefore roof openings would not have any effect on ventilating the fire. Windows on a fire floor

may not be attainable. Fire spread can block the firefighters access to the window for ventilation.

Ventilation through windows on a high- rise building can be extremely dangerous because of

falling glass over a wide spread area.

If a stairwell is available that is not being used for fire fighting or evacuation this can be used for

ventilation. This can be done by going to the roof access door of the stairwell, opening the door

and directing the smoke and heat into the stairwell and then up and out of the building.

Positive pressure fans work well for ventilation by pressurizing the fire floor and directing the

pressurized air out to the stairwell then up and out of the building. When this option is used two

fans is the minimum to be used. One fan is to be placed at the entry door to the fire close to the

opening so as to direct air into the fire floor. The second fan is placed behind the first fan to seal

the entry with pressurized air and to add more air to the fire floor to direct that and smoke out to

the ventilation stairwell and then up and out of the building.

Great care must be taken when using positive pressure fans in high-rise buildings. A good water

supply must be available before the fans can be put into operation. The smoke movement must be

monitored to ensure that it is exiting the building and not creating a hazard in other areas of the

building. Fire spread must also be monitored to ensure that the fans are not enhancing or moving

the fire to other compartments or floors of the building.

High-rise buildings have a large and complicated H.V.A.C. system that control air movement in

the structure. These units can be used to ventilate the fire floors. The practice should only be done

under the supervision of the building engineers or maintenance employees familiar with H.V.A.C

systems. Exhaust fans in the structure can be put in use to evacuate the fire floor or air movement

can be redirected for ventilation purposes. Good ventilating practices in a high-rise incident is a

vital aid in fire suppression and will reduce structural damage to the building.

Egress and Evacuation Requirements

Evacuation of a high-rise building in an emergency situation is a very difficult process. If the

building needs to be evacuated call for an extra alarm for evacuation purposes has to be made. The

extra alarm resources will be used to direct the building occupants down the proper stairs and to

search the building for trapped occupants.

When evacuating occupants a stairwell that is free of smoke or heat and not used for firefighting

operations should be used. The occupants should be directed away from the elevators and to the

proper stairwell for egress. Upon the arrival at the lobby or the grade floor occupants should be

directed to a safe area away from the building and firefighting operations.

If the fire or incident can be contained to one floor or area, the occupants can and should be

evacuated in place. If there is no danger in their specific area it should be suggested that they stay

in their office or apartment and wait for the incident to be mitigated. If evacuation in place is to be

used the occupants must be reassured that there is no danger and their interests are being looked

after. In theory, this in how evacuation should take place, but in practice the fire department will

arrive on the scene with people fleeing the building by whatever means they find available.

Stairwells will be clogged with people hindering firefighters trying to reach the fire scene.

Occupants will be trying to use elevators for egress and there will be a sense of panic.

The incident commander and firefighters must immediately take control and try to remove people

in a calm and orderly manner. This process will start on the grade floor and work up as firefighters

rise higher in the building. Firefighters will have a calming effect with their presence and this can

be used in evacuation and direction. There are two types of evacuation: self evacuation of the total

building and controlled selective evacuation.

Self evacuation takes on a life of its own and is a haphazard process. It is based entirely on the

decisions and actions carried out by the buildings occupants. This is the scene of most high-rise

fires that firefighters will find on arrival and they will need to step in and take control.

Controlled selective evacuation requires that the building management have input in the decision

making process and execution of the actions needed to evacuate. This should be coordinated with

the fire department. This will be found in the daytime when management is on site and if the

occupants have practiced evacuation procedures.

The first arriving firefighters will rarely see this perfect scenario. Upon arrival at the scene of a

high-rise fire, the fire department must take control of the scene as it is found and use all the

resources available to them for evacuation

General Requirements

An exit normally shall consist of either a doorway, corridor or passageway to an internal staircase,

to an external staircase, to a verandah leading to the street, to the roof of a building, or to the

street. The exit may also lead to another building in the neighbourhood. The exit should :

a) be able to allow the evacuation of all the occupants in a relatively short time;

b) meet the minimum requirements as to size;

c) be free of any obstructions and shall not provide any resistance to movement;

d) be clearly visible, preferably with proper signs.

e) be continuous and shall not intrude into private space.

Stairs

The number of stairs in any building, especially when it exceeds 500 square metres in plinth area,

shall be a minimum of two, one internal and the other an external fire escape. Additional stairs

shall be provided in proportion to any increase in the plinth area. In the case of residential

buildings, the minimum width of the stairs shall be 90 cm. For other buildings, the minimum

width shall be 1.5 m. The distance from any point in a passageway to a staircase in a building shall

not exceed 20 meters.

Fire Escapes

Every building more than five storeys high shall have a separate fire escape having a minimum

width of 75 cm. The fire escape shall have a minimum tread width of 20 cm and each riser shall be

not more than 19 cm high. The number of risers per flight shall not be more than 15. Such a fire

escape shall carry users towards an open space.

Exit Doors

Exit doors shall open to a passageway or to a corridor. They should open outwards, but without

restricting the movement of people passing outside the door. The maximum distance of such an

exit doorway from any point in a passage shall be 20 m. The exit doorway shall neither be smaller

than 90 cm in width, nor 180 cm in height.

Lightening Arrester

A lightning arrester shall be located in the highest part of every building and it shall be connected

by a conductor to an earth rod buried in the earth. The lightning arrester shall be so located that as

much as possible of the building lies inside the surface of an imaginary cone having a vertex angle

of 45 degrees and its apex at the top of the arrester.

All other provision shall be in confirmation with Nepal National Building Code (NBC 107:1994)

and National Building Code of India 1983 and Indian Standard Provisions IS:1642:1989,

IS:1643:1988, IS 1644:1988, and IS:1646:1997, for Fire Safety of Buildings.

Fire Hazard of Timber Bridges

Several of Timber Bridges along East West Highway were set into fire during conflict

time. This issue not given much attention.

Appendix-8: Review of Mandatory rules of thumb

NNBC 201:1994

Reinforced concrete buildings with masonry

Objectives

The main objective of the Mandatory Rules of MRT is to provide ready to use dimensions and

details for various structural elements for upto three storey reinforced concrete (RC), framed

ordinary residential buildings commonly built by owner builders in Nepal using brick infill walls.

The objectives of these mandatory rules of thumb (MRT) are to achieve the appropriate

earthquake resistant design of those buildings in Nepal which are:

1- Designed and constructed without professional engineers intervention (non-engineered)

- constructed of fired brick or stone masonry in cement or mud mortars

2- not more than two stories high if built in stone masonry in cement mortar or fired brick in mud

masonry

3- not more than three storeys high if built or fired brick in a cement mortar.

- Single span is less than 4.5m and Plinth Area is less than 100 m2

Limitations

The MRT only intends to achieve minimum acceptable structural safety, though it is always

preferable to undertake specific design.

Non-engineered buildings

The term non-engineered buildings may be defined as those buildings, which are spontaneously

and informally constructed in the traditional manner without intervention by qualified engineers or

architects in their design. However, they may follow a set of recommendations derived from the

observed behavior of such buildings.

Design Guidelines

The design guidelines presented in the MRT cover ordinary residential buildings with seismic

coefficient of 0.128 (equivalent to seismic zone C ). However, if the buildings in all other respects

complied with this MRT , it would be expected to have a better earthquake resistance than that of

a similar non-engineered construction undertaken solely with the advice of craftsmen.

For selection and investigation of site, it is recommended not to construct the buildings if the

proposed site is water logged, a rock falling area, a landslide prone area, a subsidence and/ fill

area, a river bed or swamp area.

As per MRT, it is given that site exploration shall be carried out by test pit two as minimum with

the depth of 2m. No exploration shall be required if the site is on rock or fluvial terraces with

boulder beds.

METHOD OF ANALYSIS

Most national codes recognize that structures with simple and regular geometry perform well during

earthquakes, and unsymmetrical placement of masonry infill walls may introduce irregularities into them.

These codes permit static analysis methods for regular buildings located in regions of low seism city.

irregularities into them. These codes permit static analysis methods for regular buildings located in regions

of low seismicity.











NBC -201 adopts analysis procedure in which axial forces in the frame members are estimated by assuming

a pin-jointed frame and representing masonry infill by compression diagonal struts. A method of

distributing the lateral shear force on various masonry infill walls in a story is specified in the code, which

depends upon the seismic base shear on the frame and cross-sectional and material properties of masonry

infill and RC frame members.

The masonry infill walls in such structures are intended to resist seismic loads elastically in

moderate or severe earthquakes. However, in very large earthquakes, the infill walls could be

severely damaged. For such an event, steel is provided in the walls to reduce the risk to occupants

of the building from the uncontrolled collapse of the walls under shear loads. Seismic loads will

have to be resisted mostly by frame alone. Frame has been designed to resist the gravity loads and

provide ductility.

EMPIRICAL FORMULAE FOR NATURAL PERIOD

Several codes—IS-1893 (2002); NBC-105(1994); Algerian code 1988; suggest using an empirical formula

to calculate the natural period of masonry infill wall with RC frame structure, Ta.

d

hTa 09.0

Where h is the height of the building and is the base dimension of building at the plinth level along

the considered direction of the lateral force.

In the Nepal code NBC-201 (1995), eccentricity between center of mass and center of rigidity along each

principal direction is limited to 10% of the building dimension along that direction. The above requirement

may be satisfied by adjusting thicknesses of walls.

LATERAL DISPLACEMENT AND INTERSTORY DRIFT

Lateral deformations at various levels in masonry infill (MI) of RC frame buildings depend upon the

distribution of MI walls in buildings. If more walls are present at the base, lateral deformations will be less

and evenly distributed along the height of buildings. On the other hand, if more walls are present on the

upper stories, then lateral deformations will be concentrated at the bottom, where stories are less infilled.

Lateral deformations and inter-story drift will also depend upon the ductility and damping of buildings.

Few national codes, such as Eurocode 8 (2003), NBC-105 (1994), have restricted the inter-story drift ratio

for masonry infill RC frames to about 1%. These drift ratios are calculated using displacements obtained

from elastic forces, which are amplified. FEMA-306, ATC (1999) recommends following inter-story drift

limit for different solid panels: for brick masonry, 1.5%; for grouted concrete block masonry, 2.0%; and for

ungrouted concrete block masonry, 2.5%. However, there is concern that these values are too large and

further experimental studies are needed to verify these limits.

STRENGTH OF MASONRY INFILL

Effect of Openings in Masonry Infill on Strength

Nepal code NBC-201 (1994) also requires masonry infill to be modeled as diagonal struts, without

specifying their cross-sectional properties. A minimum wall thickness of half brick is allowed to be used as

infill.

Strength Associated with Out-of-Plane Collapse of Masonry Infills

According to NNBC-201 (1994), only those walls with an opening area less than 10% of the gross panel

area are considered as resisting seismic loads. Openings shall be outside the restricted zone and if these

openings are located inside the middle two-thirds of a panel, then they need to be strengthened by

providing RC elements around them. RC tie beams at both the top and bottom of openings along the full

length and width of the wall, and vertical elements on both sides of the opening shall be provided with

longitudinal reinforcement of two bars of 8 mm diameter. Shear reinforcement in the form of minimum 6

mm diameter bars at every 150 mm is required in the elements. Such strengthening elements are not

required for openings in a nonsignificant area.

STIFFNESS OF MASONRY INFILL

Masonry infill walls are laterally much stiffer than RC frames, and therefore, the initial stiffness

of MI-RC frames largely depend upon the stiffness of masonry infill. Stiffness of MI-RC frames

significantly depends on the distribution of MI in the frame, generally, the MI-RC frames with regular

distribution of masonry infill in plan as well as along height are stiffer than the irregular MI-RC frames.

Lateral stiffness of MI-RC frames reduces with the presence of openings in infills; however, this issue has

not been addressed by the codes.

Eurocode 8 (2003), Nepal code NBC-201 (1994), and FEMA-306 recommend modeling of masonry infill

as equivalent diagonal struts. However, Eurocode 8 and Nepal code do not specify the width of strut.

Nepal code specifies the modulus of elasticity of masonry infill as 2,400 to 3,000 MPa for various grades of

mortar. On the other hand, FEMA-306 recommends using modulus of elasticity as 550 times the masonry

prism strength in the absence of tests. As per FEMA-306, the only masonry walls assumed to provide

stiffness are those that are in full contact with RC frames, or those that are structurally connected to RC

frames.

Code NBC 201 recommended the structural detailing for the building as specified in figure 1.

Material grade is taken M15 for the structural elements.

Figure 1

CONCLUSION

Infilled frames also tend to be substantially stronger, but less deformable, than otherwise identical bare

frames. In symmetrical buildings with vertically continuous infilled frames, the increased stiffness and

strength may protect a building from damage associated with excessive lateral drift or inadequate strength.

Because of its higher stiffness, infill panels may attract significantly greater forces that may lead to

premature failure of infill, and possibly of the whole structure. Therefore, it is essential for designers to

consider the effects of infills in the design of RC buildings.

The codes restrict the amount of eccentricity between center of mass and center of rigidity to safeguard the

building components against the adverse effects of plan irregularities. National codes specify lower values

of response reduction factors for MI-RC frame buildings as compared to the buildings without MI, such

that MI frames are required to be designed for 1.15–3 times the design forces for the corresponding bare

frames. Lower value of response reduction factor is considered for MI-RC frames because of lower

ductility and a higher degree of uncertainty and seismic vulnerability associated with MI. A few codes have

specified limitations on the elastic and inelastic deformations and Inter-story drift ratio of MI-RC frames

for damage limitation requirements.

Few codes recommend modeling MI using equivalent diagonal struts; however, the required sectional

properties for the struts are not specified. Strength and stiffness of MI reduces with the presence of

openings; Various ways of reducing the damage in MI due to openings have been discussed in few codes,

e.g., framing the openings using RC elements. Full strength and stiffness of MI is not utilized when out-of-

plane collapse of infills takes place. A few codes specify limits on slenderness ratio (ratio of length or

height to thickness) to prevent outof- plane failure of masonry infill. Some national codes recommend

using light wire mesh and RC tie-bands along the length of walls at various locations to avoid out-of plane

collapse of MI.

Since in MRT 201, the examples demonstrate the building structure for maximum three storey and span

length not more than 4.5 m and it can not be used for other structures not following these parameters.

The purpose of MRT is to allow the design and construction of selected type of buildings without

intervention of professional engineers. MRT has defited this pupose since the building permit

proes requires certification by a lcensed designer. The preparation of design (rather municipal

drawings) are so complicated that non-engineered design cannot be produced and approved by

municipality. For these reasons, MRT is recommended to be eliminated as part of the code. But

few samples of buildings could be developed with consideration of the Code requirements and

made available free of cost and without need for going through the building permit process.

MRT has allowed non-design professionals to carry the responsibility for creating site-specific

designs using MRT and compelling building inspectors to attempt to confirm these designs as

correct in the field. This means the buildings designed and constructed under MRT do not

warranty the Safety.

NNBC 202:1994 - Load Bearing Masonry Buildings

Applicability

These mandatory rules of thumb (MRT) cover load bearing masonry buildings. They do not cover

wooden buildings, mud buildings(low strength buildings) or those constructed in adobe.

Limitations As prescribed in Table 1.1, MRT is valid (with certain limitations as to span, floor height, etc.,) for:

i) Up to three-storeyed load-bearing brick (and other rectangular building units) masonry buildings

constructed in cement mortars.

ii) Up to two-storeyed load-bearing stone masonry buildings constructed in cement mortar.

iii) Up to two-storeyed load-bearing brick masonry buildings constructed in mud mortar.

However, these limitations shall not bar anyone wishing to employ qualified professionals to produce

an appropriate design. Structures falling outside these limitations will require the appropriate specific

design.

Floor Min. Wall

Thickness

(mm)

Max. Height

(m)

Max. short span of

floor

(m)

Cantilever

(m)

Load-Bearing

Brick Masonry in

Cement Mortar

2nd 230 2.8 3.5 1.0

1st 230 3.0 3.5 1.0

Ground 350 3.2 3.5 No

Load-Bearing

Stone Masonry in

Cement Mortar, or

Load-Bearing

Brick Masonry in

Mud Mortar

1st

230

3.0

3.2

No

Ground

350

3.2

3.2

No

8

9 General Construction Aspects

9.5 The general construction aspects have included Opening in walls, Masonry

Bond, reinforcment details,Vertical Joints Between Orthogonal Walls,Roof

Band, Gable Band, and Vertical Reinforcement in Walls.

NNBC 203:1994

GUIDELINES FOR EARTHQUAKE RESISTANT BUILDING

CONSTRUCTION: LOW STRENGTH MASONRY (LSM)

This document provides basic guidelines for the earthquake resistance of low- strength masonry

construction.

Background The devastating earthquakes in the past have proved the vulnerability of most of the vernacular

buildings of Nepal. Enormous life and property were lost due to the collapse of buildings which

LSM as their main load-bearing element. Earthquakes can neither be prevented nor predicted

precisely. But the large-scale destruction can be minimized by employing seismic-resistant

measures in buildings. This can be achieved by the use of existing building materials in

appropriate ways. This Guideline for Earthquake-Resistant Building Construction: Low

Strength Masonry shows the improved techniques that can raise the level of seismic safety of

low strength masonry buildings.

Limitation LSM buildings required to conform to this standard shall not exceed two storeys in height with an

additional attic floor.

The guideline provides details for foundations, walls, opening in the walls, structure (post and

capitals), and roof details for low strength masonry buildings.

The guidelines also recommend the method of harvesting and preserving bamboo for

construction, and fire resistant treatment for thatch roof.

Conclusion

MRT has made certain details of construction. In the absence of a proper design, the buildings

being constructed are not properly planned because of lack of capacity to prepare a proper plan.

The seismic resistance and fire resistance are not warranted. It would be much helpful to provide

some examples of LSM buildings designs that could be readily applicable.

NNBC 204: 1994 GUIDELINES FOR EARTHQUAKE RESISTANT BUILDING CONSTRUCTION:

EARTHEN BUILDING

Introduction

This guideline is prepared in order to raise the seismic safety of earthen buildings. This is intended to

be implemented by the owner/builder with some assistance from technicians. This could also act as a

basic guideline for architectural design and construction detailing of Earthen Buildings (EB).

This Guideline for Earthquake-Resistant Building Construction: Earthen Buildings provides the

improved techniques that can raise the level of seismic safety of earthen buildings.

The guideline provides the details of planning, foundation, wall and roof details.

The comments provided in Conclusion above applies.

Appendix 9 – Review of NNBC 206: 2003 Architectural Design Requirement.

‗Building Code‘ is basically an ‗Architectural Code‘. Whereas, ‗Building by-laws‘ is the mother

of ‗Building Code‘. Nevertheless, ‗Architectural Code‘ and hence ‗Building Code‘ now is

considered the foundation and basis of ‗Building by-laws‘.

The Building by-laws for Greater Kathmandu Valley, prepared by Kathmandu Valley Town

Development Committee and NNBC 206: 2003 Architectural Design Requirement are the basis

for the recommendation to update the Architectural Design Code.

The updated version of the existing code NNBC 206: 2003 Architectural Design Requirement, will

serve the purpose of guiding the building designers and planners to fulfill their responsibilities of

creating built environment that will be safe, healthy and beneficial to the community as a whole.

The code will not contradict the innovativeness and creativeness of the designer and the planner.

This will be the logical conclusion of the contents of the code, as it spells out the minimum

requirements in the design of buildings and its surroundings in serving the objective of the code.

Hence, ―tolerant of uncertainty‖ and ―welcomes experiments‖ character of architecture will be

maintained.

After much deliberation at different stages, the consultant did not receive any substantial criticism

or recommendation for changes in the existing document, exclusion of neighborhood planning

codes, conservation, and FAR values in the existing code, however, were spelled out.

NNBC 206 has dealt architectural elements only from safety point of view. The NNBC 206: 2003

Architectural Design Requirements have dealt certain aspect of design norms for architectural

works as listed below:

1. Staircase.

2. Exit (General Exit requirement and Exit Doors.

3. Lighting and Ventilation.

4. Requirement for the Physical disabled.

5. Glazing in Hazardous location.

6. Parapet height.

Therefore, it was aptly termed ‗Architectural Design Requirements’ rather than ‗Architectural

Code‘ as we have with ‗fire safety‘ or ‗structural‘ and many others. The clauses of the existing

code do not require any changes. What are necessary are definitely, more details in each and

additional clauses to be incorporated in the new updated code as listed below.

A building, complying all requirements of the code by itself, cannot guarantee fulfillment of the

objective of code. As the building stands in a space of multiple of such objects, certain aspects of

neighborhood planning needs to be included which are absent in the existing NNBC 206: 2003

Architectural Design Requirements. Even so, it is to be noted down that, planning code is not land

use zoning, although in some countries and places it is treated as the same way. For the purpose of

the present recommendation, elements of Zoning Regulation and Building by-laws will not form

the part of this code. Similarly, Architectural code should not be confused for an architectural

design code.

The other aspect to be mentioned is the non consideration of high rise buildings in the existing

code.

One of the important aspects for the Architectural Code is the big differences in the architectural

expression in different geographical area of the country. Certain recommendations to this aspect

will also from the part of this report. In the above context, the updated code is suggested to be the

guide in preparing the by-laws of different municipalities and VDCs.

The following recommendations based on the above with certain new elements are proposed to be

considered while updating the existing NNBC 206: 2003 Architectural Design Requirements,

considering the present context of the country.

Recommendations for updating of the existing Building Code.

A. Division of the country in three different geographical zones for formulation of

Architectural code. An alternate suggestion for division of zones is;

1. Himalayan and Inner Himalayan Zone. (Altitude. > 3,000 m)

2. Hill and Mountain Zone. (Altitude 400-3000m)

3. Terai Zone (alt >70m <400 m)

B. Define Building Categories (or Class) based on buildings materials, uses and life span.

C. Recommendation matrix.

Three different alternatives are recommended for three different geographical zones. S. No. Elements of building

and neighborhood

planning.

Particular

dimensional aspects

Additional for buildings of Public

mass assembly type. (Buildings of

community use, industrial type and

others)

1 2 3 4

1. Doors and Exists

minimum width and

height

i. Total width of the entry and exit

doors depending upon the

maximum number of users at one

time.

ii. Direction of opening.

iii. Emergency doors with signage.

2. Rooms.

(including offices,

kitchen, stores, attics

mezzanine floors,

basements etc)

i. Height.

ii. Minimum area and

proportion of

length to breadth.

i. Height.

ii. Minimum area and proportion of

length to breadth.

iii. Relation between the volume and

maximum number of users of the

space at one time.

3. Openings for light and

ventilation.

i. Provision of natural

light

ii. Minimum area of

openings for light and

ventilation.

i. Provision of natural light

ii. Minimum area of openings for

light and ventilation.

4. Steps and Stairs i. Riser and treads

ii. Total number of

steps in one flight.

iii. Width for different

type of buildings.

iv. provision of hand

rails and its height.

i. Total width of the stairs in relation

to the maximum number of users

served at one time.

ii. Provisions for physically disabled.

iii. Emergency stairs and signage.

5. Lift i. Length, breadth and

height of

compartment.

ii. Ventilation and light

i. Total number of lift units and total

capacity in the structure.

ii. Provisions in high rise buildings.

6. Parapet Height height

S. No. Elements of building

and neighborhood

planning.

Particular

dimensional aspects

Additional for buildings of Public

mass assembly type. (Buildings of

community use, industrial type and

others)

7. Corridors and

emergency exits

i. Width vs. number of

users and total

length.

ii. Light and

ventilation.

i. Width vs. number of users and total

length.

ii. Light and ventilation

iii. Emergency exits.

iv. Non smoking stairs.

8. Plinth Height from the road

level.

Height from the road level.

9. RRooooff PPiittcchh SSllooppee aanndd mmaaxxiimmuumm

ssllooppee lleennggtthh.. SSllooppee aanndd mmaaxxiimmuumm ssllooppee lleennggtthh..

10. Rain water Gutter Gutter outlets from

buildings.

Gutter outlets from buildings.

11. Access to

neighborhood.

Width of access road in

relation to its length.

Total width of access road in relation

to the accumulation of people..

12. Right of way and

building line.

Distance from the

center of the road.

Distance from the center of the road.

13. Cul-de-Sacs. Condition of inclusion. Condition of inclusion.

14. Pedestrians. Pedestrian path in

neighborhood road.

Pedestrian path in neighborhood

road.

15. Open spaces Provision of individual

and community open

space.

Provision community open space.

16. Storm drainage. Provision of drainage

and outlet.

Provision of drainage and outlet.

17. Cultural aspects. Due consideration, to the cultural sites like heritage, monument,

and spaces valued as a cultural property, be followed & as

necessary as specified in Monumental Zone bylaws or any such

regulations of specific municipalities, VDC or settlements.

18. Below ground space

i. Particular uses

ii. Height and Width of Entry and Exits

iii. Light, height and ventilation in the space.

19. VVeehhiiccllee PPaarrkkiinngg ---- Parking for Minimum number of

vehicles.

20. SSppaaccee aassssoocciiaatteedd wwiitthh

hhaazzaarrddoouuss mmaatteerriiaallss ---- Safety measures in design

D. High Rise buildings.

The above item wise recommendations will be applied to high rise buildings separately

including the separating distance between high rise structures.

Aspects of i) Light, ii) ventilation and iii) emergency exit (smokeless stairs) will be

specified for high rise buildings separately. The rest will be treated in the general

design requirement part of the code.

E. Other important aspects.

C. Ample sketches and drawings will be included interpreting the articles wherever

applicable.

Definition of different parts of building which will be mentioned in the code needs to be

clearly given in the new code.

Appendix-10: Review of NNBC – 207: 2003

(Electrical Design Requirements for Public Buildings)

Background

Electrical service is a part of the building services which turns building shell into a habitable one.

But, if the electrical equipment and wiring are improperly installed and if neglected, electricity

itself may pose hazard. Electrical code sets out rules by which everyone, by law, should adhere to

when working with electricity or installing and maintaining electrical equipment.

Electrical codes are not well developed in Nepal. Even in such circumstances, the preparation of

Electrical Design Requirements for Public Buildings, NBC 207-2003 as a part of Nepal National

Building Code, is a praiseworthy work. Codes all over the world are revised and developed

regularly. In this context, the update of Nepal National Building code is necessary and help shall

be taken from other national building codes developed by other countries. Keeping in mind that

Nepal National Building code should be understandable and easy to use for the general public,

efforts have been made to congregate information as much as possible.

General

The Electrical Design Requirements for Public Buildings, NNBC-207-2003 has covered most of

the aspects related with the Building code. But it would be easier to use the code, if following

basic points were included:

terminology,

graphical symbols,

tables, and

drawings etc,.

Secondly, instead of referring to other foreign codes, which are not easily accessible to general

public, it would be better to include the full text of the codes in NNBC as far as possible.

Thirdly, the Safety Procedures and Practices has to be included.

Proximity of the buildings from the electric lines,

Standard Voltage and its allowable deviations,

Prohibition of building construction below electric lines,

Installation of a danger board on every switch board above 230 V.

Installation of Primary First Aid method board on every sub-station.

Planning of Electrical Installations:

The code should include following basic tasks while planning and designing an electrical

installation :-

1. type of occupancy;

2. type of supply;

3. earthing;

4. load;

5. atmospheric condition;

6. degree of protection;

7. future increase of load;

8. maintenance and safety aspects;

9. energy consumption;

10. continuity of supply;

11. Energy Conservation,

12. Alternative energy sources during emergencies

13. need for radio and telecommunication interference suppression;

14. Comparison of costs of various alternative variants.

Electrical apparatus

All Electrical Apparatus shall be suitable for the services what they are intended for.

Co-ordination

i) Clients may have their own view and requirements. Hence, before starting of wiring and

installation, the collection of views from Architecture /Electrical Contractor, the local

supply Authority` along with the client would be of utmost importance.

ii) In the clause "Load Centre and Centre of Gravity of Building‖, the availability of the

power lines nearby may also be kept in view while deciding the location of the Substation.

Capacity and Size of sub-station

Tables of the area required for transformer room and substation for different capacities along with

the table of Additional area required for Generator in electric substation should be included.

As per the Indian Standard, the Requirements of Rooms shall considered following points:-

i) Rooms shall be provided with windows and independent access doors ;

ii) Rooms shall have partitions up to the ceiling with proper ventilation.

iii) Transformer floors shall have proper ventilation and where necessary louvers at lower

level and exhaust fans at higher level shall be provided at suitable locations.

iv) In order to prevent storm water entering the transformer and switch rooms through the

soak-pits, the floor level of the substation shall be at least 15cm above the highest flood

water level that may be anticipated in the locality.

v) The minimum height of the high voltage switchgear room shall be 3.6m.

Location of Switch Room

In large installations, where a substation is provided, a separate switch room shall be provided.

This shall be located as closely as possible to the electrical load centre and suitable ducts shall be

laid with minimum number of bends from the point of entry of the main supply cable to the

position of the main switchgear. The switch room shall also be placed in such a position that rising ducts may readily be provided there from to the upper floors of the building in one straight vertical

run. In larger buildings, more than one rising duct may be required and then horizontal ducts may

also be required for running cables from the switch room to the foot of each rising main. Such

cable ducts shall be reserved for the electrical services only which may, however, include medium

and low voltage installations, such as call-bell systems; telephone installations, should be suitably

segregated. Location and Requirements of distribution Panels should be mentioned in the code.

Distribution of Supply and Cabling :

In the field of building construction high rise buildings is a new development, mainly in the cities.

So, the time has come to include in NNBC the use of high voltage distribution system of supply in

the buildings.

Following clauses and points should be included: 1. All electrical apparatus should be suitable for the voltage and frequency of supply.

2. In very large industrial buildings where electricity is supplied at high voltage from the main

substation, selection of high voltage switchgear should be done under the following consideration-

voltage of supply system;

prospective short-circuit current at the point of supply;

size and layout of electrical installation;

accommodation available; and

nature of industry.

Making and breaking capacity of switchgear

Cables

Code for laying of the H.T. cables depending upon the specific requirements should be given.

Transformer

Code for selection of the maximum size of transformer used to supply a medium voltage

installation from a high voltage network should be mentioned e.g..

present load;

possible future load;

operation and maintenance cost and other system conditions; and

short-circuit making and breaking capacity of the switchgear used for controlling the

medium voltage distribution system.

Low Voltage Switchgear

Criteria for selecting the Switchgear and fuse gear in relation to the capacity of the

transformers ultimately to be connected is necessary to include.

It should be mentioned that Isolation and protection of outgoing circuits forming main

distribution system may be effected by means of circuit-breakers, or fuses or switch and

fuse units mounted on the main switchboard. The choice between alternative types of

equipment may be influenced by the following considerations-

i) In certain installations supplied with electric power from remote transformer

substations, it may be necessary to protect main circuits with circuit-breakers

operated by earth leakage trips, in order to ensure effective earth fault protection.

ii) In installations where overloading of circuits may be considered unlikely, HRC

type fuses will normally afford adequate protection for main circuits. Where means

of isolating main circuits separately is required, the fuses shall be mounted in fuse

switch or switch fuse units or with switches forming part of the switchboards. iii) It is better to mention the requirement of:

passages to all the switchboards for operation and maintenance;

providing of proper means for isolating the equipment;

sufficient additional space for anticipated future extensions.

Keeping in view the safety of people, it is necessary to mention that all electrical

installations in a room or cubicle or in an area surrounded by wall fence, access to which is

controlled by lock and key shall be considered accessible to authorized persons only.

Reception and Distribution of Main supply

1. All main switches shall be either of metal-clad enclosed pattern or of any Insulated

enclosed pattern which shall be fixed at close proximity to the point of entry of supply.

2. Safety should be in first priority while fixing the location of main board and switchboards.

Hence, following criteria are recommended to mention in the code:

a) Easy accessibility for firemen and other personnel to quickly disconnect the supply in

case of emergencies;

b) selection of the location keeping in view safety against operation by unauthorized

personnel;

c) installation of open type switchboards away from storage batteries or places exposed

to chemical fumes.

d) switchboard should be totally enclosed or made flame proof while installing in damp

situation or where inflammable or explosive dust, vapor or gas is likely to be present;

e) proximity of switchboards while erecting above gas stoves or sinks or any washing

unit in the washing rooms or laundries, or in bathrooms, lavatories or toilets, or

kitchens.

f) conditions to be fulfilled in case of fixing the switchboards unavoidably in places

likely to be exposed to weather, to drip, or in abnormal moist atmosphere;

g) Adequate illumination shall be provided for all working spaces about the

switchboards when installed indoors.

3. Metal-clad switchgear shall preferably be mounted on any of the following types of

boards: e.g. hinged-type metal boards, Fixed-type, Wooden boards etc.

4 Along with building drawings before proceeding with the actual construction of the boards,

a proper drawing showing the detailed dimensions and design including the disposition of

the mountings should be prepared.

5. Code for Arrangement of apparatus should be mentioned; e.g.

a) Equipment which is in front of a switchboard;

b) Projection of apparatus and proximity of fuse body and unnecessary holes from the

edge of the panel;

c) Spacing of the live parts from non-hygroscopic, non-inflammable insulating

material;

d) Arrangement of gear according to its accessibility and connections to all

instruments and apparatus shall also be easily identifiable.

e) In every case in which switches and fuses are fitted on the same pole, these fuses

shall be so arranged that the fuses are not alive when their respective switches are

in off position.

f) No fuses other than fuses in instrument circuit shall be fixed on the back of or

behind a switchboard panel or frame.

Location of Distribution Boards

a) The distribution fuse-boards shall be located as near as possible to the centre of the load

they are intended to control.

b) These shall be fixed on suitable stanchion or wall and shall be accessible for

replacement of fuses, and shall not be more than 2m from floor level.

c) These shall be either metal-clad type, or all-insulated type. But, if exposed to weather

or damp situations, these shall be of the weatherproof type and, if installed where

exposed to explosive dust, vapor or gas, these shall be of flame proof type. In corrosive

atmospheres, these shall be treated with anti-corrosive preservative or covered with

suitable plastic compound.

d) Where two or more distribution fuse - boards feeding low voltage circuits are fed from a

supply of medium voltage, these distribution boards shall be:

1. fixed not less than 2m apart; or

2. arranged so that it is not possible to open two at a time , namely, they are

interlocked and the metal case is marked 'Danger 400 volts' and identified with

proper phase marking and danger marks; or

3. installed in a room or enclosure accessible to only authorized persons.

e) All distribution boards shall be marked 'Lighting' or 'Power', as the case may be, and

also marked with the voltage and number of phases of the supply, Each shall be

provided with a circuit list giving diagram of each circuit which it controls and the

current rating of the circuit and size of fuse element.

f) In wiring branch distribution board, total load of consuming devices shall be divided

as far as possible evenly between the number of ways in the board leaving spare

circuits for future extension.

Circuits and Protection of Circuits

Main distribution board Main distribution board shall be provided with a circuit-breaker on each pole of each circuit, or a

switch with a fuse on the phase or live conductor and a link on the neutral or earthed conductor of

each circuit. The switches shall always be linked.

Branch Distribution Boards Quality or reliability of supply depends upon the proper division of circuits. This part is found

omitted in NNBC.

In this connection, Electrical Installation Guide 2009 published by Schneider Electric, Electrical

Installation of Bureau of Indian Standards and Structure of National Building Code of NEC are

presented for reference.

In Electrical Installation Guide 2009 published by Schneider Electric, ,Chapter P: Residential and

other special locations, following points are recommended:

Subdivision of circuits should be according to the number of utilization categories in the

installation concerned.

At least one circuit for lighting. Each circuit supplying a maximum of 8 lighting points.

At least one circuit for socket-outlets rated 10/16 A, each circuit supplying a maximum of

8 sockets. These sockets may be single or double units (a double unit is made up of two

10/16 A sockets mounted on a common base in an embedded box, identical to that of a

single unit).

One circuit for each appliance such as water heater, washing machine, cooker, refrigerator

etc.

It further recommends the number of 10/16A (or similar) socket-outlets and fixed lighting points,

according to the use for which the various rooms of a dwelling are intended.

Table:-1

Room function Minimum number of

fixed lighting points

Minimum number of 10/16A

socket-outlets.

Living room 1 5

Bed room, lounge, bureau,

Dinning room.

1 3

Kitchen 2 4(1)

Bathroom, shower room 2 1 or 2

Entrance hall, box room 1 1

WC, storage space 1 -

Laundry room - 1

Note:- (1) Of which 2 above the working surface and 1 for a specialized circuit. In addition an

independent socket-outlet of 16A or 20A for cooker and a junction box or socket-outlet for a 32A

specialized circuit.

The Bureau of Indian Standards presents the above table in following way:

Table:-2 A recommended schedule of socket-outlets in a residential building (As per Bureau of

Indian Standard)

Location Number of 5A socket-outlets Number of 15A socket-

outlets

Bed room 2 to 3 1

Living room 2 to 3 2

Kitchen 1 2

Dinning room 2 1

Garage 1 1

Refrigerator 1

Air-conditioner One for each

Verandah 1 per 10m 1

Bathroom 1 1

As per the Bureau of Indian Standards :

Branch distribution boards shall be provided with a fuse or a miniature circuit breaker or both

of adequate rating/setting on the live conductor shall be connected to a common link and be

capable of being, disconnected individually for testing purposes. At least, one spare circuit of

the same capacity shall be provided on each branch distribution board.

In residential installation, lights and fans may be wired on a common circuit. Such sub-circuit

shall not have more than a total of ten points of lights, fans and 5A socket outlets. The load of

such circuit shall be restricted to 800 watts. If a separate fan circuit is provided, the number of

fans in the circuit shall not exceed ten. Power sub-circuits shall be designed according to the

load but in no case shall there be more than two 15A outlets on each sub-circuit.

In industrial installations, the branch distribution board shall be totally segregated for single-

phase distribution and wiring.

In industrial and other similar installations requiring the use of group control for switching

operation circuits for socket outlets may be kept separate from fans and lights. Normally, fans

and lights may be wired on a common circuit, however, if need is felt separate circuits may be

provided for the two. The load on any low voltage sub-circuit shall not exceed 3,000 watts. In

a case of new installation, all circuits and sub-circuits shall be designed by making a provision

of 20 percent increase in load due to any future modification. Power sub-circuits shall be

designed according to the load but in no case shall there be more than four outlets on each sub-

circuit.

In the same way, in this Chapter ―Protection of Circuits‖, the Bureau of Indian Standards states

that:

a) Appropriate protection shall be provided at switchboards and distribution boards for all

circuits and sub-circuits against short circuit and over current and the protective apparatus

shall be capable of interrupting any short circuit current that may occur, without danger.

The ratings and settings of fuses and the protective devices shall be coordinated so as to

afford selectivity in operation.

b) Where circuit-breakers are used for protection of a main circuit and of the sub-circuits

derived there from, discrimination in operation may be achieved by adjusting the

protective devices of the sub main circuit-breakers to operate at lower current settings and

shorter time-lag than the main circuit-breaker.

c) Where HRC type fuses are used for back-up protection of circuit-breakers, or where HRC fuses are used for protection of main circuits, and circuit-breakers for the protection

of sub-circuits derived there from, in the event of short-circuits protection exceeding the

short-circuits capacity of the circuit-breakers, the HRC fuses shall operate earlier than the

circuit-breakers; but for smaller overloads within the short-circuit capacity of the circuit-

breakers, the circuit-breakers shall operate earlier than the HRC fuse blows.

d) If rewirable type fuses are used to protect sub-circuits derived from a main circuit

protected by HRC type fuses, the main circuit fuse shall normally blow in the event of a

short-circuit, although discrimination may be achieved in respect of overload currents. The

use of rewirable fuses is restricted to the circuits with short-circuit level of 4 kA; for higher

level either cartridge or HRC fuses shall be used.

e) A fuse carrier shall not be fitted with a fuse element larger than that for which the carrier is

designed.

f) The current rating of a fuse shall not exceed the current rating of the smallest cable in the

circuit protected by the fuse.

g) Every fuse shall have its own case or cover for the protection of the circuit and an indelible

indication of its appropriate current rating in an adjacent conspicuous position.

9.6

9.7 National Electric Code (NEC) in Structure of National Building Code (NBC) Articles

210 addresses "branch circuits" (as opposed to service or feeder circuits) and

receptacles and fixtures on branch circuits. There are requirements for the minimum

number of branches, and placement of receptacles, according to the location and

purpose of the receptacle outlet.

9.8 It suggests that a ground fault circuit interrupter (GFCI) is required for all receptacles

in wet locations, e.g: outlets in bathrooms, outdoors and kitchens, and, in addition, for

dwelling units: crawl-spaces, garages, unfinished basements, and within 6 feet (1.8 m)

of a wet-bar sink, with limited exceptions. The NEC also has rules about such things as

how many circuits and receptacles/outlets should be placed in a given residential

dwelling, and how far apart they can be in a given type of room, based upon the typical

cord-length of small appliances (for example, not more than 12 feet (3.66 m) apart, or 4

feet (1.22m) apart on kitchen countertops).

9.9

Safety device introduced with the 1999 code is the arc-fault circuit interrupter (AFCI). This device

detects arcs from hot to neutral that can develop when insulation between wires becomes frayed or

damaged. While arcs from hot to neutral would not trip a GFCI device since current is still

balanced, circuitry in an AFCI device detects those arcs and will shut down a circuit. AFCI

devices generally replace the circuit breaker in the circuit. They are required in new construction

on all 15A, 20A circuits to bedrooms, where most arc fault fires originate.

Rating of Cables and Equipments-

Current Rating of the Distribution Fuse Board should be mentioned in the code.

Lighting and Level of Illumination

9.10 As per the Facilities Standards for the Public Buildings Service of the US General

Administration Service, the lighting should be designed to enhance both the overall

building architecture as well as the effect of individual spaces within the building.

9.11

Interior Lighting - Consideration should be given to the options offered by direct lighting,

indirect lighting, down lighting, up lighting and lighting from wall or floor-mounted fixtures.

9.12 Illumination Levels - For lighting levels for interior spaces values are given in the Table-

3 below.

9.13

Table-3 Interior Illumination Levels (Average)

Area Nominal Illumination Level in

Lumens/Square Meter (lux)

Office Space

Normal work station space, open or closed offices1 500

ADP Areas 500

Conference Rooms 300

Training Rooms 500

http://en.wikipedia.org/wiki/Residual-current_device

http://en.wikipedia.org/wiki/Arc-fault_circuit_interrupter

Area Nominal Illumination Level in

Lumens/Square Meter (lux)

Internal corridors 200

Auditoria 150-200

Public Areas

Entrance Lobbies, Atria 200

Elevator Lobbies, Public Corridors 200

Ped. Tunnels and Bridges 200

Stairwells 200

Support Spaces

Toilets 200

Staff Locker Rooms 200

Storage Rooms, Janitors‘ Closets 200

Electrical Rooms, Generator Rooms 200

Mechanical Rooms 200

Communications Rooms 200

Maintenance Shops 200

Loading Docks 200

Trash Rooms 200

Specialty Areas

Dining Areas 150-200

Kitchens

Kitchens 500

Out leased Space 500

Physical Fitness Space 500

Child Care Centers 500

Structured Parking, General Space 50

Structured Parking, Intersections 100

Structured Parking, Entrances 500 1 Level assumes a combination of task and ceiling lighting where systems furniture is

used. (This may include a combination of direct/indirect fixtures at the ceiling for

ambient lighting.)

NOTE: To determine footcandles (fc), divide lux amount by 11.

9.14

9.15 Accessibility for Servicing. Careful consideration must be taken in the design of lighting

systems regarding servicing of the fixtures and replacement of tubes or bulbs. This

issue needs to be discussed with building operation staff to determine the dimensional

limits of servicing equipment.

Light Sources. Generally, interior lighting should be fluorescent. Downlights should be compact

fluorescent; high bay lighting should be high intensity discharge (HID) type. HID can also be an

appropriate source for indirect lighting of high spaces. However, it should not be used in spaces

where instantaneous control is important, such as conference rooms, auditoria or courtrooms.

Dimming can be accomplished with incandescent, fluorescent or HID fixtures, although HID and

fluorescent dimmers should not be used where harmonics constitute a problem. Incandescent

lighting should be used sparingly. It is appropriate where special architectural effects are desired.

It is essential that adequate provision shall be made for all the electrical services which may be

required immediately and during the intended useful life of the building.

Indian Bureau of Standards refers that when considering the function of artificial lighting,

attention shall be given to:

a. illumination and its uniformity;

b. special distribution of light. This includes a reference to the composition of diffused and

directional light, direction of incidence, the distribution of luminance and the degree of glare;

and

c. colour of the light and colour radiation.

1. The variety of purposes which have to be kept in mind while planning the lighting

installation could be broadly grouped as:

a. industrial buildings and processes;

b. offices, schools and public buildings;

c. surgeries and hospitals; and

d. hostels, restaurants, shops and residential buildings.

2. It is important that appropriate levels of illumination for these and the types and positions

of fittings determined to suit the task and the disposition of the working plans.

Electrical System Standards and Design Guidelines, Wisconsin Department of

Administration Division of State Facilities (DSF) suggests that;

General Design

The lighting design shall be practical, energy-efficient, easy to maintain, and appropriate for

the intended function of the space.

The lighting design for new and renovated buildings with windows and significant daytime

occupancies require careful coordination between the lighting designer and the architect.

Interior Lighting

Lighting of interior areas shall utilize fluorescent lighting sources. Incandescent or HID

sources shall be used only for specific isolated applications and justified by program or usage.

For ambient lighting design, utilize 4‘ T8 lamps as much as possible. For ease of maintenance

and lamp storage requirements, the lighting design should utilize a minimum number of

different lamp types. Minimize the use of 2‘ fixtures,

Indirect/direct fixtures shall be used in day lighted zones per DSF Daylighting Standards for

State Facilities guidelines. When the recommended indirect or direct/indirect lighting system

is not applicable, use parabolic fixtures for ambient lighting.

For the DSF Daylighting Standards for State Facilities guidelines, low-wattage task lighting

shall be an essential component of the lighting design. The lighting designer, architect, user

agency, and DSF project manager shall discuss and reach a common understanding as to the

task lighting that will be provided. DSF recommends task lighting be fixed where possible,

and utilize low-wattage fluorescent lamps.

For high/low bay applications such as gymnasiums, warehouses, swimming pools and shop

areas, consider the use of fluorescent fixtures with specular reflectors. Otherwise, utilize

enclosed metal halide fixtures, especially if area is subject to dirt or dust.

Proper design provisions shall be made to ensure that adequate support for mounting of

lighting fixtures is present. Add fixture mounting details to drawings, as appropriate.

Exterior Lighting

Outdoor lighting shall use metal halide lamps (design based on pulse-start lamps). A different

lamp source may be used if needed to match existing lamps.

Exterior lighting shall typically be fed from panels in an adjacent building, and shall be

controlled by a photocell, time clock, or campuswide lighting signal system.

Outdoor lighting system design shall utilize cutoff type fixtures which minimize the amount of

lamp lumens which are emitted above the horizontal plane of the fixture and which minimize

the spillage onto adjacent facilities.

Lighting Controls

Lighting controls and switching shall be kept simple, inexpensive, and easy-to-maintain.

Architectural lighting control systems (scene lighting controls), low-voltage switching

systems, digital control systems, or whole-building programmable control systems utilizing

multiple control panels, shall be used only when necessary. These systems may be considered

only for lighting control in lecture halls, auditoriums and theaters, for switching of large areas,

or for specific energy-saving requirements.

Keep usage of dimming controls to a minimum (only when necessary per program).

Occupancy sensors shall be used as much as practical (occupancy sensors shall typically be

used for required automatic light shut-off instead of central time-clock control or central

energy-management system control). Consider their use in all restrooms, classrooms,

conference rooms, open office spaces, individual offices, and corridors. Use infrared or

passive sound detection occupancy sensors (or combination of these types) only, - no

ultrasonic sensors allowed.

Day lighting/photo sensors shall be used to provide stepped or multilevel on-off switching of

lighting in daylight areas. Care shall be taken in setting up the control sequence to prevent

short cycling of the controls.

Single offices shall typically be provided with 3-lamp fixtures, with bi-level switching of the

inboard and outboard lamps. Provide a wall-mounted occupancy sensor located at the door.

For day light single offices, photo sensors which provide stepped day-lighting control shall be

considered (occupancy sensor shall over-ride photo sensors).

Consider digital timer switches for storage areas, closets, and electrical/mechanical rooms.

(Fixtures in electrical/mechanical rooms shall be fed by emergency generator circuits).

For campus lecture halls and auditoriums, coordinate lighting design with the audio/visual

technology requirements. Speaker/instructor area lighting, projection screen lighting, and

note-taking lighting shall be considered.

Egress / Emergency / Night Lighting

Emergency lighting shall powered by circuits from a building‘s emergency (generator) system.

Emergency battery lighting units shall only be used in buildings without a backup generator.

It is the intention of DSF that egress or emergency lighting be illuminated for those portions of

a building that are, in fact, occupied. To prevent the illumination of egress or emergency

lighting during times that an area is not occupied, DSF recommends the use of occupancy

sensors to provide automatic shut-off of this lighting. Lighting shall be installed in an un-

switched night-lighting mode only when necessary (security applications).

For another method of controlling emergency lighting, consider the use of transfer switch

devices which switch the AC ballast from a switched normal circuit to a generator circuit, -

avoiding wiring emergency fixtures as nightlight fixtures.

4. Wiring

In this heading, the code includes many clauses especially from the Bureau of Indian

Standards. But still following points, which are based on NEC, are better to be

considered:

4.1. Consideration of the voltage drop while calculating and selecting the cable size and fuse.

4.2. Cross-sectional-area (c.s.a.) of conductors

The c.s.a. of conductors and the rated current of the associated protective device depend on:-

a) the current magnitude of the circuit,

b) the ambient temperature,

c) the kind of installation, and

d) the influence of neighbouring circuits .

Moreover, the conductors for the phase wires, the neutral and the protective conductors of

a given circuit must all be of equal c.s.a. (assuming the same material for the conductors

concerned, i.e. all copper or all aluminum).

The following table indicates the c.s.a. required for commonly-used appliances Protective

devices 1 phase +N in 2x9 mm spaces comply with requirements for isolation, and for

marking of circuit current rating and conductor sizes.

Table-4

c.s.a. of conductors and current rating of the protective devices in residential installations

(c.s.a. of aluminum conductors are shown in brackets)

Type of circuit 1-

phase 230V

1-ph+N or 1 ph+PE

c.s.a. of conductors Maximum

power

Protective device

Fixed lightning 1.5 mm2

(2.5mm2)

2,300W Circuit-breaker 16 A

Fuse 10 A

10/16 A 2.5 mm2

(4 mm2)

4,600 W Circuit –breaker 25 A

Fuse 20 A

Indivisual –load circuits

Water heater 2.5 mm2

(4 mm2)


Fuse 20 A

Clothes-washing machine 2.5 mm2

(4 mm2)


Fuse 20 A

Cooker or hotplate1 6 mm2

(10 mm2)

7,300 W Circuit-breaker 40 A

Fuse 32 A

Electric space heater 1.5 mm2

(2.5 mm2)

2,300 W Circuit-breaker 16A

Fuse 10 A

Note- (1) In a 230/400 V, 3-phase circuit, the c.s.a. is 4 mm2 for copper or 6 mm2 for

aluminium, and protection is provided by a 3d2 A circuit –breaker or by 25 A fuses.

Layout and Installation Drawing:

National Rules for Electrical Installation, Third Edition Amendment No.1, Electro-Technical

Council of Ireland Limited 2001 suggests that:

Wiring shall be so arranged and fixed that it cannot be used to support items such as

clothing.

In attic spaces, care shall be taken to lay wiring in an orderly manner and in such a way as

to minimize the risk of damage to the wiring.

The earthing contact in a socket-outlet shall be connected to the protective conductor. The

metal enclosure of a socket-outlet shall be connected to the protective conductor; fixing

screws shall not be used for this purpose.

Laws, Rules and Wiring Standards of North Dakota states that:

Electrical Installations shall be planned to provide adequate capacity for the load.

Wiring system shall have conductors of sufficient capacity to furnish each outlet without

excessive line loss or voltage drop. The voltage drop shall not exceed five percent at the

farthest outlet of power, heating and lighting loads or combinations of such loads.

Material shall be listed by nationally recognized testing laboratories to safeguard life and

property. It is the duty of the electrical installer to secure permission from the executive

director to use materials, devices, and methods of installation not specifically covered by

these standards.

When wiring public school buildings approval shall be received from the department of

public instruction and the state electrical board.

Overhead conductors shall not cross over water wells or known sites where water wells

may be drilled. A minimum distance of 6.10m in all directions shall be maintained for

overhead conductors.

All hospitals, nursing homes, and related patient care areas along with dormitories

designed to house more than sixteen people shall be wired in metal raceway. Portable

cleaning equipment receptacle outlets shall be installed in corridors and located so that no

point in the corridor along the floor line, measured horizontally, is more than 7.62 m from

an outlet, spacing of receptacle outlets for dormitories and assisted living shall be

conformity with section 210.60,2005 edition, NEC.

In the wiring of nursing homes and hospitals, reference shall be made to the state

department health for special requirements pertaining to operating rooms, delivery rooms,

and emergency lighting.

All electrical wiring shall be copper. No aluminum or copper clad aluminum wire shall be

installed in any electrical installation without written permission from the chief electrical

inspector prior to installation.

Kelly Smith in ―Typical Electrical Building Code‖ writes that:

While planning general requirements for wiring an installation position of wall- light switches

in the rooms such as bed room, kitchen, dinning room etc shall be stated. Here is an example

of that:

a) Bedrooms, living rooms and dinning room

Wall light switch should be provided near the entry door,

Each wall must have at least one receptacle.

One or more receptacles must be provided in 4m of interval.

Light fixtures must of on 15 ampere circuit.

b) Kitchen

Larger appliances such as refrigerator should be placed on dedicated circuits.

Receptacles above countertops used for small kitchen appliances must be GFCI

receptacles, controlled by two 20 amp circuits.

c) Electric wiring for Bathroom

Bathroom is a damp environment. Hence receptacles should be GFCI-protected.

Lights must be protected with a globe or something similar to keep moisture at bay.

Depending on amperage use, heaters, lights and fans must be on their own circuits.

d) Outdoor use

It must be underground feed cable (UF) or sealed conduit must be used.

e) Bathrooms and showers.

Bathrooms and showers rooms are area of high risk, because of the very low resistance of

the human body when or immersed in water. Precaution to be taken, are therefore

correspondingly rigorous, and the regulations are more severe than those for most other

locations.

Fittings and Accessories This part is found missing in the NNBC.

EARTHING In this Chapter, following clauses should be considered in the code.

Equipment to be Earthed — Except for equipment provided with double insulation, all the non-

current carrying metal parts of electrical installations are to be earthed properly. All metal

conduits, trunking, cable sheaths, switchgear, distribution fuseboards, lighting fittings and all other

parts made of metal shall be bended toghethcr and connected by means of two separate and

distinct conductors to an efficient earth electrtode.

Structural Metal Work — Earthing of the metallic parts shall not be effected through any

structural metal work which houses the installation. Where metallic parts of the installation are not

required to be earthed and are liable to become alive should the insulations of conductors become

defective, such metallic parts shall be separated by durable non-conducting material from any

structural work.

System of Earthing—Equipment and portions of installations shall be deemed to be earthed only

if earthed in accordance with either the direct earthing system, the multiple earthed neutral system

or the earth leakage circuit-breaker system.

Drawings of earthing should be attached.

Telecommunication and other services

In this chapter following codes are required to be considered:

House wiring of telephone subscribers offices in small buildings is normally undertaken by the

Telephone Department on the surface of walls. But in large multi-storied buildings intended

for commercial, business and office use as well as for residential purposes, wiring for

telephone connections is generally done in a concealed manner through conduits.

The requirements of telecommunication facilities like Telephone connections, Private Branch

Exchange, Intercommunication facilities. Telex and Telegraph lines are to be planned well in

advance so that suitable provisions are made in the building plan in such a way that the

demand for telecommunication services in any part of the building at any floor are met at any

time during the life of the building.

Layout arrangements, methods for internal block wiring and other requirements regarding

provisions of space, etc, may be decided defending as the number of phone outlets and other

details in consultation with Engineer/Architect and user.

Common Antenna System for TV Receivers

In multistoried apartments, houses and hotels where many TV receivers are located, a common

master antenna system may preferably be used to avoid mushrooming of individual antennas.

Master antenna is generally provided at the top most convenient point in any building and a

suitable room on the top most floor or terrace for housing the amplifier unit, etc, may also be

provided in consultation with the architect/engineer.

From the amplifier rooms, conduits are laid in recess to facilitate drawing coaxial cable to

individual flats. Suitable 'Tap Off boxes may be provided in every room/flat as required.

Lightning Protection of Building

Lightning is a natural hazard that causes serious economical losses and personal injuries and

deaths in many parts of the world. In the world, over 20,000 people are affected by lightning and

succumbed to injuries every year. The number of people survive with life-time injuries, temporary

disabilities and psychological trauma may be several times more than that.Nepal is prone to

lightning hazards. So, protection from lightning is one of the important factors to consider in

building code.

Under this chapter, it is necessary to point out the structures which need to be protected from

lightning. For example, Schools, hospitals, auditoria etc are places where a large number of people

congregate; Brick buildings or buildings with thatched roof which have greater degree of risk of

lightning stroke; relatively exposed buildings; buildings of hilly or mountainous area etc.

For the assessment of the lightning hazards, risk index with explanation should be given in the

tabular form in the code. In addition to these methods, protection from lightning also is

recommended to include.

Appendix-11: REVIEW & RECOMMENDATION FOR

REVISION OF NNBC (NNBC 208:2003) SANITARY AND

PLUMBING DESIGN REQUIREMENTS

10 1. INTRODUCTION TO PLUMBING SERVICES IN NNBC FOR REVISION AND

UPDATE

The section ―SANITARY AND PLUMBING SERVICES‖ shall cover the basic

requirements for water supply, sanitation, gas supply, A/C, Ventilation, Chimneys, fire

fighting hose and pipelines, drainage and sewerage for residential, high rise buildings,

government office complexes, business, Industrial buildings and urban areas. The Water

Supply and Sanitation Code shall cover from city dwellings, to commercial complexes and

traffic terminal stations. It shall cover and deal with general requirements of plumbing

connected to municipal water supply and sanitation system.

Apart from the water supply it should cover the design, layout, construction, and

maintenance of drains for foul water, surface water, subsoil water and sewage along with

all ancillary works such as connections, manholes, inspection chambers, water storages

tanks. Each building should be connected to disposal system such as public or private

sewer or individual sewerage including cesspool, soak away or to other approved point of

disposal /treatment plants.

The section should include all the controlling design parameters for the designer to achieve

reliable water supply, sewerage disposal and treatment system design.

However, the present code of NNBC 208 disseminates valuable design parameters, but

possesses following discrepancies and inappropriate parameters and which should be

avoided during updating. They are:

Unit conversion mistakes

Missing sub headings for tables and nomograph

Lack of sample example to use code

Using consistent unit to the terminology e.g. (Residual head be referred to Meters

instead of Pressure unit)

As foreseen the requirement for update of NNBC, the consultants suggest and recommend

focusing on the following issues as well:

Rationalization of definitions, and inclusions of more terms and terminology.

Include first design parameters such as minimum and maximum flow through taps,

residual head, minimum slope, minimum cover etc

Include friction head loss diagram in form of nomograph, tables and appropriate equation.

Make provisions related to domestic hot water supply installation

Make provisions related to water supply and sanitation in high altitude and sub-zero

temperature regions of the country,

Include inspection, testing maintenance requirement.

Include sizing of rain water pipes for roof drainage in more rational basis, and techniques

for rainwater harvesting,

Requirement of refuse chute, if any

Include a code for solid waste disposal, management and treatment, and Environmental

pollution.

Design and Installation pipes and fittings should not be encased in structural element such

as beams, slab, and columns) by chiseling or by any means.

Overhead water storage facilities for the high rise buildings must be located in consultation

with the structural designer.

Water storage facilities shall be provided for each two to three floors with separate

distribution system to each floors for the high rise building.

Provision for storing rainwater in the highest floor is recommended and its uses be limited

to flushing of toilets, fire fighting and cleaning and its overflow be connected to the ground

water recharge well.

Water treatment and waste treatment is a must for the high-rise building. No wastewater

and sewerage be allowed to dispose in the public sewer untreated.

With due consideration to above facts, a comprehensive design code could be formulated

which shall be user friendly and comfortable in adaptation and use of NNBC.

The NNBC Section-208 is thoroughly studied for commenting and compared with other codes

such as National Building code of India-1970, and 2005, International Building Code

(International Plumbing Code), Byelaws prepared by DUDBC/Town development

committees, WHO publications and requirements. However, due to unavailability of latest

International Plumbing Code, the comparison of NNBC code could not be done. Besides,

International Plumbing code, NNBC has been compared and checked with Water Treatment

Hand Book: Degremont – 1979.

The findings and inferences, problems and issues derived during study are written in

commentary and suggestion form with articles related in the NNBC publication. All these

issues and problems are to be resolved and updated by the concern through the panel

discussions on the raised issues and shall be adopted in future in the revised code. Thus

specific technical details, languages, spellings and grammar concerning the ―Plumbing

Services‖ are discussed below with the technical suggestions, formatting and comments etc.

All these suggestions are to be scrutinized by the panel of sanitary engineers, public health

engineers, and environmentalist.

TECHNICAL ISSUES AND PROBLEMS IN NNBC PART 208:

Code may be written in standard format as suggested below or in any other internationally

accepted format of IBC or UBC:

SCOPE

TERMINOLOGY

PREFACE

DESIGN OF

DISTRIBUTION

SYSTEM

MATERIALS FITTING

AND APPLIANCES

LICNSING

OF PLUMBERS

INSPECTION

AND TESTING

GUIDELINES TO

MAINTENANCE

WATER SUPLY

REQUIREMENT

FOR BUILDING

FORMAT FOR

APPLICATION FOR

OBTAININGFOR

PIPING &

DISTRIBUTION

GENERAL

REQUIREMENT OF PIPE

WORK

LAYING OF

PIPES

JOINTING OF

PIPES

WATER STORAGE

HOT WATER SUPPLY

SYSTEM

CLEANING &

DISINFECTION

APPENDIX: (Eg)

1.

2.

3.

4.

DRINKING WATER

QUALITY

SIMPLE

METHOD FOR

IMPROVING W.Q.

w.a.

1.1. NNBC : SECTION (A) WATER SUPPLY

This section deals basically with requirements of water supply, distribution and storage for

the design and construction.

In Last Line of para (1) including fire fighting may be relocated and provision/ system for

fire fighting may be separately included. However, water requirement for the fire fighting

may be included in the Water requirement table.

1.2 REVIEW WATER SUPPLY REQUIREMENTS FOR BUILDINGS:

The water requirements in each type of dwelling is studied and compared as below:

S. No. Type of Buildings Minimum Requirements per head per day

NNBC Nepal NBC-INDIA WHO/EO REMARKS

1. Apartment Buildings 100 lit 135 135 RR

2. Auditorium (per seat) 15 lit 15

3. Hospital (inc. laundry)/ bed

(a) # of beds <100 340 lit 340

(b) # of beds >100 450 lit 450

4. Cold Storage 45 lit

5. Buildings higher than 4 st.

Commercial & Industrial

45 lit

5.1 Nurses Home & Medical

Quarters

135 lit. 135 RR

RECOMMENDED

6. Residences 100 lit. 135 135 RR

7. Office 45 lit. 45

8. Hostels (Qty. for Nurses

etc.)

100 135

9. Hotels per bed 100 180 180 RR

10. Restaurants (per seat) 50 70 70 RR

11. Schools & College

(a) Day Schools 15 45

(b) Boarding Schools 100 135 135 RR

12. Cinemas, Theatre Halls,

Concert Halls (per seat)

15 lit. 15

13. Factories

(a) With bathing facilities 45 lit 45

(b) W/o bathing facilities 30 lit 30

14. Terminal Stations (Bus and

Railway per pass)

15 lit 45/23 45 RR

15. Airports (Internationals) 70 lit. 70/70

16. Airports (Domestic) 20 lit. 70/70 70 RR

Increase or decrease of water requirement depends upon flushing system of toilets. Water

requirement may be allowed to reduce for poor flush toilets. Above table gives the

glimpse of water requirement by different standards & agencies, with the consultant

remarks as RR (Note: RR means recommended for review and revision).

While considering for any decrease in minimum water requirement will have severe impact

on the design of municipal water and sewer disposal conveyance. This issue is raised for

the panel discussions while revising the code.

2. WATER STORAGE

1st Para Last line: Storage of water within premises is thus necessary to meet peak demand

In article 2.1.8 Addition of this statement may be useful ―inlet pipe of the w/s line must be

connected with floating valves where municipal supply is connected to the underground or

overhead water tanks.

2.2 UNDERGROUND STORAGE

In article 2.2.2, Sizing and capacity of the tanks should be left to the designer than to

specify in the code

In article 2.2.3,Tank should not be built or placed closed to manhole, septic tank or soakpit

Minimum distance specified in the code may be increased.

Addition of this statement will be useful ―Inlet should be closed by floating valve.‖

2.3 OVERHEAD STORAGE

Addition of this statement will be useful ―Inlet pipe should not be closed by floating value

if pumped.‖

Table A2 may require revision, the designer may be allowed to determine its capacity

requirement.

Before writing above, terminology of each item needs to be mentioned in code such as:

Airlock, Air gap, Available Head, Residual Head, back flow, Backflow preventer, Back

siphon age, Branch, Cross-connections, communication pipe, consumer, consumer's pipe,

orifice, diameter, nominal diameter, direct tap, down take pipe, effective opening, feed

cistern, float operated value, check value or unidirectional value, gate value, ball valve, air

releasing value, flushing cistern, general washing place, geyser, horizontal pipe, hot water

tank or cylinders, offset, period of supply, pipe work, plinth, plumbing, potable water,

service pipe, stop cock, stop tap, storage tank, supply line, supports, terminal pressure,

vertical pipe, warning pipe, wash out value, water level, water main, water outlet, water

supply system, water works, leakage ferrules, authority having jurisdiction.

3. DISTRIBUTION SYSTEM & PIPEWORKS

In article 3.1, the formulae recommended for pipe network design is valid for pipe sizes

greater than 100 mm and higher velocity.

For internal plumbing pipe networks are based upon Darcy – Weisbach equation.

Viz: d**2

*l*f*4i

2

Hg

v

Where f: Head loss in meter in the section

f: friction co-efficient

l: length of pipe in m

v = velocity of flow in m/sec

g = 9.81 m/sec2

d = diameter of pipe in meter (Internal)

f is estimated by f = 0.005 d400

11 : d internal diameter of pipe in m.

f for new galvanized pipe is 0.006.

Minimum discharge may be specified which may be.

Q = 0.15 liter per second in House hold taps.

Q = 0.25 lit per second in Public tap stand.

Minimum velocity of discharge

v = 1 m/s to 3m/s.

Minimum residual head = 1.8 – 3.5 meter (0.18 to 0.35 kgf/ cm2).

In article 3.2, Residual head of 0.018 N/ mm2 (1.8 kg/cm

2 ) at consumer's tap

This statement is either mistaken in unit conversion or typo mistake, which requires

revision as such large residual head ask for large pipes and extra pumps will be required to

generate such a high head.

Hazen Williams formulae

v = 0.85 C R0.63

S0.54

can be used for Turbulent flow above 3 liter per second.

This equation will be reduced to:

85.1

1.165 c

v

D

l*78.6hf

where l : length of pipe in meter

v : velocity of pipe

d : diameter of pipe in meter

c: a constant depending upon the roughness of pipe which is taken generally

100 value.

If calculation is made by these two formulae head loss for 12 mm internal dia GI pipe will

be 1.76 m to 10 meter length of pipe by Darcy – Weisbach equation & 3.96 m for 10 meter

length of pipe by Hazen Williams which mean larger diameter pipes will be required in

household plumbing works. Therefore, Hazen Williams Equation is considered valid for

the distribution network design with higher supply. Alternatively, Prandtle Colebrook egn:

is valid for both which is tedious equation: to be solved by iteration is as follows:

d**2

* 2

Hg

vf where;

Hf = Loss of head in the pipe due to friction in meter of water column per m length of pipe

۸ = head Loss Coefficient

k = equivalent roughness coefficient of the wall of conduit in m

l = length of pipe in meter

v = velocity of pipe

d = diameter of pipe in meter

g = 9.81 m/sec2

Values of kinematics viscosity, roughness coefficient smooth non corroding piping with

scaling unlikely, and sample calculation, head loss tables nomograph may be developed

and given in this section to help the designer.

In article 3.7, Addition of this statement will be useful ‖90 cm or above soil cover is

required for High density polyethylene pipe (life of pipes deterioration with exposure of

pipe in sunlight due to VV rays).

In article 3.9, the quality & selection of pipes depend upon the quality of water to be

conveyed. The code may define the quality of potable water, which may be as follows:

MINIMUM STANDARD OF WATER QUALITY

S.

No.

Parameters Unit Standard/ Goal EU/

Standard

Recommended

1. Coliform /100ml Not be

detectable

2. Lead (Toxicity factor) mg/1 0.1

3. Manganese mg/l 0.05

4. Fluoride mg/l 1.5

5. Iron (Fe) mg/l 0.10

6. Phenols mg/l <0.002

7. Nitrate mg/l 45

8. Nitrate mg/l 0.10

9. Ammonium mg/l 0.05

10. Ammonium mg/l <0.035

11. Oxygen mg/l 7.5

12. Oil mg/l 0.01

13. Color Co-

Scale

5

14. Taste/ Odor D.N Unobjectionable

15. Turbidity F.TV 5

16. Suspended Solids mg/l 5

S.

No.

Parameters Unit Standard/ Goal EU/

Standard

Recommended

17. Hardness mmol/l 1.0

18. Ca++ Aggressivity mg/l <200>75

19. Mg++ mg/l 1.50

20. Saturation Index mg/l 0<0.5

21. PH mg/l 8-8.3

22. CO2

mg/l -

23. HCO3 mg/l -

24. TDS mg/l 500

25. Alkalinity mg/m3 200

26. Chlorophy II mg/m3 <5

27. So4- mg/m3 200

28. Temperature ºC. 15-27

29. Chlorides mg/l 200

30. Lindane mg/l -0.004

31. Phenolic Compounds mg/l 0.002

32. Detergent mg/l 0.20

In article 3.7 the addition of this statement may be useful ―90 cm or above soil cover is

required for high density polyethylene pipes (life of pipes deteriot with exposure of pipe in

sunlight due to VV rays).

In article 3.9, the quality & selection of pipes depend upon the quality of water to be

conveyed. The code should define the quality of potable water which may be as follows:

S.

No.

Parameters Unit Standard/

Goal

EO/

Standard

Recommended

1. Coliform /100 ml No coli.

2. Lead (Toxicity factor) mg/ 1 0.1

3. Manganese mg/l 0.05

4. Fluoride mg/l 1.5

5. Iron (Fe) mg/l 0.10

6. Phenols mg/l <0.002

7. Nitrate mg/l 45

8. Nitrate mg/l 0.10

9. Ammonium mg/l 0.05

10. Phosphate mg/l <0.035

S.

No.

Parameters Unit Standard/

Goal

EO/

Standard

Recommended

11. Oxygen mg/l 7.5

12. Oil mg/l 0.01

13. Color Co-scale 5

14. Taste/ odor D.N. Unobjectio

nable

15. Turbidity F.TU 5

16. Suspended solids mg/l 5

17. Hardness mg/l 1.0

18. Ca++ Aggressivity mg/l <200>75

19. Mg++ mg/l 1.50

20. Saturation Index mg/l 0<0.5

21. PH mg/l 8-8.3

22. CO2 mg/l -

23. HCO3 mg/l -

24. TDS mg/l 500

25. Alkalinity mg/m3 200

26. ChlorophyII mg/m3 <5

27. SO4– mg/m

3 200

28. Temperature ºC. 15-27

29. Chlorides mg/l 200

30. Lindane mg/l -0.004

31. Phenolic Compounds mg/l 0.002

32. Detergent mg/l 0.20

The following articles may required to be added to the code:

Materials, fittings and appliances

Conveyance, and distribution of water within premises

General requirement for the pipe works

Laying of mains and pipes on site

Jointing of pipes

Storage of water (all ready included in Chapter I)

Hot water supply system

Inspection and testing

Guidelines to maintenance of the system

Page No. 10/11:140 Plumbing: Design & Practice.

It will be appropriate to show level difference between.

Terrace & soffit of overhead water tank

Highest level of water tank and air vent

Cross connection of supply pipe must be avoided

Such cross connection may not be allowed.

Separate supply is maintained to urinal/ commode/ WC to encourage usage of

rainwater.

Water meter required to be shown above street level.

Page No. 12/13. Fire hydrant is required to be encouraged in breakable glass boxes with

hose reel next to it.

A routine check of Air value is required.

B. Waste Water Disposal:

Should this section be renamed as Drainage and Sanitation because waste water disposal is

part of Drainage.

Same structure of code writing may be followed as in water supply.

The more terminology may be defined such as:

Authority having Jurisdiction, Bedding, Barrel, Benching, BOD chair, channel, cleaning

eye, connection, cover, COD, B-coli Depth of man hole, nominal diameter, drain, drainage

work, drop connection, Drop Manhole, E-Coli French drain, rubble drain, fittings, fixture

units, formation haunching, highway authority, interceptor manhole, invert, junction pipe,

manhole, manhole chamber, non-service latrine, puff ventilation, rest bend, saddle, service

latrine, sewer, soakaway, soffit, soil waste, soil pipe, subsoil water, surface water, surface

water drain system of plumbing, two pipe systems, single pipe system, trade effluent, vent

pipe, ventilating pipe, waste pipe, waste water (sullage).

The word ―Collection Systems‖ may be replaced by ―System of plumbing‖

In article 1.4, Word symphonic may be replaced siphonic

In Table B1- Addition of this statement may be useful ‖Preferably bath on each floor.‖

In Table B2- Factories

S.No. 1. (i) 2 for 21-45 persons may be 2 for 16-35 persons.

(ii) Taps word is missing.

In Table B3

In column 4 – 3 para 100 person is too high may be not more than 1 or 2 , 2% percent may

be replaced by 1%.

In column 2 – Water – losets may be replaced water closets.

In column 3 – Urinals 1 for 25 persons is too high may be 1 for 50 person.

In Table B4

In column 4, 2nd

para, 150 persons may replace 159 persons.

Washbasins for female public may be 1 for every 200 persons.

In Table B6

In column 4, Ablution tap may be 1 for each W/C.

Wash basins may be 1 for every 100 persons.

In Table B7

In column 7, Ablution taps may be 1 in each W.C. instead of 5.

In column 3, the rate 2.5 percent may be revised to 3%

Type mistake 2-5 percent should be 2.5%

Baths are preferable in each floor may be discussed and adopted for the

future code

In Table B8 In column five urinals may be 20-45 persons.

In Table B9 v) kitchen sinks two should move one up.

In Table B10

In column 3 1 per 60 may be 1 per 40

Table B12

Fitments shall be corrected to fitments.

2. Disposal of sewage/ wastewater & pipe work.

Descriptive parts required to be split under certain heading of article such as

Preparation & submission of plans & drawings

Drainage and Sanitation Requirement.

Prepare preliminary data for design where damage to buildings and structures are

importantly received.

Design considerations, with layouts, rainfall data

Design, - estimation of flow, methodology for the estimation of flow

- Pipe sizes

- Gradients

- Manhole locations & interval

- Type of manhole

Construction relating to conveyance of sanitary wastes

Selection and Installation of Sanitary Appliances

Inspecting – Testing

Maintenance

Appendix – For Forms/ Format/ Design charts/ table etc.

2.4 Gradients:

In Table B14:

On column 3, the gradient of pipe for each diameter is miscalculated, and requires a

professional review.

1 – 100 mm – 1:35 to get 0.18 m3/min.

2 – 150 mm – 1:65 to get 0.42 m3/min.

and so on in mixed lining with Ks = 55

for polyethylene or PVC or glazed earthen pipe Ks =100

Then gradient will be as follows.

1. 100 mm – 1:125 to get 0.18 m3/min.

2. 150 mm – 1:255 to get 0.42 m3/min.

Manning – Strickler‘s formulae is.

V = Ks * R⅔ * I ½

Where v = mean velocity of flow in m/sec.

R = Hydraulic or mean radius = for circular pipe D/4.

I = Channel gradient

Ks = Wall roughness

Bazin‘s formula.

R

r1

RI87V

wall roughness =ץ

Value of ץ or ks is as follows.

Nature of wall R Ks.

Very smooth walls (PVC, PE, Earthen, Cement Plate) 0.06 100

Walls with ordinary cement rendering - 90

Smooth wall (cement concrete, bricks) 0.16 70-80

Rough walls

Channels with earth walls

Do with pebble bottom & grassy sides

0.46

1.30

1.75

60-70

40

25-35

Kutter‘s Formulae/ Chezy‘s Formula

V = CRI

Where

R

nC013.0

*)1

00155.023(1

1

00155.0123

n = 0.013.

Hazen – williams

V = 0.85 * (R)0.63

* (I )0.54

Similarly in Table B 15 Requires revision, and correct value of gradients requires to be entered.

Based on the above equations suitable, table, nomographs, and chart may be developed and

introduced in the code.

In Illustration B1, it will be nice to print name of Fixture such as wash basin, WC, floor traps,

sinks, siphon etc.

In two pipe system, waste water collection shall be discharged in separate man hole than in sludge

man hole. This system requires the two system pipe in municipal conveyance too.

The rain water collection shall be connected to waste water or separate piping may be indicated in

the map with floor trap in roof terrace of flat nature.

In case of slope roof; rain water may be collected through the provisions of Gutter and down water

pipes

In Illustration B3

Cross-connection of wash basins and sink may be avoided.

Floor trap may be shown

C. Rain Water Disposal

In article 8; asbestos cement pipe/ roofing short may be NOT ALLOWED TO USE.

NNBC code should encourage for rain water harvest than its disposal. One of the cost effective

measure for rain water harvest with be constructing shallow wells of depth 6-9 meter of 1 of 1.5

meter dia and takes the rain water pipe to the well. This well can serve to the community not for

individual. However precaution may be taken in usage of roofing material having health hazard

paints or asbestos. Encouraging to built community wells will be useful for recharging ground

water and serve as the seismic energy dissipater during several earthquake.

D. Gas Supply

Although the present NNBC does no include this chapter, however during revision of the code, it

might be worth while to include in the code for which following considerations are suggested.

Terminology: Customer‘s/ consumer‘s connection gas filter, pilot, pressure regulator, purge

qualified installing agency, riser, service pipe service shut off valve, vent pipe, five extinguishers.

Regulations on usage of LPG/ Methane etc.

Gas pressure regulator valve shall be outside the usage area.

Gas cylinder shall be installed outside in the open area to usage area shall not be placed

below ground.

Portable fire extinguishers to be installed near the gas usage area.

Pipe sizing, piping material, fittings

Inspection of services etc.

E. Miscellaneous

Code does not cover much for rural inhabitant thus code be prepared for rural as well covering

following:

Septic tank, soak pit construction

Poor flush toilet with twin pit

Bio-gas plant

Management of cattle, agricultural, domestic waste

Hot Water Supply and Insulation

The Code may introduce a separate sub section for the Environmental Pollution covering

following:

Outdoor Air Pollution

- Vehicular Traffic

- Usage cow dung, coal etc for kitchen

- Dust pollution

- Domestic waste storage, industrial waste storage

- Usage of pollutants / storage of cosmetics

Indoor Air Pollution

- Dust Control,

- Smell and Odor Control

- Fungus control

- Termite Control

Sound Pollution

- Noise from Generator

- Vehicular Noise

- Concert, Musical Instruments, speakers, etc.

- Operation of Handicraft enterprises

- Storage of gases and petroleum products

- Storage of cosmetics, Lithium Battery

- Storage of explosives and Testing

Water Pollution

- Transmission, Disposal of cattle waste, human waste, domestic waste in and around

rechargeable well, water resources, water sources, abstraction well

- Disposal of industrial waste

- Laundry, Butcher House

- Usage of organic, inorganic chemicals

Solar pollution

- Usages of reflector producing UV rays.

- Usage of reflection materials in building facade

- Usage of reflecting roofing sheet along the landing and take off strip of airplanes

- Obstruction of solar rays by one building to the other especially on south façade

Separate section is provided in the code for the remedial measures for the Environmental

Pollution with inclusion of following articles:

Code for "LANDSCAPING, SIGNS AND OUTDOOR DISPLAY STRUCTURES" Right

for information for peaceful living in urban and rural area.

Limiting transmission of carbon dioxide and carbon mono oxide by the moving vehicle in

the street.

Limiting noise level by vehicle horn, generators.

Limiting the usage of reflectors in the building façade

Limiting the dust collector units in the building façade.

Cleaning building façade

Creating mandatory regulation for planting trees along the sides of existing and newly

constructed road, building, parks and structures, open spaces to minimize the global warming

effect through the usage of carbon dioxide by plants and giving more oxygen to inhabitant.

A separate agency may be created as law enforcement body to check, monitor and bring

awareness amongst the city dwellers not to construct an element that is heath hazaradous and

creates problems to other. If the code is not enforced properly, the time and efforts invested in

the development of nice code may turn into vain.

References:

- National Nepal Building Code – NNBC 208-2003.

- National Building Code of India – 1970, 2005.

- Water Treatment Hand Book: Degremont – 1979

Foundation de I‘EAU – Lemoges.

- Legislation for Drinking Water & Swimming Pools.

2.1 Recommendations of World Health Organization (1972)

WHO Palace of Nations, Geneva

- Legislation covering domestic sewage, and industrial waste water in West Germany,

Belgium, France, Great Britain, Switzerland

- Legislation on Air pollution, France

- Environmental Regulation Hand Book.

- Journal of the Installation of Water Engineers & Scientists.

- Techniques et Science. Municipals,

- Water Supply and Sanitary Engineering – Gurcharan Singh

- Text Book of water Supply & Sanitary Engineering - S.K. Hussain

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