Pipe rack

1

DESIGNING OF STEEL PIPERACK

A PROJECT REPORT

Submitted by

JAYENDRAVEL.S

KESAVRAMAN.S

LARSEN SAMUEL.S

MOHAMED MUZAMIL.B.A

MOHAMED SATHIR.M

In partial fulfillment for the award of the degree

of

BACHELOR OF TECHNOLOGY

in

CIVIL ENGINEERING

BHARATH INSTITUTE OF SCIENCE AND TECHNOLOGY

BHARATH UNIVERSITY

CHENNAI-600 073

APRIL-2011

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BHARATH UNIVERSITY

CHENNAI-600 073

BONAFIDE CERTIFICATE

Certified that this project report “DESIGNING OF STEEL PIPE RACK” Is the

bonafied work of “JAYENDRAVEL.S (U07CE058), KESAVRAMAN.S

(U07CE071), LARSEN SAMUEL.S (U07CE078), MOHAMED MUZAMIL.B.A

(U07CE094), MOHAMED SATHIR.M (U07CE096)”

SIGNATURE SIGNATURE

S.SANKARAN Mr.T.P.MEIKANDAAN

HEAD OF THE DEPARTMENT, SUPERVISOR,

CIVIL ENGINEERING, CIVIL ENGINEERING,

BHARATH UNIVERSITY, BHARATH UNIVERSITY,

CHENNAI - 600 073. CHENNAI - 600 073.

EXTERNAL EXAMINER INTERNAL EXAMINER

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ACKNOWLEDGEMENT

We thank our beloved Chancellor Er. J.Sundeep Aanand for his

commendable support in the achievement of this project with success.

We thank our Vice Chancellor Dr. K.P.Thooyamani for creating an

atmosphere where we can develop our academic skills.

We are privileged to thank our Principal Dr. R.Kari Thangaratnam for the

facilities extended to us during this course.

We would like to extend our sincere thanks to our guide

Mr.T.P.Meikandaan (Sr.Lecturer) Civil Engineering Department who has given

valuable support during the course of our project by clarifying our doubts and

guiding with his novel ideas.

We wish to express our sincere thanks to Dr.S.Sankaran, Professor and

Head of department of civil engineering, Mr.P.Dayakar (Asst.Prof),

Mr.P.Sachinantham (Asst.Prof), and and all other staff members for their

valuable encouragement and guidance during the tenure.

We extent our thanks to all the non-teaching staff of Civil Engg Dept those

who helped us in completing this project successfully.

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ABSTRACT

It is common to overemphasize the structural design of pipe support structures, rather

than focus on Detailing for stability or economics and practical aspects of the steel structure and

the foundations. This is sometimes referred to as over-designing and under-detailing. Sometimes

the hanger-type pipe Supports or the trapezes supported by another structure, such as the main

building frame, are referred to as pipe support structure. For the purposes of this discussion, the

terms pipe racks, pipe supports, and pipe support structures are interchangeable. Essential

elements for limit states of pipe support systems are often ignored, since these systems are

comprised of secondary elements and rarely impact the structural integrity of any industrial

facility. Structural failures of pipe supports are neither documented nor disseminated to the

structural community. The structural design of pipe racks varies widely depending of pipe racks

varies sidely. Depending upon the plant operations and the associated plant standards. However,

pipe rack failures could cause serviceability problems for plant operations. Failures of pipe

support system could potentially impact the health, welfare, and safety of plant personnel die to

pipe breakage or leaks. The Following discussion includes a review of the considerations

involved in the design, detailing, and structural stability of pipe racks. Optimal solutions are still

governed by the judgment of design engineer.

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TABLE OF CONTENTS

CHAPTER TITLE PAGE

NO. NO.

ACKNOWLEDGEMENT i

ABSTRACT ii

LIST OF TABLES vii

LIST OF FIGURES viii

LIST OF ABBREVIATION ix

1 INTRODUCTION 1

1.1 GENERAL 1

1.2 SCOPE 1

1.3 TERMINOLOGY 1

1.3.1 Structure 2

1.3.1.1 Main Cross Beam 2

1.3.1.2 Portal Frame 2

1.3.1.3 Longitudinal Beam 2

1.3.1.4 Width of Piperack 2

1.3.1.5 Piperack Spacing 2

1.3.1.6 Intermediate cross beam 2

1.3.1.7 Longitudinal stability 2

1.4 FOUNDATIONS 3

1.4.1 Footing 3

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1.4.2 Longitudinal Beam 3

1.5 TYPES OF PIPE RACK 4

1.5.1 Conventional Pipe Rack 4

1.5.2 Non Continuous Pipe Rack 4

1.5.3 Modular Pipe Rack 4

2 LITERATURE REVIEW 6

3 DESIGN PROCEDURE 7

3.1 CONVENTIONAL PIPE RACK 7

3.1.1 Data Collection For Pipe Rack Design 7

3.1.2 Design Loads Consideration 8

3.1.3 Load Combinations And Allowable Deflection

Of Pipe Rack 13

3.1.4 Final Anchor And Guide Load Check 15

3.1.5 Allowable Horizontal And Vertical Deflection 15

3.1.6 Framing Of Continuous/Conventional Piperack 15

4 LOAD CALCULATION 19

4.1 PIPE LOAD 19

4.2 WIND LOAD CALCULATIONS AS PER IS 875-3 26

4.2.1 Wind load calculation for the second frame

in grid 1&2 - (X - Direction) 27

4.2.2 Wind Load applied in (Z - Direction) 90 Degree 28

4.2.3 Wind load calculation for the frame

in grid A - (Z - Direction) 29

4.2.4 Wind load calculation for the second frame

in grid B - (Z - Direction) 30

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5 DESIGN OF BASE PLATE 33

5.1 LOADING 33

5.2 DESIGN FOR TENSION 34

5.3 DESIGN FOR COMPRESSION 34

5.4 DESIGN OF BOLTS SUBJECTED TO SHEAR AND TENSION 35

5.5 CALCULATIONS 35

6 DESIGN OF PEDESTAL 37

6.1 PEDESTAL MARK 37

6.2 CALCULATION OF Nuz and K 39

6.3 SECTION DESIGN - RATIOS FOR CHART ENTRY 40

7 Design of Combined Foundation 41

7.1 DESIGN OF COMBINED FOUNDATION "F1" 41

7.1.1 Longitudinal direction ( Z - dir ) 43

7.1.2 Transverse direction ( X - dir ) 44

7.1.3 Pressure Along Z - Direction 45

7.1.4 Load calculations for combined Footing “F1” 47

7.1.5 Design of Strap Beam 50

7.1.6 Check For Shear 51

7.2 DESIGN OF COMBINED FOUNDATION "F2" 52

7.2.1 Longitudinal direction ( Z - dir ) 54

7.2.2 Transverse direction ( X - dir ) 55

7.2.3 Pressure Along Z - Direction 56

7.2.4 Load calculations for combined Footing “F2” 58

7.2.5 Design of Strap Beam 61

7.2.6 Check For Shear 62

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8 CONCLUSION 63

REFERENCE 64

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LIST OF TABLES

TABLE NO. TITLE OF THE TABLE PAGE NO.

4.1 Load Calculation For Pipe Load 19

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LIST OF FIGURES

FIGURE NO. TITLE OF THE FIGURE PAGE NO.

4.1 Shows The Pipe Bridge Is Analysed Using A Structural

Software Program Staad Pro 20

4.2 The Nodes Numbers Of The Pipe Rack 21

4.3 The Beam Numbers Of The Pipe Rack 22

4.4 The Top Plan View Of The Pipe Rack 23

4.5 The View Of Pipe Rack 23

4.6 Shows The Grid 1 And Grid 2 Of The Pipe Rack 24

4.7 The Vertical Pipe Load Of The Pipe Rack 25

4.8 The Wind Load Applied On The Grid 1 And 2 27

4.9 The Wind Load Applied In (Z-degree) 28

4.10 The Wind Load For The Frame A In (Z-direction) 29

4.11 The Wind Load For The Frame B In (Z-direction) 30

4.12 Shear Force Diagram At (Z-direction) 32

4.13 Shear Force Diagram At (Y-Direction) 32

4.14 Bending moment at (Z-direction) 33

4.15 Bending moment at (Y-direction) 33

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LIST OF SYMBOLS AND ABBREVATIONS

SYMBOLS DESCRIPTION

A Total area of section.

Ab Equivalent area of helical reinforcement.

Ac Area of compressive steel.

Ae Equivalent area of section.

Ak Area of concrete core.

Am Area of steel or iron core.

Asc Area of longitudinal reinforcement (comp.)

Ast Area of steel (tensile).

Al Area of longitudinal torsional reinforcement.

Asv Total cross-sectional area of stirrup legs or bent up bars within distance sv.

Aw Area of web reinforcement.

AФ Area of cress-section of one bar.

a Lever arm.

ac Area of concrete.

B Flange width of T-beam.

b Width.

br Width of rib.

C Compressive force.

c Compressive stress in concrete.

c’ Stress in concrete surrounding compressive steel.

cs Permissible tensile stress in concrete.

c1 Compressive stress at the junction of flange and web.

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D Depth.

d Effective depth.

dc Cover to compressive steel.

ds Depth of slab.

dt Cover to tensile steel.

e Eccentricity.

Compressive steel depth factor (=dc/d).

F Shear force,

Fr Radial shear force.

f Stress (in general).

fck Characteristic compressive stress.

fy Characteristic strength of steel.

H Height.

I Moment of inertia.

Ie Equivalent moment of inertia of section.

j Lever arm factor.

Ka Coefficient of active earth pressure.

Kp Coefficient of passive earth pressure.

k Neutral axis depth factor (n/d).

L Length.

Ld Development length.

M Bending moment.

Mr Moment of resistance.

Mt Torsional moment.

Mθ Circumferential bending moment.

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m Modular ratio.

n Depth of neutral axis.

nc Depth of critical neutral.

∑0 Sum of perimeter of bars.

Pa Active earth pressure.

Pp Passive earth pressure.

Pu Ultimate load.

P Percentage steel.

P’ Reinforcement ratio (Au/bd).

pa Active earth pressure intensity.

pe Net upward soil pressure.

pa Passive earth pressure intensity.

Q Shear resistence.

q Shear stress (due to bending).

q’ Shear stress due to torsion.

R Radius ; Resistance factor (=½cjk).

r Radius ; cost ratio of steel and concrete ; L/B ratio.

s Spacing of bar ; standard deviation.

sa Average bond stress.

sb Local bond stress.

T Tensile force ; Thickness of wall ; Torsional moment.

t Tensile stress in steel.

tc’ Compressive stress in compressive steel.

W Point load ; Total load.

X Co –ordinate.

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Z Distance; Co-ordinate.

α Inclination; coefficient.

β Surcharge angle.

γ Unit weight of soil.

γ’ Submerged unit weight of soil.

σcc Permissible stress in concrete (direct comp).

σcc’ Direct compressive stress in concrete.

σcbc Permissible compressive stress in concrete due to bending.

σst Permissible stress in steel in tension.

σst Permissible tensile stress in shear reinforcement.

σst Permissible tensile stress in main reinforcement.

σsy Yield point compressive stress in steel.

μ Coefficient of friction.

τc Shear stress.

Ф Diameter of bar.

τcmax Max. Shear stress.

τv Nominal shear stress.

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CHAPTER – 1

INTRODUCTION

1.1 GENERAL

Pipe rack is the main artery of any plant. This carries the pipes and cable trays (raceways)

from one equipment to another equipment within a process unit (called ISBL piperack) or carries

the pipe and cable trays from one unit to another unit (called OSBL pipe rack). Sometimes you

will also find the air cooled heat exchangers on the pipe rack.

1.2 SCOPE

This design guide defines the minimum requirements for the design of piperack in process

industry facilities at the sites. It covers general design philosophy and requirements to be used in

the analysis and design of piperack. Criteria presented herein pertain to loads, load combinations,

allowable stresses, and superstructure and foundation design.

1.3 TERMINOLOGY

Piperack is a structure made of steel, concrete or mixed supporting :-

- One or more layers of piping.

- Electrical or instrument cable tray.

- Air cooler in certain case.

Piperack comprises of two parts :-

- Steel or concrete structure.

- Concrete foundation.

A piperack composes of various element with the following terminology :-

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1.3.1 Structure

1.3.1.1 Main Cross Beam

The main cross beam is a horizontal beam connected to two posts to form the portal

frame and to support the pipes.

1.3.1.2 Portal Frame

The element of piperack forms by two posts and one or more main cross beams.

1.3.1.3 Longitudinal Beam

The longitudinal beam is a horizontal beam connecting two portal frame in longitudinal

direction. Generally, the members are used to support the lateral forces, intermediate cross beams

and post of coolers. Especially to transmit the horizontal force to the bracing bay.

1.3.1.4 Width of Piperack

The width of piperack is the distance between the axis of the posts.

1.3.1.5 Piperack Spacing

Piperack spacing is the distance between the portal frames.

1.3.1.6 Intermediate cross beam

The intermediate cross beam is a horizontal cross members supported by longitudinal

beams. They are used to reduce the deflection of small pipes. Their requirement is decided by

piping department. The intermediate cross beam shall be steel.

1.3.1.7 Longitudinal stability

Longitudinal stability forms by two consecutive portal frame connected by members

which restraint the longitudinal forces.

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1.4 FOUNDATIONS

1.4.1 Footing

Footing is a member rest on good ground, in the case of pile this is called pipe cap.

1.4.2 Longitudinal Beam

Longitudinal beam is a beam connecting the two consecutive footing in longitudinal

direction.

- Longitudinal beam incorporated with the footing.

- Longitudinal beam rested on the footing.

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- Longitudinal beam semi-incorporated with the footing.

1.5 TYPES OF PIPE RACK

• Continuous Piperack (conventional pipe rack) system

• Non-continuous Piperack system

• Modular Piperack

1.5.1 Conventional / Continuous Pipe rack

Continuous Piperack (conventional pipe rack) system: This is essentially a system where

multiple 2-dimensional (2D) frame assemblies (commonly called bents), comprised of two or

more columns with transverse beams, are tied together in the longitudinal direction utilizing

beam struts (for support of transverse pipe and raceway elements and for longitudinal stability of

the system) and vertical bracing to form a 3D space frame arrangement. Piperacks supporting

equipment such as air-cooled heat exchangers must utilize the continuous system approach.

1.5.2 Non- Continuous Pipe rack

This is a system comprised of independent cantilevered, freestanding 2D frames not

dependent on longitudinal beam struts for system stability. This system, where feasible, should

result in lower total installed cost (TIC).

1.5.3 Modular Pipe rack

Building Modules: Structural Frames completely fitted with miscellaneous equipment

and architectural finishes.

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Piperack Modules: Structural Frames completely fitted with pipes, Cable trays and

miscellaneous equipment.

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CHAPTER – 2

LITERATURE REVIEW

Kasi V. Bendapudi, P.E., S.E. Structural steel pipe supports are extensively utilized in

industrial and manufacturing facilities. Lack of uniform industry standards for this topic leads to

each organization adopting its own engineering standards, at times, without a clear understanding

of the underlying theoretical concepts and the cost implications. This is the first of a two-part

series of articles on the behavior and design of steel support structures for pipes. This article

discusses the effects of ambient temperature changes, expansion joint requirements, and an

introduction to design loads. Part 2 concludes with the continuation of design loads, structure

stability concepts and detailing for stability requirements.It is common to overemphasize the

structural design of pipe support structures, rather than focus on detailing for stability or economics and

practical aspects of the steel structure and the foundations. This is sometimes referred to as "over-

designing" and "under-detailing". Sometimes the hanger-type pipe supports or the trapezes supported by

another structure, such as the main building frame, are referred to as "pipe support structures.

Frank E. Richart. Publication: Journal Proceedings. In these tests, major emphasis has

been placed on the combined column footing. Principal attention has been given to the resistance

of footings to failure by bond, diagonal tension and tension in the steel.

Taylor and francis.January 29, 2008 ; The principal features of the new edition is the

discussion of behavior of the steel structures and exemplify details of the design process.

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CHAPTER – 3

DESIGN PROCEDURE

3.1 CONVENTIONAL / CONTINUOUS PIPE RACK

Continuous Piperacks (conventional pipe rack) system: This is essentially a system where

multiple 2-dimensional (2D) frame assemblies (commonly called bents), comprised of two or

more columns with transverse beams, are tied together in the longitudinal direction utilizing

beam struts (for support of transverse pipe and raceway elements and for longitudinal stability of

the system) and vertical bracing to form a 3D space frame arrangement. Piperacks supporting

equipment such as air-cooled heat exchangers must utilize the continuous system approach.

3.1.1 Data collection for pipe rack design

Due to the “fast track” nature associated with most of the projects, often the final piping,

raceway, and equipment information is not available at initiation of the piperack design.

Therefore, as a Civil/Structural Engineer, you should coordinate with the Piping group,

Electrical, Control Systems, and Mechanical groups to obtain as much preliminary information

as possible. When received, all design information should be documented for future reference

and verification. In the initial design, the Engineer should use judgement when applying or

allowing for loads that are not known, justifying them in the design basis under "Design

Philosophy".

The following should be reviewed for design information:

• Plot plans and equipment location plans

• 3D model showing piping layout, cable tray layout, Piperack bent spacing and

elevation of support levels in the transverse direction , Elevation of longitudinal beam struts and

locations of vertical bracing. and location of pipe bridge, if any.

• Piping orthographic drawings.

• Vendor prints of equipment located on the rack, e.g., air coolers and exchangers.

The vendor prints should include the equipment layout, mounting locations and details, access

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and maintenance requirements, and the magnitude and direction of loads being transmitted to the

piperack.

• Electrical and control systems drawings showing the routing and location of

electrical and instrumentation raceways and/or supports.

• Underground drawings that show the locations of buried pipes,concrete structures

and foundations, duct banks, etc. in the area of the piperack.

• Pipe rack construction material (Steel, Cast-in-situ concrete, Pre-cast concrete)

shall be as per project design criteria.

Please note that, Unless specifically explained in the project design criteria, no allowance or

provisions should be made for future additions for pipe or raceway space and related loading.

3.1.2 Design loads consideration

Following loads are to be considered for the pipe rack design:

Piping Gravity load (D): In the absence of defined piping loads and locations, an assumed

minimum uniform pipe load of 2.0 kPa should be used for preliminary design of piperacks. This

corresponds to an equivalent load of 6 in (150 mm) lines full of water covered with 2 in (50 mm)

thick insulation, and spaced on 12 in (300 mm) centers. This assumption should be verified

based on coordination with the Piping Group, and concentrated loads should also be applied for

any anticipated large pipes. When the actual loads and locations become known, as the project

develops, the structural design should be checked against these assumed initial load parameters

and revised as required. A concentrated load should then be added for pipes that are 12 in (300

mm) and larger in diameter. The concentrated load P should be:

P =(W - s x p x d), s = Spacing of piperack bent, p = pipe weight considered (kPa), d = pipe

diameter W = pipe concentrated load.

Where consideration of uplift or system stability due to wind or seismic occurrences is required,

use 60% of the design gravity loads as an "all pipes empty" load condition.

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Loading due to hydrostatic testing of lines should be considered in the design if

applicable. Coordinate the testing plan(s) with Construction, Startup, and/or the Piping Group as

necessary, in order to fully understand how such loads will be applied to the piperack structure.

Under most normal conditions, multiple lines will not be simultaneously tested. The hydro-test

loads do not normally need to be considered concurrently with the other non-permanent loads,

such as live load, wind, earthquake, and thermal. Typical practice is to permit an overstress of

15% for the hydro-test condition. Because of these considerations, the hydro-test condition will

not normally govern except for very large diameter pipes.

Electrical Tray and Conduits (D): Electrical and control systems drawings and/or the

project 3D model should be reviewed to determine the approximate weight and location of

electrical trays, conduits, and instrumentation commodities. Unless the weight of the loaded

raceways can be defined, an assumed minimum uniform load of 1.0 kPa should be used for

single tier raceways.

Self weight of Pipe rack (D): The weight of all structural members, including

fireproofing, should be considered in the design of the piperack.

Weight of Equipment on pipe rack (D): Equipment weights, including erection, empty,

operating, and test (if the equipment is to be hydro-tested on the piperack) , should be obtained

from the vendor drawings. The equipment weight should include the dead weight of all

associated platforms, ladders, and walkways, as applicable. Special Loads: Special consideration

should be given to unusual loads, such aslarge valves, expansion loops, and unusual piping or

electrical configurations.

Live Load (L): Live load (L) on access platforms and walkways and on equipment

platforms should be considered, as applicable.

Wind Load (W): Transverse wind load on structural members, piping, electrical trays,

equipment, platforms, and ladders should be determined in accordance with project approved

design code. Longitudinal wind should typically be applied to structural framing, cable tray

vertical drop (if any), large dia pipes vertical drop (if any) and equipment only. The effects of

longitudinal wind on piping and trays running parallel to the wind direction should be neglected.

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Friction Loading (Tf): Friction forces caused by hot lines sliding across the pipe support

during startup and shutdown are assumed to be partially resisted through friction by nearby cold

lines. Therefore, in order to provide for a nominal unbalance of friction forces acting on a pipe

support, a resultant longitudinal friction force equal to 7.5% of the total pipe weight or 30% of

any one or more lines known to act simultaneously in the same direction, whichever is larger, is

assumed for piperack design. Friction between piping and supporting steel should not be relied

upon to resist wind or seismic loads.

Anchor and Guide Loads (Ta): Piperacks should be checked for anchor and guide loads

as determined by the Pipe Stress Group. It may be necessary to use horizontal bracing if large

anchor forces are encountered. For conventional pipe rack systems, it is normally preferred to

either have the anchors staggered along the piperack so that each support has only one or two

anchors, or to anchor most pipes on one braced support. For initial design, when anchor and

guide loads are not known, use a longitudinal anchor force of 5.0 kN acting at midspan of each

bent transverse beam (refer project design criteria). Guide loads are usually small and may be

ignored until they are defined by the Pipe Stress Engineer. For non-continuous pipe rack

systems, piping may be transversely guided or anchored at both cantilever frames and anchor

bays. Longitudinal anchors may be located only at anchor bays.

LOAD COMB 1 DL+WL(+X)

LOAD COMB 2 DL+WL(-X)

LOAD COMB 3 DL+WL(+Z)

LOAD COMB 4 DL+WL(-Z)

LOAD COMB 5 DL+LL

LOAD COMB 6 DL+LL+FLX+FLZ

LOAD COMB 7 DL+LL-FLX-FLZ

LOAD COMB 8 DL+LL-FLX+FLZ

LOAD COMB 9 DL+LL+FLX-FLZ

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********FOUNDATION DESIGN********

LOAD COMB 10 DL+LL+FLX+FLZ+WLX

LOAD COMB 11 DL+LL+FLX+FLZ-WLX

LOAD COMB 12 DL+LL+FLX+FLZ+WLZ

LOAD COMB 13 DL+LL+FLX+FLZ-WLZ

LOAD COMB 14 DL+LL-FLX-FLZ+WLX

LOAD COMB 15 DL+LL-FLX-FLZ-WLX

LOAD COMB 16 DL+LL-FLX-FLZ+WLZ

LOAD COMB 17 DL+LL-FLX-FLZ-WLZ

LOAD COMB 18 DL+LL-FLX+FLZ+WLX

LOAD COMB 19 DL+LL-FLX+FLZ-WLX

LOAD COMB 20 DL+LL-FLX+FLZ+WLZ

LOAD COMB 21 DL+LL-FLX+FLZ-WLZ

LOAD COMB 22 DL+LL+FLX-FLZ+WLX

LOAD COMB 23 DL+LL+FLX-FLZ-WLX

LOAD COMB 24 DL+LL+FLX-FLZ+WLZ

LOAD COMB 25 DL+LL+FLX-FLZ-WLZ

********FOR MEMBER DESIGN********

LOAD COMB 26 DL+LL+FLX+FLZ+WLX

LOAD COMB 27 DL+LL+FLX+FLZ-WLX

LOAD COMB 28 DL+LL+FLX+FLZ+WLZ

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LOAD COMB 29 DL+LL+FLX+FLZ-WLZ

LOAD COMB 30 DL+LL-FLX-FLZ+WLX

LOAD COMB 31 DL+LL-FLX-FLZ-WLX

LOAD COMB 32 DL+LL-FLX-FLZ+WLZ

LOAD COMB 33 DL+LL-FLX-FLZ-WLZ

LOAD COMB 34 DL+LL-FLX+FLZ+WLX

LOAD COMB 35 DL+LL-FLX+FLZ-WLX

LOAD COMB 36 DL+LL-FLX+FLZ+WLZ

LOAD COMB 37 DL+LL-FLX+FLZ-WLZ

LOAD COMB 38 DL+LL+FLX-FLZ+WLX

LOAD COMB 39 DL+LL+FLX-FLZ-WLX

LOAD COMB 40 DL+LL+FLX-FLZ+WLZ

LOAD COMB 41 DL+LL+FLX-FLZ-WLZ

Please note that, all friction forces and anchor forces with less magnitude, (say ~ 5.0 kN),

applied to the top flange of the beam, may be considered as resisted by the total beam section.

When anchor loads have large magnitude and are applied to the top flange of the beam, the effect

of torsion must be addressed. If the beam section is inadequate to take care of this torsional

force, alternatives to be considered, such as provide horizontal bracings at the load locations.

3.1.3 Load Combinations and allowable deflection of pipe rack

You need to create the load combinations per your project design criteria. However, I

have referred here some load combinations.

Please note the following:

• Earthquake load is a factored load.

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• For load combinations that include wind or earthquake loads, use only the non-

friction portion (anchor and guide portion) of the thermal loads, i.e., friction loads are not

combined with wind or seismic loads. Friction loads are considered to be self-relieving during

wind and earthquake and should only be combined with anchor and guide loads when wind or

earth-quake loads are not considered.

• Hydrostatic test loads need not be combined with wind and earthquake loads

unless there is a reasonable probability of the occurrence of either of these loads during

hydrostatic testing.

For calculation of foundation soil bearing pressures or pile loads, stability checks against

overturning, sliding, and buoyancy, and deflection checks, the following unfactored load

combinations (ACI 318) shall be used:

1. D

2. D + L + SL + Tf + Ta

3. D + Tf + Ta

4. D + 1.3W + Ta

5. D + L + 0.5SL + 1.3W +Ta

6. D + L + S +0.65W + Ta

7. 0.9De + 1.3W + Ta

8. D + E/1.4 + Ta

9. D + 0.2S + E/1.4 + Ta

10. 0.9De + E/1.4 + Ta

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Load Combinations for design of foundations

1. 1.4D

2. 1.4D + 1.7L +1.7S

3. 1.4D + 1.4Tf +1.4Ta

4. 0.75 (1.4D + 1.7L + 1.7S + 1.4Tf + 1.4Ta)

5. 0.75 (1.4D + 1.7L + 1.7S + 1.4Ta) + 1.6W

6. 1.2D + 0.2S + 1.0E + 1.2Ta

7. 0.9De + 1.6W + 1.2Ta

8. 0.9De + 1.0E + 1.2Ta

Steel Design load combinations

1. 1.4D

2. 1.2D + 1.6L + 0.5S + 1.2Tf + 1.2Ta

3. 1.2D + 1.6S + 0.5L + 1.2Tf + 1.2Ta

4. 1.2D + 1.6S + 0.8W + 1.2Ta

5. 1.2D + 1.6W + 0.5L + 0.5S + 1.2Ta

6. 1.2D + 1.0E + 0.5L + 0.2S + 1.2Ta

7. 0.9De + 1.6W + 1.2Ta

8. 0.9De + 1.0E + 1.2Ta

De is the minimum dead load on the structure.

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3.1.4 Final anchor and guide load check

Where the design of transverse beams has been based on anchor loads as explained in

design load consideration final check of beams (and other affected members) should be made

when final definition of these loads is available from the Pipe Stress Engineer. Based on the

Engineer's experience and judgement, an overstress in any element (of up to 10%) can be

considered, provided proper justification is given. Where such overstress cannot be properly

justified, modifications should be made to the piperack structure in order to bring the stress

levels within the normal allowables. Modifications could entail the addition of horizontal

bracing to the transverse beams to resist significant loads from the anchor(s), replacing and/or

adding members, strengthening members (i.e.,cover plating, etc.), and/or relocating the anchor

and guide load(s).

3.1.5 Allowable horizontal and vertical deflection

Allowable deflections of piperack structures shall be as per project design criteria.

However, you can consider the following as limit of deflection:Lateral deflection produced by

load combinations that include wind or seismic forces:Piperacks supporting equipment: h/100,

unless a more stringent requirement is given by the manufacturer of the equipment. Piperacks

supporting piping and raceway only: h/200 or as per project design criteria.Lateral deflection

produced by sustained static forces such as pipe and anchor loads: h/200 or as per project design

criteriaVertical deflection of beams due to gravity pipe loads:as per project design criteria h is

the total height of the pipe rack structure.

3.1.6Framing of continuous/conventional pipe rack

Frames

Main piperacks are usually designed as moment-resisting frames in the transverse

direction. In the longitudinal direction, there should be at least one continuous level of beam

struts on each side. For piperacks with more than one tier, the beam struts should be located at a

level that is usually equal to one-half tier spacing above or below the bottom tier. Vertical

bracing in the longitudinal direction should be provided to carry the longitudinal forces,

transmitted through the beam struts, to the baseplate / foundation level.

30

Transverse Beam

Transverse beams must be capable of resisting all forces, moments, and shears produced

by the load combinations. Transverse beams are generally a moment-resisting frame, modeled

and analyzed as part of the frame system. The analysis model must reflect the appropriate beam

end conditions. In the design of beams, consideration should be given to

• Large pipes that are to be hydro-tested.

• Anchor and friction load with large magnitude (see step-2, anchor and friction

load)

Central Spine

For steel piperacks with spans of more than 6 m, a center spine consisting of a system of

horizontal braces and struts located at midspan of each level of piping should be considered. This

additional light horizontal framing greatly increases the capacity of the transverse pipe support

beams to resist friction and anchor forces, and also serves to reduce the unbraced length of the

beam compression flange in flexure and to reduce the unbraced length of the beam about the

weak-axis in axial compression. This concept reduces the required beam sizes and provides a

mechanism for eliminating or minimizing design, fabrication, or field modifications that could

otherwise be required due to late receipt of unanticipated large pipe anchor forces.

Longitudinal Beam Strut

For typical continuous piperack systems, the longitudinal beam struts should be designed

as axially loaded members that are provided for longitudinal loads and stability. Additionally,

the longitudinal beam struts that support piping or raceway should be designed for 50% of the

gravity loading assumed for the transverse pipe or raceway support beams, unless unusual

loading is encountered. This 50% gravity loading will account for the usual piping and raceway

take-offs. Normally, the gravity loading carried by the beam struts should not be added to the

design loads for the columns or footings since pipes or raceway contributing to the load on the

beam struts would be relieving an equivalent load on the transverse beams.

31

For any continuous piperack system where the anticipated piping and raceway take-offs

are minimal or none, the 50% loading criteria does not apply. In such cases, the beam struts

should be designed primarily as axially loaded members. Do not provide beam struts if they are

not needed for piping or raceway support, or for system stability. Conversely, the 3D model

should be checked to verify that beam struts subjected to unusually large loads (such as at

expansion loops) have been given special consideration. All longitudinal beam struts, including

connections, should be designed to resist the axial loads produced by the longitudinal forces.

When designing the longitudinal beam struts for flexural loads, the full length of the

beam should be considered as the unbraced length for the compression flange.

Vertical Bracing

When moment-resisting frame design is not used in the longitudinal direction, vertical

bracing should be used to transmit the longitudinal forces from the beam struts to the

foundations. Knee-bracing or K-bracing is most often used for this purpose. Unless precluded by

equipment arrangement or interferences, bracing should be placed equidistant between two

expansion joints. Design calculations and drawings must reflect a break in the beam strut

continuity between adjacent braced sections through the use of slotted connections or by

eliminating the beam struts in the bays designated as free bays. The maximum length of a braced

section should be limited to 48m to 50m. If the braced bay is not located equidistant from the

free bays, the maximum distance from the braced bay to a free bay should be limited such that

the maximum total longitudinal growth or shrinkage of the unrestrained segment does not exceed

40 mm.

Column

The columns must be capable of resisting all loads, moments, and shears produced by the

load combinations.A moment-resisting frame analysis should normally be used to determine the

axial load, moment, and shear at points along the columns.The frame analysis model should be

based on the following:

• Consider column base as hinge.

• Use 4 bolt connections for safety purpose

32

For design of steel columns subjected to flexural loads, the distance between the base and

the first transverse beam or the knee brace intersection should be considered as the compression

flange unbraced length.

33

CHAPTER – 4

LOAD CALCULATION

4.1 PIPE LOAD

Load Calculation for 2", 6", 12" & 16" diameter pipe (Pipe weight + Pipe filled with oil)

As per the load data obtained from the piping input, the loads for the pipes are as

tabulated below:

Table-4.1 Load Calculation For Pipe Load

Pipe Dia

(inches)

No of

Pipes

Weight

of Pipe

(Kg/m)

Weight

of oil

(Kg/m)

Weight

of Pipe

x Nos

(Kg/m)

Weight

of water x

Nos

(Kg/m)

Weight of

water +

Weight of

Pipe

(Kg/m)

Total

weight

(kg/m)

2" 1 7.47 2.53 7.47 2.53 10.00 10

6" 2 42.50 17.50 85 35 60.00 120

12" 1 73.80 77.20 73.8 77.2 151.00 151

16" 4 93.10 146.90 372.4 587.6 240.00 960

216.87 244.13 538.67 702.33 461.00 1241.00

Total =

1241.00

Kg/m 12.4 KN/m

34

Fig 4.1 shows the pipe bridge is analysed using a structural software program staad pro. Analysis

has been carried out on the structural model considering all loads acting over the structure.

Analysed for various load combinations as per code.

35

Fig 4.2 The nodes numbers of the pipe rack

36

Fig 4.3 The beam numbers of the pipe rack

37

Fig 4.4 The top plan view of the pipe rack

Fig 4.5 The view of pipe rack

38

Fig 4.6 Shows the Grid 1 and Grid 2 of the pipe rack

39

Fig 4.7 The vertical pipe load of the pipe rack

40

4.2 WIND LOAD CALCULATIONS AS PER IS 875-3

Site wind speed, Vs = Vb x Sa x Sd x Ss x Sp

Site wind speed, Vs = Vb x Sa x Sd x Ss x Sp=33.5


Site wind speed, Vs = Vb x Sa x Sd x Ss x Sp=1+0.001*ΔS


Site wind speed, Vs = Vb x Sa x Sd x Ss x Sp=1

Site wind speed, Vs = Vb x Sa x Sd x Ss x Sp=1

Site wind speed, Vs = Vb x Sa x Sd x Ss x Sp= 1


Site wind speed, Vs = Vb x Sa x Sd x Ss x Sp

Effective height He=6.4

Terrain and building factor, Sb=1.6864

Effective wind speed, Ve = Vs x Sb=56.6497596

Dynamic pressure, qs

Dynamic pressure, qs = 0.613 x Ve^2=1.96723669605827

Size effect factor, Ca=0.94

Net pressure coefficient (Cp) is shown in the below sections=1

Width of the building, w=4.2

Height of building, h=8

Length of building, l=30.06

Wind Pressure, Pe = qs x Cp x Ca=1.85kN/sqm

41

4.2.1 Wind load calculation for the second frame in grid 1&2 - (X - Direction)

F= force acting in a direction specified

Cf = Force coefficient 1.7

Ae = Effective frontal area

Pd = Design wind pressure

Wind load applied over column as udl = 0.975 kN/m

Wind load applied over Beam 1 LVL as udl = 0.80 kN/m

Wind load applied over Beam 2 & 3 LVL as udl = 0.31 kN/m

Wind load applied over Bracing as nodal load (1B) = 0.81 kN

Wind load applied over Bracing as nodal load (2B) = 0.58 kN

Wind load for bracing applied as nodal load (2B) = 1.15 kN

Fig 4.8 The wind load applied on the grid 1 and 2

42

4.2.2 Wind Load applied in (Z - Direction) 90 Degree

Exposed Area for

Column = 0.32 x 8 x 3 = 7.68 Sqm

Beam (2-3) = 0.254 x 18.55 x 1 = 4.71 Sqm

Tie = 0.09 x 18.55 x1 = 1.67 Sqm

Truss = (0.09 x 3.06 x 8) + (.09*2*7) + (3.79*0.1*2) = 4.22 Sqm

24.42 Sqm

Total Area = 240.48 Sqm

Solidity Ratio Φ = Exposed area = 0.1015

Total Area Cf 1.9

Fig 4.9 The wind load applied in (Z-degree)

43

4.2.3 Wind load calculation for the frame in grid A - (Z - Direction)

Wind load applied over column = 1.090 kN/m

Wind load applied over Beam (1-2) as udl = 0.89 kN/m

Wind load applied over Tie = 0.35 kN/m

Wind load applied over Bracing as nodal load = 0.48 kN

Wind load for bracing applied as nodal load @ 2 points = 0.97 kN

Wind load for bracing applied as nodal load for stub = 0.35

kN

Fig 4.10 The wind load for the frame A in (Z-direction)

44

4.2.4 Wind load calculation for the second frame in grid B - (Z - Direction)

Wind load applied over column = 1.090 kN/m

Wind load applied over Beam (1-2) as udl = 0.89 kN/m

Wind load applied over Tie = 0.35 kN/m

Wind load applied over Bracing as nodal load = 0.48 kN

Wind load for bracing applied as nodal load @ 2 points = 0.97 kN

Wind load for bracing applied as nodal load for stub = 0.35 kN

Fig 4.11 The wind load for the frame B in (Z-direction)

45

Fig 4.12 Shear force diagram at (Z-direction)

Fig 4.13 Shear force diagram at (Y-direction)

46

Fig 4.14 Bending moment at (Z-direction)

Fig 4.15 Bending moment at (Y-direction)

47

CHAPTER – 5

DESIGN OF BASE PLATE

5.1 Loading

Maximum compression = 360.01 KN

Maximum tension = 187.67 KN

Base Plate details

Length L = 625

Width B = 450

Concrete

Grade of concrete fck = 35 N/mm2

Permissible stress in bending comp. = 11.5 N/mm2

Permissible bearing stress = 8.75 N/mm2 Ref:- 0.25fck

Permissible bond stress in tension = 2.37 N/mm2

modular ratio = 8.116

Bolt data

Dia of bolt Φ = 27 mm

Total no of bolts N = 4 nos

Permissible Axial Stress = 240 N/mm2

Permissible shear stress = 160 N/mm2

Check for compressive stress in concrete

Σc= P/(LxB)

= 360.008x1000/(625x450)

= 1.920042667 < 8.75

SAFE

48

5.2 Design for tension

Maximum tension = 187.671 KN

No of bolts taking tension = 4

Tension per bolt = 70.376625 KN

Design moment M = WL/4

= 70.38x0.225/4

= 3.96 KNm

Allowable bending stress σbc = 165 N/mm2

treq = 6M/(bxσbc)

= (6x3.96x1000000)/(150x165)

= 27.06193215 mm

5.3 Design for compression

Maximum compression P = 360.008 KN

Base pressure = P/A

= 1.92 N/mm2

49

Design bending moment M = wL2/8

= 12150.27 Nmm/mm

treq = 6M/(bxσbc)

= (6x12150.27)/(1x165)

= 21.01970504 mm

Provide 30mm thick base plate.

5.4 Design of bolts subjected to shear and tension

Input :

Actual tension in bolts T = 187.67 kN

Actual shear in bolts Fx = 46.073 kN

Fz = 68.352 kN

V = 82.43 kN

Number of bolts resisting tension Nt = 4

Number of bolts resisting shear Ns = 4

Actual tension/bolt =187.67/4 = 56.30 kN

Actual shear/bolt =82.43/4 = 30.91 kN

Diameter of bolt D = 27 mm

Number of bolts provided n = 4

Permissible tensile stress stf = 240 N/mm2

Permissible shear stress tvf = 160 N/mm2

5.5 Calculations

Actual tensile stress = T/(n*PI()*D^2/4*0.8)

Only 80% of the bolt area taken on conservative side

50

stf,cal =56.3x1000(3.14/4x20^2x0.8) = 122.9 N/mm2

Actual shear stress= V/(n*PI()*D^2/4*0.8)

tvf,cal =30.91x1000/(3.14*27^2/4x0.8) = 67.5 N/mm2

Combined stress ratio= stf,cal/stf+ tvf,cal/tvf = 122.9/(240)+67.5/(160)

= 0.93

Allowable stress ratio = 1.4 SAFE

Calculation of embedment length :

Grade of concrete fck = 35 N/mm2

Permissible bond stress tbd = 0.4√fcu N/mm2

= 2.37 N/mm2

Referring clause 3.12.8.4 of BS 8110-1

Tension per bolt, Tb = = 56.30 kN

Embedment length req =Tb/(tbd*PI()*D*0.8) = 56.3*1000/(2.37*3.14*27*0.8)

= 351 mm

Embedment length provided = 351 mm

51

CHAPTER – 6

DESIGN OF PEDESTAL

6.1 Pedestal Mark

B

x

D

Design data

Column Size

Width, B = 600 mm

Depth, D = 775 mm

cover = 40 mm

Assuming dia of bar = 16 mm

Assuming dia of link = 8 mm

fcu = 35 N/Sqmm

fy = 460 N/Sqmm

b' = 544 mm

d' = 719 mm

b' / B = = 0.907

d' / D = 0.928

52

Effective length calculation

Unsupported length, about depth = 1.80 m

Unsupported length, about width = 1.80 m

Effective length factor about depth = 2

Effective length factor about width = 2

Effective length of column about depth, Lex 2*1.8 = 3.60 m

Effective length of column about width, Lez 2*1.8 = 3.60 m

Forces on columns

Refer staad output of member end forces

Axial load on column, N = 360.01 kN

Force, Fx = 46.03 kN

Force, Fz = 68.35 kN

Moment about depth

Initial end moment, M2x = 123.03 kNm

Smaller initial end moment, M1x = 0.00 kNm

Moment about width

Initial end moment, M2z = 82.86 kNm

Smaller initial end moment, M1z = 0.00 kNm

Slenderness check

Slenderness about depth, Lex / D = 4.65

Slenderness about width, Lez / B = 6.00

53

6.2 Calculation of Nuz and K

Balance load, Nb = 0.25 x fcu x B x D = 4068.75 kN

Assuming ptmin = 0.4%, Asc = 0.4 x B x D / 100 = 1860 Sq

Nuz, (0.45 x fcu x Ac) +(0.95 x Asc x fy) 8136.57 kN

Reduction factor , K = (Nuz - N)/ (Nuz- Nb) = 1.912

Hence K is limited to one K = 1 (As per Cl 3.8.3.1 of BS 8110:Part 1:1997) 1

Additional moments

About major axis = aux, K x D x (Lex/D )^2/20000.00 mm

Max = N*aux = 0.00 kNm

Mx = M2x + Max = 123.03 kNm

About minor axis = auz = K x B x (Lez/B )^2/2000 0.00 mm

Maz = N*auz = 0.00 kNm

Mz = M2z + Maz = 82.86 kNm

Ratio = N / (B x D x Fcu) = 0.022

(As per Table 3.22 of BS 8110:Part 1:1997)

Co-efficient Beta, β = 0.973455631

Mx / d' = 171117.7

Mz / b' = 152311.8

As Mx / d' >Mz/b'

Mx' = Mx + Mz x β x d' / b' = 229.64 kNm

54

6.3 Section design - Ratios for chart entry

Axial load ratio =Nratio = N / (B x D) = 0.77

For design we have considered Maximum Moment about one axis

Mz ratio = Mz' / (B x D^2) = 0.64

d'/D = 0.93

Actual Steel Percentage required, P(req) = 0.80 %

Area of Reinforcement required Ast(reqd) = 3720 Sqmm

Area of Reinfocementrequired Ast reqd. (for each face) = 1860 Sqmm

Since Limit state stress in reinforcing steel is taken as 0.87fy in charts

as against 0.95fy inEquation 1 of cl. 3.4.4.5,the modification in

reinforcement area calculation is taken as below

Actual Ast reqd. = 1860*0.87/0.95 =1703 Sqmm

Total area of Reinforcement = 3407 Sqmm

Total area of Reinforcement Provided

Provide 6 nos of 20 dia bars = 3768 Sqmm

6 nos of 20 dia bars Hence o.k

Ast provided in each faces 6 -16 + 6 -16 dia bars. = 3768 Sqmm

55

CHAPTER – 7

Design of Combined Foundation

7.1 Design of Combined Foundation "F1"

LC 30

Net SBC SBCnet 106.25 kN/m2

Factor for inc in BC Fbc 1

Joint No 5 7

X

PEDESTAL MARK

Col Mark SUM 1 2 cx1

Z wrt 1 0 4.2 z z b

X wrt 1 0 0 cx2

P (kN) -84.64 360.01 Cz1 x Cz2

Mx (kNm) 0 0.00 0.00

Hz (kN) -129.053 -60.70 -68.35

Mz (kNm) 0 0.00 0.00

Hx (kN) 55.364 27.61 27.75

Pedestal Size

lZ 0.6 0.6

lX 0.775 0.78

Pped 11.04 11.04

Depth of foundation from the level of point of application of forces

dforc 1.3 1.3

56

Depth of foundation below ground level (FGL)

Depth of foundation below Natural Ground Level (NGL)

Unit Weight of soil

Projections of Footing (from centreline of column)

LHS Cz1 1.725

RHS Cz2 1.725

Bottom Cx1 1

Top Cx2 1

Length of footing l 7.650 m

Width of footing b 2.000 m

Depth of footing d 0.350 m

Calculations

Col Mark SUM 1 2

xcor 1.725 5.925

ycor 1 1

Axial Load including weight of Pedestal

( Pconc = P + Pped )

Pconc 297 -73.59 371.05

Moment at base of foundation due to Horizontal Forces

(Mxh = Hz * dforc ) (Mzh = Hx * dforc )

Mxh -167.7689 -78.9113 -88.8576

Mzh 71.97 35.8943 36.0789

Moments due to Conc. Moments & Horizontal Forces

(Myc = My + Myh ) (Mxc = Mx + Mxh )

57

Mxc -168 -78.9113 -88.8576

Mzc 72 35.8943 36.0789

Gross SBC SBCg= Fbc * SBCnet + gs * dfngl= 125.25 kN/m2 126kN/m2

Total Axial Load inclwt of pedestal (∑Pconc ) ∑P 297.4595 kN

Area of foundation ( Provided ) A l * b 15.3 m2

Load due to soil Psoil gs*(df - d)*(A - S(lx*ly)) 177.47 kN

Weight of foundation Fbase A*d*25 133.875 kN

Total Vertical Load Pv SP + Psoil + Fbase 608.80 kN

CG of load system from bottom left corner of footing

Moments due to ∑concS(∑conc Xcor) 2071.534988

S(Pconc Zcor) 297.4595

External Moments ∑Mxm 0 ∑Mzm 0

Moment due to Horizontal Forces ∑Mxh 167.7689 ∑Mzh 71.97

Moment due to Soil & Raft(Psoil+Fbase)*l/2 1190.89 (Psoil+Fbase)*b/2

311.3445

0

Total Moment ∑Mx 3430.20 ∑Mz 680.7772

Horizontal Forces ∑Hz -129.053 ∑Hx 55.364

7.1.1 Longitudinal direction ( Z - dir )

zcgcor SMx / Pv 5.634

Eccentricity along Z Dir from CG of Raft ex zcgcor-l/2 1.809

ez 1.809 > l / 6 1.275

58

7.1.2 Transverse direction ( X - dir )

CG from bottom edge xcgcor SMz / Pv 1.118

Eccentricity along X Dir from CG of Raft ex ycgcor-b/2 0.118

ex 0.118 < b / 6 0.333

ez / l 0.237 m

ex / b 0.059 m

Mx = Pv * ez

=608.8*1.81 = 1101.52 kNm

Mz =Pv * ex

=608.8*0.12 = 71.97 kNm

fmax Pv/A + 6*Mx/(b*l^2) + 6*Mz/(l*b^2)

= 608.8/15.3+6*1101.52/(2*7.65^2)+6*71.97/(7.65*2^2)

fmax 110.37 kN/m2 < Gross SBC 126 Safe

fmin 608.8/15.3-6*1101.52/(2*7.65^2)-6*71.97/(7.65*2^2)

fmin -30.79 kN/m2 LOC 21.811 %

Redistributed Pressure

ez / l = 0.237

ex / b = 0.059

From Tengs Chart Coeff (K) = 3.027

59

Max P= KQ/BL =3.02694942934839 X 608.804 / 7.65 X 2

= 120.4456811 OK

Design Pressure

Along Z - Direction

fzmax =Pv/A*(1+6*ABS(ez/l)) =608.8/15.3x(1+6x0.237)

fzmax 100.678 kN/m2 220.7401143

fzmin =Pv/A*(1-6*ABS(ez/l)) = 608.8/15.3x(1-6x0.237) -61.57566987

fzmin 0.000 kN/m2

Along X - Direction

fxmax =Pv/A*(1+6*ABS(ex/b)) =608.8/15.3x(1+6x0.059)

fxmax 53.90 kN/m2

fxmin =Pv/A*(1-6*ABS(ex/b)) =608.8/15.3x(1-6x0.059)

fxmin 25.68 kN/m2

7.1.3 Pressure Along Z - Direction

LHS fzl 0.00 kN/m2

RHS fzr 100.68 kN/m2

Pressure Along X - Direction

Top fxt 53.90 kN/m2

Bottom fxb 25.68 kN/m2

60

Check For Overturning

R.M O.M

3262.43 Mx 167.7689 Mx

608.804 Mz 71.9732 Mz

Along X 19.45 Ok

Along Z 8.46 Ok

Check For Sliding

Restoring Force= 243.5216 KN

Sliding Force

55.364 Along X 4.398555018 Ok

129.053Along Z 1.886989067 Ok

61

7.1.4 Load calculations for combined Footing “F1”

Length of the footing = 7650 mm

Breadth of the footing b = 2000 mm

Depth of the footing D = 350 mm

Pressure from analysis

qmax = 110.37 kN/m²

qmin = -30.79 kN/m²

Uniformly distributed load

Self wt. of Fdn. 2.0 x 0.35 x 25 = 17.500 kN/m

Wt. of soil filling = 23.20 kN/m

Total = 40.699 kN/m

62

Total downward force

40.699 x 7.7 + 0.00 + 0.00 311.345 kN

Max B.M= 160 kNm 152.817

Max S.F= 180 kN 174.061

SF

Design of Footing - X Direction ( Designed as cantilever)

63

Basic Data:

Concrete grade M30 fck = 30 N/mm²

Steel grade Fe415 fy = 415 N/mm²

Load factor ld= 1.5

Section Data:

Projection of footing from col. face l = 1000 mm



Clear cover to reinf. d' = 75 mm

Dia of bar used f = 12 mm

Load data:

Maximum pressure fmax= 53.90 kN/m2

Maximum Bending Moment M = 26.95 kN-m

Total moment M = 26.95 kN-m

Reinforcement:

Factored Bending Moment Mu = 40.43 kN-m

Eff. depth of footing d =350 - 75 - 12/2 = 269mm

Mu/bd² = 40.43x 10^6/(1000 x 269²) = 0.559

% of Reinforcement required ptr = 0.16

Minimum % of steel required pmin = 0.13

\ pt = 0.16

Area of steel required Ast = 425.6 mm²/m

Required spacing 12mm dia bars @ 266 mm c/c

64

Provide 12mm dia bars @ 200 mm c/c

Provided Area of steel Astp = 565.5 mm²/m

7.1.5 Design of Strap Beam

Dimensions

B= 600 mm

D= 750 mm

fck= 30 N/mm2

fy= 415 N/mm2

Maximum Bending moment KN-M = 160.00

Factored Bending Moment, Mu KN-M = 240.00

Effective depth of footing, d = 665.00

Shear Force V KN = 180.00

Factored Shear Force, Fu KN = 270.00

Mu/bd2, R = 0.90

% of reinforcement required (Refer BS8110-3 1985 Chart no 9 : pg 17)

= 0.25

Min .% of reinforcement required = 0.20

Cover = 75.00

Dia of bar = 20.00

Area of cross section of bar = 314.29

Area of steel required ,As = 999.67

Provide number of bar dia required = 4.18

Hence, number of dia of bar provided = 6

Area of steel provided, As = 1885.71 0.47

65

7.1.6 Check For Shear


Nominal shear stress, tv N/mm2 = 0.68

B = 7.370365484

Allowable Shear Stress = 0.4852 N/mm2

Provide shear reinforcement Vu - = 76.42

2 LeggedProvide 10mm bar at = 200.00

Provide 10 mm @ 200.00 mm c/c

66

7.2 Design of Combined Foundation "F2"

Load Case LC 22

Net SBC SBCnet 106.25 kN/m2

Factor for inc in BC Fbc 1

Joint No 9 11

PEDESTAL MARK

Col Mark SUM 1 2

Z wrt 1 0 4.2

X wrt 1 0 0

P (kN) -30.26 295.35

Mx (kNm) 0 0.00 0.00

Hz (kN) -96.994 48.41 -48.59

Mz (kNm) 0 0.00 0.00

Hx (kN) -55.795 -27.55 -28.25

Pedestal Size

lZ 0.6 0.6

lX 0.775 0.775

Pped 16.86 16.86

Depth of foundation from the level of point of application of forces

dforce 1.8 1.8

Depth of foundation below ground level (FGL)

Depth of foundation below Natural Ground Level (NGL)

Unit Weight of soil

67

Projections of Footing (from centreline of column)

LHS Cz1 0.9

RHS Cz2 0.9

Bottom Cx1 1.25

Top Cx2 1.25

Length of footing l 6.000 m

Width of footing b 2.500 m

Depth of footing d 0.350 m

Calculations :

Col Mark SUM 1 2

xcor 0.9 5.1

ycor 1.25 1.25

Axial Load including weight of Pedestal

Pconc 299 -13.41 312.21

Moment at base of foundation due to Horizontal Forces

Mxh -174.5892 -87.1344 -87.4548

Mzh -100.43 -49.581 -50.85

Moments due to Conc. Moments& Horizontal Forces(Myc = My + Myh ) (Mxc = Mx + Mxh )

Mxc -175 -87.1344 -87.4548

Mzc -100 -49.581 -50.85

Gross SBC SBCg= Fbc * SBCnet + gs * dfngl= 134.75 kN/m2 135 kN/m2

68

Total Axial Load incl wt of pedestal ( ∑Pconc ) ∑P 298.8005 kN

Area of foundation ( Provided ) A l * b 15 m2

Load due to soil Psoil gs*(df - d)*(A - ∑(lx*ly)) 307.43 kN

Weight of foundation Fbase A*d*25 131.25 kN

Total Vertical Load Pv ∑P + Psoil + Fbase 737.48 kN

CG of load system from bottom left corner of footing

Moments due to Pconc ∑ (Pconc Xcor) 1580.1909 ∑(Pconc Zcor) 373.500625

External Moments ∑Mxm ∑Mzm 0

Moment due to Horizontal Forces ∑Mxh 174.5892 ∑Mzh -100.43

Moment due to Soil & Raft ∑ (Psoil+Fbase)*l/2 1316.04(Psoil+Fbase)*b/2 548.349375

0

Total Moment ∑Mx 3070.82 ∑Mz 821.419

Horizontal Forces ∑Hz -96.994 ∑Hx -55.795




7.2.1 Longitudinal direction ( Z - dir )

zcgcor SMx / Pv 4.164

Eccentricity along Z Dir from CG of Raft ex zcgcor-l/2

ez 1.164 > l / 6 1.000

69

7.2.2 Transverse direction ( X - dir )

CG from bottom edge xcgcor ∑Mz / Pv 1.114

Eccentricity along X Dir from CG of Raft ex ycgcor-b/2 0.136

ex 0.136 < b / 6 0.417

ez / l 0.194 m

ex / b 0.054 m

Mx = Pv * ez

=737.48*1.16 = 858.38 kNm

Mz =Pv * ex

=737.48*0.14 = 100.43 kNm

fmax Pv/A + 6*Mx/(b*l^2) + 6*Mz/(l*b^2)

= 737.48/15+6*858.38/(2.5*6^2)+6*100.43/(6*2.5^2)

fmax 122.46 kN/m2 < Gross SBC 135 Safe

fmin 737.48/15-6*858.38/(2.5*6^2)-6*100.43/(6*2.5^2)

fmin -24.13 kN/m2 LOC 16.460 %

Redistributed Pressure

ez / l = 0.194

ex / b = 0.054

From Tengs Chart Coeff (K= 2.56794252 2.5767

70

Max P= KQ/BL = 2.56794251983484 X 737.48 / 6 X

= 126.25375 OK

Design Pressure

Along Z - Direction

fzmax =Pv/A*(1+6*ABS(ez/l)) =737.5/15x(1+6x0.194)

fzmax 107.110 kN/m2 244.9190667

fzmin =Pv/A*(1-6*ABS(ez/l)) =737.5/15x(1-6x0.194)

-48.25773333

fzmin 0.000 kN/m2

Along X - Direction

fxmax =Pv/A*(1+6*ABS(ex/b)) =737.5/15x(1+6x0.054)

fxmax 65.23 kN/m2

fxmin =Pv/A*(1-6*ABS(ex/b)) =737.5/15x(1-6x0.054)

fxmin 33.10 kN/m2

7.2.3 Pressure Along Z - Direction

LHS fzl 0.00 kN/m2

RHS fzr 107.11 kN/m2

Pressure Along X - Direction

Top fxt 33.10 kN/m2

Bottom fxb 65.23 kN/m2

71

Check For Overturning

R.M O.M

2896.23 Mx 174.5892 Mx

921.85 Mz 100.431 Mz

Along X 16.59 Ok

Along Z 9.18 Ok

Check For Sliding

Restoring Force= 294.992 KN

Sliding Force

55.795 Along X 5.287068734 Ok

96.994 Along Z 3.041342763 Ok

Load calculations for combined Footing

Length of the footing l = 6000 mm



Pressure from analysis

qmax = 122.46 kN/m²

qmin = -24.13 kN/m²

72

7.2.4 Load calculations for combined Footing “F2”

Uniformly distributed load

Self wt. of Fdn. 2.5 x 0.35 x 25 = 21.875 kN/m

Wt. of soil filling 51.24 kN/m

Total 73.113 kN/m

73.113 kN/m

Total downward force

73.113 x 6.0 + 0.00 + 0.00 438.680 kN

BM

73

Max B.M= 130 kNm 126.595

Max S.F= 150 kN 149.884

SF

Design of Footing - Z Direction ( Designed as cantilever)

Basic Data:

Concrete grade M30 fck = 30 N/mm²

Steel grade Fe415 fy = 415 N/mm²

Load factor ld= 1.5

Section Data:

Projection of footing from col. face l= 1250 mm

Breadth of the footing b= 1000 mm

Depth of the footing D= 350 mm

Clear cover to reinf. d'= 75 mm

Dia of bar used f = 12 mm

74

Load data:

Maximum pressure fmax= 65.23 kN/m2

Maximum Bending Moment M = 50.96 kN-m

Total moment M = 50.96 kN-m

Reinforcement:

Factored Bending Moment Mu = 76.45 kN-m

Eff. depth of footing d =350 - 75 - 12/2 =269mm

Mu/bd² = 76.45x 10^6/(1000 x 269²) =1.056

% of Reinforcement required ptr = 0.31

Minimum % of steel required pmin = 0.13

\ pt = 0.31

Area of steel required Ast = 821.8 mm²/m

Required spacing 12mm dia bars @ 138 mm c/c

Provide 12mm dia bars @125 mm c/c

Provided Area of steel Astp = 904.8 mm²/m

0 126.25375

2.5 8.01

85.45932963

98.18245899

75

Moment =41.90260613-11.38176563 =30.52084051

M/bd2 =0.632678663

Pt = 0.18 0.31

Ast = 821.8482124

Spacing = 137.5436465

Shear Soil

Vu= 66.60144501 18.1611 48.44034501

Tv= 0.270113448

B= 11.40125568

Tc= 0.40274325 OK

7.2.5 Design of Strap Beam

Dimensions

B= 600 mm

D= 750 mm

Fck= 30 N/mm2

fy= 415 N/mm2

Maximum Bending moment KN-M = 130.00

Factored Bending Moment, Mu KN-M = 195.00

Effective depth of footing, d = 665.00

Shear Force V KN = 150.00


Mu/bd2, R = 0.73

% of reinforcement required= 0.20

Min .%of reinforcement required = 0.20

Cover = 75.00

76

Dia of bar = 20.00

Area of cross section of bar = 314.29

Area of steel required ,As = 812.22

Provide number of bar dia required = 3.58

Hence, number of dia of bar provided = 6

Area of steel provided, As = 1885.71 0.47

7.2.6 Check For Shear


Nominal shear stress, tv N/mm2 = 0.56

B = 7.370365484

Allowable Shear Stress = 0.4852 N/mm2

Provide shear reinforcement Vu - = 31.42

2 Legged Provide 10mm bar at = 200.00

Provide 10 mm @ 200.00 mm c/c

77

CHAPTER – 8

CONCLUSION

Pipe racks or pipe supports are considered as one of the most important parts in a refinery

which need to be constructed with precision. As supports of refinery pipes, such elements are

installed numerously, to carry pipes with different size and diameters. The accessories increase

the cost of the concrete pipe rack, therefore it shall be reduced to minimum. It is obvious that the

use of anchoring rail will make it easy to fix apparatus or secondary frame. In majority of

refineries, pipe rack systems are made of steel, and thus from the construction point of view, it is

considered a simple job with no difficulty. Overall pipe rack design must meet the current needs

of a client as well as any expansion plans without making major modifications to existing

facilities. Available space in the pipe rack must be considered valuable and used to the utmost

advantage of present and future needs.

78

REFERENCE

DESIGN BOOKS REFERED

1. Sadhu Singh (1990),Strength of Materials,6th

edition, Laxmi publications(P)ltd, India ,pp

287.

2. N. Krishna Raju (1987),Reinforced concrete structures,4th edition, Khanna publishers,

delhi, India ,pp 189-196.

3. Ramachandran(2006), D.S.S, Rajinder kumar jain publications, tenth edition, pp238-267.

CODE BOOKS REFERED

1. IS: 456-2000,“ Indian standard code of practice for Plain and Reinforced concrete”,

fourth revision.

2. IS: 800-2007, “Indian standard code of practice for general construction in steel”, third

revision.

3. IS: 875 Part 1, “Indian standard code of practice for Unit weights of materials”.

4. IS: 875-1987, “Design loads (other than earthquake) for buildings and structures” ,Part

3”Wind Loads.

5. IS: 1498-1970, “Classification and identification of soils for general engineering

purposes” (First Revision).

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