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The Role of National BIM Standard in Structural Design
Nawari O. Nawari
1
and Marcello Sgambelluri
2
1 Nawari O. Nawari, Ph.D., P.E., M.ASCE, School of Architecture, University of
Florida, Gainesville, FL 32611-5702, Email: [email protected]
Marcello Sgambelluri, P.E., M.ASCE, John A. Martin & Associates, Inc.
Abstract
All the different entities utilizing BIM technology in the construction and building
industry including architects, engineers, contractors, and software developers, have
diverse nomenclatures, diverse vocabularies, geometries, computing paradigms, dataformats, data schemas, scales and fundamental world-views. They also have different
requirements for accuracy, verisimilitude, and rendering performance. These various
organizations have different standards and business processes for which they havedeveloped their own paper and digital delivery procedures. To solve these problems,
The National BIM standard (NBIMS) establishes standard definitions for building
information exchanges to support critical business contexts using standard semantics
and ontologies. This Standard forms the foundation for accurate and efficientcommunication and commerce that are needed by the construction industry. This
paper investigates the general objectives of this standard, its relationship to structural
engineering practice and focuses on the importance of involvement and contribution
of structural engineering community to this standard. The standard is still in itsinfancy and the evolution and maturity of NBIMS will help to establish advanced
design, communication and simulation tools that give the structural engineeringcommunity an opportunity to change the way it works in the industry, including open
collaboration between stakeholders, design for optimum structure, increased energy
efficiency, flexibility, constructability, comfort, and sustainability. It is important to
note that agencies in the government and private sectors are currently adopting andenforcing the NBIM standard and it is becoming critical that the structural
engineering community understands and delivers projects consistent with these
NBIMS standards.
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Architects and engineers, as well as the real estate appraiser or insurer must be able tospeak the same language and refer to items in the same terms as the first responder in
an emergency situation. This also carries to the world view of being able to translate
to other international languages in order to support the multinational corporation. Inorder to standardize these many options and produce a comprehensive viable
Standard, all organizations have to be represented and solicited for input.
Figure 1. Relationship of NBIMS to the international Dictionary (NBIMS
version Part 1, 2007).
FUNDAMENTALS
One of the primary roles of NBIMS is to set the ontology and associated commonlanguage that will allow information to be machine readable between team members
and eventually provide direction and, add quality control to what is produced and
called a BIM. Ultimately, these boundaries will encompass everyone who interactswith the built and natural environments. In order for this to occur, the team members
who share information must be able to map to the same terminology. Commonontologies will allow this communication to occur.
The NBIM Standard Version 1 Part 1 defines a minimum standard fortraditional vertical construction (e.g. office buildings). It is assumed that developing
information exchange standards will grow from this minimum requirement. The
Standard also proposes a Capability Maturity Model (CMM) for use in measuring thedegree to which a Building Information Model implements a mature BIM standard.
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The CMM scores a complete range of opportunity for BIMs, extending from a pointbelow which one could say the data set being considered is not a BIM to a fully
realized open and interoperable lifecycle BIM resource.
The USACE BIM Roadmap is presented as a useful reference for buildingowners seeking guidance on identifying and specifying data to include in a BIM
from a design or construction perspective.The core components of NBIMS (see figure 2) include the InformationExchange Template, BIM Exchange Database, the Information Delivery Manual
(IDM), and Model View Definition (MVD).
Figure 2. NBIMS main Components
The Information Exchange Template and BIM Exchange Database are web based
tools to provide search, discovery, and selection of defined exchanges as well as a
method of providing initial information necessary to propose and begin a new
exchange definition.The Information Delivery Manual IDM, is adapted from international
practices, to facilitate identification and documentation of information exchange
processes and requirements. IDM is the user-facing phase of NBIMS exchangestandard development with results typically expressed in human-readable form.
The Model View Definition (MVD) is the software developer interface ofexchange. MVD is conceptually the process which integrates ExchangeRequirements (ER) coming from many IDM processes to the most logical Model
Views that will be supported by software applications (see Figure 3). Implementation
of these components will specify structure and format for data to be exchanged using
a specific version of the Industry Foundation Classes (IFC) standard to create andsustain a BIM application.
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Figure 3. National BIM Standard Exchange Tier Schema
WHO SHOULD USE NBIMS AND WHY?
Figure 4 below illustrates the data exchange workflow in a typical AEC projectutilizing NBIMS. Owners will use it to gain an understanding of what is possible
from using BIM based on NBIMS Initiative concepts and the NBIM Standard.
Practitioners will use it to understand the details associated with their design and BIMconcepts. Product manufacturers will use it to prepare and position their products toadd new value. Software vendors will use it to know how to further incorporate BIM
capabilities into their software products. Others involved with facility information
will be able to use NBIMS to access information that will support their variousendeavors.
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Figure 4. National BIM Standard definition
NBIM STANDARD AND STRUCTURAL ENGINEERING
To explain the role of NBIM Standard in structural engineering, it is essential todevelop a consistent vocabulary and set of definitions as a basis for the discussion.
Definitions used in this standard are presented to promote understanding in a nar-
rative fashion and in a manner such that they build upon and support one another inthe description of NBIM Standard:
A Building Information Model is a digital representation of the physical and
the functional characteristics of a facility. As such it serves as a shared knowledge
resource for information about a facility, forming a reliable basis for decisions duringits life cycle from inception onward.
Building Information Modeling is the human activity of using BIM software
and other related software, hardware and technologies to create and use in a buildinginformation model.
Parameter is a quantity that is constant under a given set of conditions (rule
set), but may be different under other conditions. For example: a duct penetrates a
non-rated steel stud and gypsum board wall, and the annular space of the penetrationis sealed only with caulk. If you change the wall to a 2-hour rated concrete fire barrier
(new parameter) the duct still penetrates the wall, but in a different way.
Objects represents not only the geometry required to represent the componentor assembly graphically (visually) but also has the ability to have much more
information about that object associated with it or related to other intelligent objects
associated with it. The geometric parameters of an object are only one of many fields
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in a database that describes the visual features and characteristics of the object. Otherparameters might include variables such as how the object may change when
something with which it is associated changes. For example, if a relationship is
established between a column and a beam that are connected in the model andassigned a specified connectors and the modeler (engineer, designer, etc.) decides to
change the specified connections from simple to moment connection sizes ofconnectors automatically are adjusted to accommodate the new specification, andforce distribution between the connected members will be updated at the same time.
Parametric is a rule based relationships between objects that enable related
properties to be updated when one property changes.
Industry Foundation Classes (IFC), and the International Alliance forInteroperability (IAI) define the virtual representations of objects used in the capital
facilities industry, their attributes, and their relationships and inheritances. Properly
implemented, they are the mechanism which makes Building Information Modeling(BIM) interoperable among the software applications that currently support IFC
worldwide. IFC are the foundation for the open standards approach to BIM. While
IFC may be the single most important ingredient for the success of BIM, they aretransparent to the user - the user does not need to be aware of how they are used in
software.
IFC are at the heart of the BIM concept and are a foundation element within
the open standards approach to NBIMS. The reliance on an open standards approachwill ensure that all information is sustainable throughout the long life of a facility.
NBIMS is using the IFC data model of buildings as the data model for
encoding information exchange because it constitutes an interoperability-enablingtechnology that is open, freely vailable, non-proprietary and extensible.
OmniClass is designed to provide a standardized basis for classifyinginformation created and used by the North American architectural, engineering, and
construction (AEC) industry, throughout the full facility lifecycle from conception to
demolition or reuse, and encompassing all of the different types of constructionprojects that make up the capital facilities industry throughout the facility lifecycle. It
is anticipated that all OmniClass tables will have application in the ordering of BIM
information in the National BIM Standard, though some may be more central to theprocess of organizing information for exchange throughout the facility lifecycle than
others.
From these definitions, it is clear that the main role of NBIM standard in
structural engineering is the specifications of structural objects, their parametricrequirements and model view definition (MVD).
Figure 5. NBIM Standard Development Process (NBIMS, 2007)
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The aim of the Information Delivery Manual (IDM) and Model ViewDefinition (MVD) is to specify exactly which information is to be exchanged in each
exchange scenario and how to relate it to the IFC model. For example, an architect
designing a building needs to be sure that she receive information from the structuralengineer about which walls and columns are load bearing and which are not. At the
same time, the structural engineer needs to know the function of each of the spaces inthe building in order to calculate the right design loads for the structure. IDM alongwith MVD explains the exchange scenario in plain text for human readability and in a
technical way to enable implementation of automatic checks and validations in
applications. Continuing the example above, the engineer can run a quick test through
a computer based on the requirements established in the IDM/MVD to verify that thearchitect has sent enough information to get started on the work.
Capability Maturity Model (CMM): The NBIMS version 1 (Overview,
Principles, and Methodologies) is intended to serve as a guide for informationgeneration and management between all phases of a facilitys life cycle. In Chapter
4.1, there exists a definition for the minimum standard providing a baseline for
measuring information exchange capabilities within a given BIM, the so calledCapability Maturity Model (CMM). The CMM is a matrix with 11 area of interest on
the x-axis and 10 levels of maturity on the y-axis. Areas of interest include; data
richness, life-cycle views, change management (formerly ITIL maturity assessment),
roles or disciplines, business processes, timeliness/response, delivery method,graphical information, spatial capability, information accuracy, and
interoperability/IFC support. Ratings for maturity levels are on a scale of 1 to 10,
with 10 being the most mature (see figure 3).
Figure 6. CMM Areas of Interest and Their Respective Credits (NBIMS, 2007)
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From structural engineering stand point, at this stage of BIM maturity the mostcritical component is data richness. The NBIM Standard does not give details about
this criteria and it I left to each discipline to define them. Thus, for the structural
engineering community the specification of Model Views Definitions for structuraldesign, analysis and construction is instrumental for the BIM applications. The
structural engineering community has to be clear in identifying these views so theNBIM standard can incorporate them in the next versions and can be used in theCMM. The authors suggest also in addition to the development of the Model Views
Definitions is to develop a spread sheet to measure the model maturity level in
structural system design and construction to meet the minimum NBIM Standard. This
Structural Model Maturity (SMM) tool should identify the baseline in the structuraldesign, the typical level of BIM in structural engineering and whether the model
meets the minimums requirements.
Figure 7 below show an example of a Model View developed by the ATC(Applied Technology Council, ATC-75) For structural design to detailing. As can be
seen, this MVD is limited and does not represent the general structural systems
aspects.The need for MDV that details the requirements for structural systems design and
construction is not available yet. This study suggests that the MDV for structural
engineering should include specifications about the following:
A- SuperstructureB- Substructure
The superstructure must detail the shell (roof, exterior walls, doors, and windows)
and the system required to support the shell of the structure as well as the interiorsupport system such as floors, walls and partitions ,columns, beams, load bearing
walls, floor and roof structures.The second component of the suggested MDV should specify the substructure
information such as shallow foundations, deep foundations as well as the various
conditions of soil, rock, and water existing in the substrata.
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Figure 7. Model View Definition for Structural Design (ATC-75)
Figure 8 Summarizes the main areas of the suggested MDV for structural analysisand design BIM applications (a detailed MDV will be published in the near future):
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Figure 8. Areas for MDV Structural Design and Analysis
DISCUSSION & CONCLUSIONS
The National Building Information Model Standard (NBIMS) is, by design, a
standard of standards. The NBIMs is based upon other standards, mainly, IAI, IFC,
and Omniclass. From the standpoint of traditional vertical construction, the NBIMSVersion 1 Part 1 defines a minimum standard providing a baseline against which
additional, developing information exchange requirements may be layered. As noted
in the NBIMS version 1, the Standard is not a compendium of other federal standards
rolled into one document. Rather, it is the embodiment of an initiative to improve theperformance of facilities over their full lifecycle by fostering a common, standard,
and integrated lifecycle information model for the AEC & FM industry. The
NBIMS uses the CMM (Capability Maturity Model) to measure BIM projectscompliance with the standard requirements. According to the National BIMStandard Version 1 Part 1, As industry evolves and more rapidly adopts greater
levels of maturity, this model will change to accurately reflect best industry practices.
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For structural systems BIM projects, Structural Model MinimumRequirements need to be specified. Model View Definitions (MVD) is the key for
such successful BIM implementation. Model View Definitions (MVD) is used for
documenting IFC based data exchange capabilities in software. The MVD format wasadopted by the NBIM Standard as the official format for defining views for IFC.
MVDs are structured such, that different audiences can focus on the informationrelevant to them. The main division is between technical and non-technical.Thus, for the structural engineering community the specification of Model
Views Definitions for minimum requirements for structural model for design,
analysis and construction is instrumental for BIM applications. This work suggestedthe general areas of MDVs needed for structural model. Furthermore, the paperproposed the development of a spreadsheet to measure the structural model maturity
(SMM) level in a similar fashion to the CMM. The SMM is suggested to identify the
baseline in the structural design, the typical level of BIM in structural engineeringpractice and whether the model meets the minimums requirements or not.
The paper strived to introduce NBIM standard to the structural engineering
community and bridge NBIMS implementation from theory into practice in a waythat provides goals for the best method to manage building information in an efficient
integrated approach.
REFERENCES
AIA Document E201TM 2007 (2007 ). Digital Data Protocol, American Institute
of Architects, 2007.
American Society of Civil Engineers Structural Engineering Institute/Council ofAmerican Structural Engineers Joint Committee on Building Information
Modeling, http://www.seibim.org
International Alliance for Interoperability (IAI), buildingSMART International,
http://www.iai-international.org.Industry Foundation Classes (IFC), http://www.iai-tech.org (publication of the IFC
specification)
NBIMS (National Building Information Modeling Standard), Version 1,Part 1 (2007). Overview, Principles, and Methodologies, National Institute
of Building Sciences. 12/2007. http://www.nationalcadstandard.org/
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