the role of national bim standard in structural design

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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.

16602010 Structures Congress 2010 ASCE

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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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