Getting on Board with Building Information Modeling  

"If you want to survive, you're going to change; if you don't you're going to perish,"
- 2005 Pritzker Prize Laureate, Thom Mayne, FAIA, referring to Building Information Modeling at the 2005 AIA Convention

Architects are increasingly adopting Building Information Modeling (BIM) as standard practice, and rising to the challenge of "change or perish." The sentiment echoing throughout the building design and construction industry is that the days of two-dimensional (2-D) drawing are numbered. BIM allows for more collaborative, integrated design-construction teams that provide value to owners and design professionals.

Like computer-aided design (CAD) in the 1970's, BIM−the process of using three-dimensional (3-D) modeling technology for creating, communicating, and reviewing building information−is the next step in the evolution of the design and construction process. BIM offers a better way of delivering projects in a collaborative and less fragmented fashion that blurs the line between design and construction. With BIM, the project is designed and virtually constructed during the design phase, which allows construction to proceed more quickly in the field, reducing overall project costs, and enabling the building to begin operation sooner. The result is a benefit to owners, and the project team.

The 3-D model of General Motors' new engine plant allowed A/E firm Ghafari Associates and design team members to digitally detect and correct interferences between building components early in design. Photo credit: Ghafari Associates

"BIM is about sharing better information, earlier in the process, and broadly," says Daniel Friedman, FAIA, director of school of architecture, University of Illinois at Chicago. He says BIM holds the potential for immediate quantity surveys, identification of conflicts and omissions, fewer change orders, project delays, and cost overruns, and more clearly defined and shared accountability, risk, and reward.

"BIM will change the distribution of labor in the design phases," says Carl Galioto, FAIA, partner, Skidmore, Owings & Merrill (SOM), New York. "When done correctly, the labor is front-loaded earlier in the design process, during the schematic and design development phases, and less in construction documents."

Steel Industry: A Model for Success

While most architects and other members of the building team are only beginning to apply BIM to projects, the structural steel industry is using 3-D modeling and interoperability−the use of software systems that are able to communicate and exchange data and information through a neutral file format−to integrate the design and construction process and speed the delivery of the structural steel package. Structural engineers are collaborating with steel detailers, fabricators, and erectors to share and exchange 3-D model information to create detailed designs for steel-framed buildings with tight tolerances. On numerous projects, this allowed mill orders to be placed earlier and steel to be delivered and erected on site more quickly, with few, if any field changes required. Fewer field changes enable the steel teams to provide a quality product, with less waste, and greater safety.

T3-D modeling and team integration enabled steel erection of the Denver Art Museum expansion to be completed two months ahead of schedule. Photo credit: Structural Consultants Inc. Design Architect: Studio Daniel Libeskind The 3-D visualization model used on the Denver Art Museum expansion by local architect Davis Partnership, Studio Daniel Libeskind's joint venture design partner, became a BIM model during the project. Photo credit: Miller Hare

Using BIM on General Motors' new $300−million V6 engine plant in Flint, Mich., enabled the steel mill order to be placed eight weeks earlier than typically would be possible and steel erection began eight days early, says Lawrence F. Kruth, P.E., engineering and safety manager for Douglas Steel Fabricating Corp., Lansing, Mich. Construction of the plant was completed five weeks ahead of schedule with no change orders, says Samir Emdanat, manager of advanced technologies for the architectural/engineering firm Ghafari Associates, Dearborn, Mich. BIM enabled the project's integrated building team to shave 24 weeks off what typically would have been an 85-week design and construction schedule. In benchmarking previous projects, GM estimates that three to five percent of total construction costs would have been saved by implementing BIM on those projects, according to Laird Landis, GM's senior technological engineer.

Modeling the steel and mechanical, electrical, and plumbing (MEP) with tight tolerances meant that the steel frame, sheet metal, and piping all fit into place in the field like an erector set, reducing construction waste. Less waste and field work resulted in a safer construction site, with only one injury recorded on the project, which was unrelated to construction activity.

In Denver, the need to understand, document, and coordinate the complex design by Studio Daniel Libeskind for the Denver Art Museum expansion, scheduled to open in Fall 2006, dictated sharing of the 3-D model between Denver architect Davis Partnership and the project's structural engineer, steel connection designer, and steel delivery team. "It's difficult to believe the project could have been done without BIM," says Davis Partnership's Maria Cole, AIA. Working with general contractor M.A. Mortenson, the integrated design-build steel team completed the project's steel erection two months ahead of schedule, after starting the design process two months behind schedule and returning $400,000 to the owner in the process.

Championing a Better Way

The structural steel industry has championed the use of 3-D modeling and the value of a vendor independent suite of interoperable design and fabrication programs since 2001. Those efforts have paid major dividends for steel-framed projects in bringing many of the promised benefits of BIM to the structural framing system segment of projects. The lessons learned by the structural steel industry can be utilized to form a roadmap for design professionals moving toward BIM implementation in their practices.

The structural steel industry recognized that errors made in producing, interpreting and integrating 2-D construction documents were plaguing the construction industry at a time when owners were demanding that projects be completed in less time, while staying on or coming in under budget. Complicating the issue was the continuing pressure being placed on architects and engineers to reduce fees and accelerate schedules. The end result was a decline in the quality of construction documents resulting in an avalanche of requests for information (RFIs) and change orders. This resulted in the stifling of innovative design, increased risk, escalated costs and extended schedules−the exact opposite of the desire of the project owner. The inability of design and construction team members to communicate and exchange data clearly and efficiently through the use of CAD-based technology created an environment that fostered adversarial relationships instead of collaboration and invited litigation. Selected structural steel projects, such as GM's engine plant, the Denver Art Museum expansion, and many others, are overcoming these barriers through the collaborative efforts of structural engineers and steel fabricators using 3-D modeling as a common design and construction vehicle. The transition to this process has not been easy, requiring a redefinition of the design and construction process.

A comparison of a 2-D drawing and a 3-D model of a typical steel connection on the Denver Art Museum expansion illustrates how much easier it is to visualize complex objects using 3-D modeling. Image credits: Structural Consultants Inc.

Architects Making the Transition

Architects and architectural firms are beginning the process of transitioning from existing CAD environments to BIM, utilizing 3-D computer-aided design and construction, training staff, and applying BIM successfully on projects, as part of integrated design and construction teams. For that transition to be effective, BIM must be clearly understood in terms of its benefits, technology, and implementation.

Just as the success of CAD in transitioning building design from the drafting table to the computer required a cultural shift for the entire building design and construction industry, the transition from CAD to BIM tools and processes will require a similar shift as well. Internally, firms need to evaluate how this transition will affect their in-house technology, staff, and their ability to fund and support the transition. Externally, the firm must seek out appropriate projects and partners that they believe lend themselves to the BIM process and move forward.

SOM and Detroit's SmithGroup are two large, multi-office A/E firms making the transition to BIM. SOM's New York office is using 3-D modeling on a number of projects, including New York's Freedom Tower. "We're looking at BIM as being a complete database, as opposed to just 3-D information," says SOM's Galioto. The firm is using the model to arrive at and optimize intelligent solutions, test applications and simulations, such as thermal, daylight, glare, and computational fluid dynamics−the use of technology to study things that flow−for heating, ventilating, and air-conditioning. The firm also is using BIM for collision detection, points in the 3-D model that illustrate where the building's structure and MEP ducts, piping, and equipment improperly intersect with one another.

The next step for SOM is interoperability, the exportation of data and information via the 3-D model, as opposed to producing traditional 2-D drawings. The firm is working with curtain wall manufacturers on this process. "Interoperability is the challenge," Galioto says. "We are spending a lot of time finding ways to get the software to work together. It all comes down to the integration of multiple models. The structural steel industry is ahead of the curve on this."

The goal of SmithGroup, a firm with 800 architects, is to be modeling all of its projects in 3-D in 2006. The firm has implemented BIM on a number of key pilot projects throughout the United States, including a corporate pharmaceutical lab facility in the Detroit area, the new headquarters of general contractor Sundt Construction in Tempe, Ariz., and an expansion of Comer Children's Hospital in Chicago. The Comer project, due to be completed in Spring 2006, is the Chicago office's ninth BIM project, the first to integrate the architecture with the structural steel frame and the mechanical and electrical systems. "BIM is so important for where we're going," says principal Jens Mammen, leader of the Chicago office's BIM transition. "Strategically, BIM is on the verge of revolutionizing how we deliver our projects. We don't draw buildings any more, we build buildings."

In the design of Chicago's Comer Children's Hospital expansion, A/E firm SmithGroup integrated the architectural design with the structural steel frame and mechanical and electrical systems. Rendering credit: SmithGroup

The true value of an integrated BIM project is realized downstream, during the design and construction process. Collision detection and coordination of the project with design and construction team members is where BIM benefits the SmithGroup financially and saves costs on the project, says Mammen. "Fifty percent of coordination is about the 2-D drawing itself," he says. "With the 3-D model, the project is so well coordinated and built so quickly that we're receiving very few questions from the field, especially during the bidding process."

On the Comer project, the firm received only six RFIs in the bidding process, an astoundingly low number compared to the hundreds that would typically be received. For Mammen, the benefits attainable through BIM are too great to ignore: "I can't foresee ever going back to the 2-D world."

Transitioning the Practice

The success of CAD over the last 30 years has resulted in most design firms being so firmly entrenched in the technology that it can create a barrier to the transition to BIM, says SmithGroup principal Rick Thoman, AIA, IT manager in the firm's San Francisco office. But SOM's Galioto says architects will welcome the transition: "By switching to the model, our people say that they feel more like architects because they are working in three dimensions."

Transition to BIM will require research, information gathering, and financial backing of the firm's leadership. Unlike the early days of CAD, when a junior staff member or draftsperson could be placed in front of an early generation PC, given an early version of a CAD package and be told to figure out a "better, faster way to draw," the transition to BIM will require commitment from senior staff members intimately involved with design decisions and processes.

The transition to BIM will require an investment of capital and resources from firms, demanding strong commitment from the firm's management over an extended period of time. In 2006, the typical cost of a BIM application can range between $5,000 and $6,000 or more, but this is only a small portion of the cost. Annual maintenance subscriptions fees, consulting fees, training, current generation hardware, and climbing the learning curve will cost much more than the cost of the software. To ease the transition while holding down costs, firms such as SmithGroup are selecting a software purchasing option called a "crossgrade," which allows a firm to migrate a software license from one software vendor's product to another of its products. This also allows a firm to continue to receive upgrades for both products, says Thoman.

Transitioning a firm can be a complex and challenging process, especially for large, multi-office firms with multiple disciplines. Some suggestions include:

• Consider forming a team comprised of individuals from the different offices and disciplines within the firm, and possibly an outside non-vendor consultant to evaluate the firm's needs, and to develop a perspective on BIM in the industry.
• Appoint one individual at the firm to champion the transition and coordinate the overall process.
• Consider conducting tours of the firm's offices with upper management to explore how to accelerate implementation of BIM. SmithGroup is implementing this practice.
• Conduct just-in-time training of staff on BIM tools in conjunction with actual building projects. SmithGroup, SOM, Ghafari Associates, and others agree that this is the most effective training method. Abstract training won't do, says SOM's Galioto.
• Be proactive about implementing the BIM tools that will prepare the firm to move forward on a project. Care must be taken not to overcommit to a solution until there is a clear understanding of the desired workflow for the trial project. Ideally, the project should be one for a repeat client with whom the firm has a positive, open relationship. The client should be part of the transition process, recognizing the benefits that can accrue, while being aware of the challenges that can often occur on pilot projects.

Enter the transition with a proactive mindset:

• Perform due diligence by conducting research, reading industry reports, white papers, and publications.
• Attend meetings and conferences where BIM is on the agenda.
• Communicate with peer firms to learn about their approach to the transition.
• Seek information and advice from industry professionals who have had success with 3-D modeling and integration to lower costs and shorten project schedules for owners, such as steel industry detailers, fabricators, and structural engineers.
• Use software vendors as information resources and providers of training.
• When using out-of-the-box BIM software, consider developing and writing guidelines for project teams, which will be using the technology, so elements such as title boxes and pull downs will automatically be there for them, as is the case with technology that meets the present CAD standard.

With the steel team utilizing a design-build framework and 3-D modeling, delivery of the structural steel for Mt. Tahoma High School, Tacoma, Wash., designed by BLRB Architects, Tacoma, cut the construction schedule by three months. Rendering credit: Putnam, Collins, Scott Associates

Applying BIM to Projects

Once a firm has conducted its research and is comfortable with the tools it has in place, the best way to get started is to just do it. Experts recommend that architectural firms carefully select projects for BIM and apply them. One litmus test in determining if a project is right for BIM is whether a firm can deliver a completed project to the owner that is cheaper, faster, better, and safer by utilizing the BIM process.

Lanny Flynn, P.E., a structural engineer with Magnusson Klemencic, Seattle, uses this method to drive his use of BIM "to deliver a client the tangible benefits of a faster schedule at a lower cost." While with the Tacoma, Wash., structural engineering firm of Putnam, Collins, Scott Associates (PCSA), Flynn helped promulgate the delivery of the steel for construction of Tacoma's Mt. Tahoma High School upstream to the design phase. This shortened the construction schedule of the 279,000−square foot high school by three months.

A firm cannot implement BIM by acting alone. There must be a commitment from at least some other key members of the building team to make integration of at least part of the project possible. In the case of Mt. Tahoma High School, PCSA, which detailed the project in-house, exported the model to steel fabricator Allied Steel, Lewistown, Mont.

Alliances should be formed with design consultants and contractors who have some experience working with BIM or who are eager and committed to beginning the process. A complex project such as GM's engine plant required a total commitment on the part of the entire building team to make the project a reality in BIM and bring about the productivity gains sought by the owner. Ghafari Associates, the project's A/E firm, teamed with firms it had worked with previously on another GM BIM project, including fabricator Douglas Steel, which has been modeling in 3-D since 1995, and mechanical contractor John E. Green Co., Highland Park, Mich. The design and construction team not only collaborated via the exchange of the 3-D model, the team co-located together in one office, facilitating communication to an even greater extent.

As the GM project demonstrates, the focus of BIM is to increase project productivity in design and construction by designing and virtually constructing a project before the project is built in the field. The transition to BIM is a cultural change that requires a rethinking of the building design and construction industry process. There are hurdles to bringing about such significant changes with BIM, which may generate initial resistance, and must be overcome through clear and open communication with the owner and other members of the building team.

BIM requires some reallocation of:

• Effort
• Cost
• Risk

By shifting a significant portion of the effort, cost, and risk forward during the design phase, the savings to the project and the client is realized on the back end of the project, during construction, through significant increases in productivity, resulting in lower costs and early project completion. This must be communicated to the owner, who must accept the idea of increasing design fees and modifying risk structures, in exchange for lower construction costs through fewer change orders, and an earlier completion of the project.

The need for this reallocation also must be effectively communicated to the building team members, who must commit to the give and take integral to the BIM process. Decisions must be based on what is best for the team and the project. Throughout the course of an integrated BIM project, situations will arise that may require extra effort from team members. An appropriate level of trust and commitment must be built among the team members so that they are comfortable and supportive of the effort and can reasonably expect that somewhere in the course of the project they too will benefit from the process.

It is not necessary that a project utilize design-build project delivery to take advantage of the benefits of the BIM process. However, the greatest value will be achieved utilizing BIM on a design-build project. It is recommended that a firm's initial foray into BIM be on a project characterized by a collaborative design-build culture, and a design-build project. The vertical integration of the structural engineer and steel detailer, fabricator, erectors on projects, such as the GM plant, Denver Art Museum, and Mt. Tahoma High School all utilized a design-build framework to increase productivity. In the steel industry, the formation of design-build alliances is flourishing, with more than 20 such partnerships having been formed throughout the United States in recent years. Such arrangements enable team members to share risk and maximize their effectiveness, resulting in even greater productivity gains to projects.

An expanded scope of project management is a significant issue for architects when implementing BIM. In defining a project earlier with the creation of a 3-D model, there is a need to front-load fees to account for the redistribution of the project management tasks. In this area, the architect must control the client's expectations and the process early on, says SmithGroup's Thoman.

Early integration of the design team, involving the architect, structural engineer, and specialty contractor is essential to BIM.

• The architect should work to bring the design team together, including members such as the steel fabricator, detailer, even the erector, who can add value to the design process, but who typically haven't become involved in the project until the latter stages of design.
• Meetings should be arranged with the design team to layout the ground rules and decide on the process and workflow of the project.
• The purpose of the model and what level of modeling is required for the project should be established. If the team is overly ambitious and attempts to model every minute detail, the model may be at risk of becoming so large and cumbersome that its usefulness is diminished. "The thought used to be to do everything in the model," says SmithGroup's Mammen. "Now we say use the model to the best value." Whatever level of modeling is decided upon, it is critical for the team to always maintain and update the model, says Douglas Steel's Kruth.
• To reduce risk, contract language should designate ownership of the model, how the model will be shared, and who will manage the model at what stages of design. In some cases, there will be one model manager and in others there may be a transitioning of responsibility for the model from one team member to another as design progresses. This varies, depending on the project. On the Denver Art Museum expansion project, general contractor M.A. Mortenson was the designated "model manager." SmithGroup's Chicago office has hired a veteran architect as its dedicated "data manager," responsible for coordinating the various computer files and models that are integrated into a BIM.
• Contract language should also address the issue of review and approval of 3-D shop drawings versus 2-D drawings. AIA is anticipating the release of exhibit documents to supplement its model contracts in late 2006. And other industry groups such as the Construction Users Roundtable (CURT) are at work on contractual issues affecting the sharing of digital information. Another resource is AISC's Appendix A: Digital Building Product Models of the Code of Standard Practice for Steel Buildings and Bridges.
• Collaboration, team integration, and communication are the key to any BIM project. Architects experienced with BIM in an integrated design team approach would argue that the risk involved to the team members is actually less than with a conventional delivery method, because of the collaborative environment and trust that is built into the process. "The risk actually goes down with integrated design because everyone has a stake in the process," says J.R. Barker, P.E., S.E., of Structural Consultants Inc., Denver, the connection design firm for the Denver Art Museum expansion. Through integration and collaboration, issues are raised and resolved digitally, before they become larger problems later in the project, causing delays, increasing costs, and raising tensions.

The Time is Now for BIM

There are still those who insist that new technologies and processes will not gain traction in design and construction. Their arguments are that the old ways are too entrenched, the new technologies too expensive, the project delivery processes too complex, software not yet up to the task, and the desire for change too nebulous for meaningful change to occur. Yet the litany of complaints about design and construction continue: failure to improve productivity, decreasing quality of construction documents, poor communication and coordination, cost overruns, change orders, extras, project delays, and lack of adequate labor resources.

Building Information Modeling provides a process and vehicle to positively impact the design and construction process and enhance project productivity. BIM is increasingly being used in the design and fabrication of projects. Architects, structural engineers, general contractors, and steel fabricators using BIM are delivering projects that are completed faster, are less expensive, of higher quality, and safer than those of the competition.

AISC Trade Association

The American Institute of Steel Construction, Inc. is a not-for-profit technical institute and trade association established in 1921 to serve designers, contractors, and owners. AISC's activities include specification and code development, research, education, technical assistance, quality certification, standardization, and market development. AISC works with architects, contractors, engineers, and owners to develop steel framing solutions tailored to schedule-driven and design-build projects. For assistance with a project, contact the AISC Steel Solutions Center at 866.ask.aisc or emailsolutions@aisc.org.

Guidance for Use of Digital Building Product Models

Gaining the full advantage of Building Information Modeling necessitates that a digital 3-D building model replaces the traditional 2-D paper contract drawings. In order to address this major shift in practice, the American Institute of Steel Construction has taken the lead by adding Appendix A: Digital Building Product Models to the Code of Standard Practice for Steel Buildings and Bridges, March 18, 2005. Appendix A, available along with the entire Code of Standard Practice for free download atwww.aisc.org/code, provides guidance for the use of digital building product models.

APPENDIX A.
DIGITAL BUILDING PRODUCT MODELS

The provisions in this Appendix shall apply when the contract documents indicate that a three-dimensional digital building product model replaces contract drawings and is to be used as the primary means of designing, representing, and exchanging structural steel data for the project. When this is the case, all references to the Design Drawings in this Code shall instead apply to the Design Model, and all references to the Shop and Erection Drawings in the Code shall instead apply to the Manufacturing Model. The CIS/2 Logical Product Model shall be used as the building product model for structural steel.

If the primary means of project communication reverts from a model-based system to a paper-based system, the requirements in this Code other than in this Appendix shall apply.

Commentary:

Current technology permits the transfer of three-dimensional digital building product model data among the design and construction teams for a project. Over the last several years, designers and fabricators have used CIS/2 as a standard format in the exchange of building product models representing the steel structure. This Appendix facilitates the use of this technology in the design and construction of steel structures, and eliminates any interpretation of this Code that might be construed to prohibit or inhibit the use of this technology. While the technology is new and there is no long-established standard of practice, it is the intent in this Appendix to provide guidance for its use.

Glossary

Building Product Model. A digital information structure of the objects making up a building, capturing the form, function, behavior and relations of the parts and assemblies within one or more building systems. A building product model can be implemented in multiple ways, including as an ASCII file or as a database. The data in the model is created, manipulated, evaluated, reviewed and presented using computer-based design, engineering, and manufacturing applications. Traditional two-dimensional drawings may be one of many reports generated by the building product model (see Eastman, Charles M.: Building Product Models: Computer Environments Supporting Design and Construction; 1999 by CRC Press).

CIS/2 (CIMSteel Integration Standards/Version 2). The specification providing the building product model for structural steel and format for electronic data interchange (EDI) among software applications dealing with steel design, analysis, and manufacturing.

Logical Product Model (LPM). The CIS/2 building product model, which supports the engineering of low-, medium- and high-rise construction, in domestic, commercial and industrial contexts. All elements of the structure are covered, including main and secondary framing and connections. The components used can be of any variety of structural shape or element.

The LPM addresses the exchange of data between structural steel applications. It is meant to support a heterogeneous set of applications over a fairly broad portion of the steel lifecycle. It is organized around three different sub-models: the Analysis Model (data represented in structural analysis), the Design Model (data represented in frame design layout) and the Manufacturing Model (data represented in detailing for fabrication).

Data Management Conformance (DMC). The capability of the CIMSteel model to include optional data entities for managing and tracking additions, deletions and modifications to a model, including who made the change and when the change was
made for all data changes.

A1.2. Referenced Specifications, Codes and Standards

Add the following reference to Section 1.2:
CIMSteel Integration Standards Release 2: Second Edition P265: CIS/2.1: Volumes 1 through 4.

A3. Design Drawings and Specifications

In addition to the requirements in Section 3, the following requirements shall apply to the Design Model:

A3.1. Design Model

The Design Model shall:

(a) Consist of Data Management Conformance Classes.
(b) Contain Analysis Model data so as to include load calculations as specified in the Contract Documents.
(c) Include entities that fully define each steel element and the extent of detailing of each element, as would be recorded on equivalent set of structural steel design drawings.
(d) Include all steel elements identified in the Contract Documents as well as any other entities required for strength and stability of the completely erected structure.
(e) Govern over all other forms of information, including drawings, sketches, etc.

A3.2. LPM Administration

The Owner shall designate an Administrator for the LPM, who shall:

(a) Control the LPM by providing appropriate access privileges (read, write,etc) to all relevant parties.
(b) Maintain the security of the LPM.
(c) Guard against data loss of the LPM.
(d) Be responsible for updates and revisions to the LPM as they occur.
(e) Inform all appropriate parties as to changes to the LPM.

Commentary:

When a project is designed and constructed using EDI, it is imperative that an individual entity on the team be responsible for maintaining the LPM. This is to assure protection of data through proper backup, storage and security and to provide coordination of the flow of information to all team members when information is added to the model. Team members exchange information to revise the model with this Administrator. The Administrator will validate all changes to the LPM. This is to assure proper tracking and control of revisions.

This Administrator can be one of the design team members such as an Architect, Structural Engineer or a separate entity on the design team serving this purpose. The Administrator can also be the Fabricator's detailer or a separate entity on the construction team serving this purpose.

A4.3. Fabricator Responsibility

In addition to the requirements in Section 4.3, the following requirements shall apply:

When the Design Model is used to develop the Manufacturing Model the fabricator shall accept the information under the following conditions:

(a) When the design information is to be conveyed to the Fabricator by way of the Design Model, in the event of a conflict between the model and the Design Drawings, the Design Model will control.
(b) The ownership of the information added to the LPM in the Manufacturing Model should be defined in the Contract Documents. In the absence of terms for ownership regarding the information added by the Fabricator to the LPM in the Contract Documents, the ownership will belong to the Fabricator.
(c) During the development of the Manufacturing Model, as member locations are adjusted to convert the modeled parts from a Design Model, these relocations will only be done with the approval of the Owner's Designated Representative for Design.
(d) The Fabricator and Erector shall accept the use of the LPM and Design Model under the same conditions as set forth in Paragraph 4.3 with regard to CAD files, except as modified in A4.3 above.

A4.4. Approval

In addition to the requirements in Section 4.4, the following requirements shall apply:

When the approval of the detailed material is to be done by the use of Manufacturing Model the version of the submitted model shall be identified. The approver shall annotate the Manufacturing Model with approval comments attached to the individual elements as specified in the CIS/2 standard. As directed by the approval comment the Fabricator will reissue the Manufacturing Model for re-review and the version of the model submitted will be tracked as previously defined.

Commentary:

Approval of the Manufacturing Model by the Owner's Designated Representative for Design can replace the approval of actual shop and erection drawings. For this method to be effective, a system must be in place to record review, approval, correction and final release of the Manufacuring Model for fabrication of structural steel. The versions of the model must be tracked, and review comments and approvals permanently attached to the versions of the model to the same extent as such data is maintained with conventional hard copy approvals. The CIS/2 standard provides this level of tracking.