Structural Steel Shop Drawing Review: The Present — the Future
Structural Steel Shop Drawing Review: The Present — the Future
By Michael Gustafson, P.E.
August 2008
Structural Steel Shop Drawing Review: By Michael Gustafson, P.E. The Present — the Future
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he structural steel detailing industry has continued to expand its use of 3D modeling technology in recent years; currently more than 50 percent of the structural steel detailing market in the United States is using some form of 3D modeling software (American Institute of Steel Construction, 2007). This change has brought great efficiencies to the steel detailer’s own productivity, in addition to improving upstream and downstream processes. Structural engineers, on the other hand, have not seen the same improvements in their own productivity in reviewing and approving structural steel shop drawings. In fact, some engineering firms may argue that the average number of shop drawings to review per project has increased over the years. More recently, however, engineering firms are finding new ways to increase their productivity in reviewing and approving shop drawings using a range of emerging technologies. The transfer of shop drawing submittals electronically was the first step in using digital technology, but now enhanced visualization methods of reviewing and approving shop drawings are now being implemented.
Project requirements of the EOR in shop drawing review The American Institute of Steel Construction (AISC) Code of Standard Practice (COSP) outlines what is required of the steel fabricator and of the engineer-of-record (EOR) in submission and approval of shop drawings. Minimal information is provided regarding the content to be reviewed by the EOR since this is typically outlined at the project level by the EOR and defined in the project specifications. The COSP states that the steel fabricator expects a 14-calendar-day turn around from the day it releases drawings to the day the fabricator receives the approved shop drawings back from the EOR. If modified in the contract documents, the actual turn around time is governed by the EOR’s project specifications. With the nature of today’s accelerated project delivery schedules, a two-week turn around time of shop drawings is not the norm, thereby putting more stress on the review team to be more productive and turn around approved submittals in less time. A signed set of calculation sheets from a professional engineer for all connection designs not covered by the design drawing contract documents is often stated in the project specifications when the work of connection design is delegated. Engineering firms require this because the COSP states that the EOR shall review and approve structural connections and details designed by others (see COSP – Section 4.4.1). The submittal of connection calculations and verification of the calculations does impact the efficiency of the shop drawing review process.
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Standards for shop drawing review The EOR has an obligation to verify that the structural design intent is being properly communicated by the steel fabricator on its shop and field drawings. The steps and
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The learning objectives of this paper are the following: Understand current contractual and industryexpected responsibilities of the engineer-of-record in the shop drawing review process. Identify inefficiencies or redundancies in the current review processes. Learn how 3D visualization tools can be used to coordinate, review, and approve shop drawing submittals while still delivering a 2D submittal of shop drawings. Comprehend industry trends moving toward a 3D model-based shop drawing review process.
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Structural Steel Shop Drawing Review: The Present — the Future procedures of how this is conducted are determined by the EOR or, more commonly, by a company standard. Typically, structural engineers follow a checklist for reviewing and approving the erection and assembly shop drawings. Each engineering firm has its own standard for how much detail needs to go into checking shop drawings. Typically, the structural assemblies — comprised of primary framing and connection parts — are reviewed for compliance at three levels: within the context of other building systems, within the context of other structural assemblies and structural systems; and within their own structural assembly. Furthermore, for each level of investigation, several design parameters are typically reviewed, such as geometry, section properties, and material properties. Checking each of these parameters can be a tedious process. In addition, the task of reviewing each checklist item on the shop drawings and comparing that information with the design drawings accumulates a fair amount of inefficiency. The steel fabricator’s 3D model (also referred to as the construction model) can help the EOR in many ways better visualize and review the shop drawings, as well as speed up the EOR’s time reviewing the shop drawings.
Workflows using the 3D construction model For more than 55 percent of the projects built in the United States that detail structural steel (AISC, 2007), the EOR may obtain access to the 3D construction model for review of shop drawing submittals. Such a tool can be help ful in improving the EOR’s understanding of the proposed fabricated product by the steel fabricator. Several work flows can be utilized to leverage different levels of the 3D construction model in the review process. These workflows range from using the 3D model as an enhanced visualization tool — which still requires 2D shop drawings as the final, commented, and approved submittal to the fabricator — to the approval of the 3D construction model in lieu of 2D drawings. In this paper, we refer to three workflows that use different tools to review and approve the shop drawings: 2D Review, 2D-3D Review, and 3D Review. Note that the first workflow, 2D Review, basically represents the traditional shop drawing approval process in which the structural engineer’s paper design drawings are used along with the fabricator’s submitted paper shop drawing set. This workflow’s use of the 3D model is limited to including colored markers to make comments. The inefficiencies that exist in this typical workflow can be improved upon using either the 2D-3D Review or the 3D Review approach, which are discussed next.
workflow assumes that the 2D shop drawings are still the final document containing the approval comments by the EOR. In other words, use of the 3D model makes the review process more efficient and visual but does not replace the deliverable of 2D paper approval drawings. Key steps in the 2D-3D Review workflow are discussed below. Step 1. Coordination of building systems — As a first step, the EOR may wish to check for constructability issues between the structural systems (such as structural steel, cast-in-place concrete, precast, etc.) that have surfaced during the shop drawing stage that ultimately could affect the final design. In this context, constructability is not being defined by means and methods (which is typically not part of the EOR’s scope of work), but rather referring to the quality of the final, in-place structure. Therefore, using the 3D construction model to aid in the review process can be appropriate. To coordinate interfaces of the structural steel frame with other structural elements such as concrete foundations and walls or roof joists, structural engineers can import their 2D design drawings or 3D structural models, including building information models (BIMs), into the construction model. The overlaying reference can be used to verify the steel structure geometry as well as clearances and tolerances (see Figure 1). The geometry of the model elements can be reviewed in reports that can be created within the construction model, or from the model elements themselves. An obvious benefit of referencing the 2D design drawings within the context of the construction model is that the contents of both are superimposed together in one spot. This eliminates the EOR’s need to go back and forth between design plans and the fabricator’s erection drawings. To coordinate the structural steel frame with non-structural elements such as exterior wall locations, floor open-
Figure 1: An example of 2D-3D Review workflow includes coordination of the 3D structural model, 2D design drawings, and the 3D steel construction model.
2D-3D Review workflow The 2D-3D Review workflow follows the traditional work flow of the EOR approving 2D paper drawings, but the process incorporates the 3D model. To clarify again, this
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Structural Steel Shop Drawing Review: The Present — the Future ings, and grade elevations, the reviewer can overlay other 2D drawings or 3D reference models into the steel construction model. Step 2. Review and approval of assemblies — As described above, enhanced visualization tools exist to help the EOR better understand how their design intent is being interpreted by the builders. With this in mind, there are opportunities to improve the actual approval process itself for the EOR, specifically with finding, commenting on, and approving each assembly. Some structural engineering firms have tried reviewing and approving 2D drawings in electronic form using 2D redlining tools and have found limited benefits. The 2D-3D Review workflow is different because it can reduce inefficiencies of searching and coordinating information between the design and shop drawings. For example, the EOR can spend a fair amount of time sifting through a stack of shop drawings trying to find the assembly sheet that they wish to review. In contrast, the 3D model can be queried for a specific assembly in the model, and then open the corresponding 2D electronic shop drawing to view the assembly as needed. Secondly, review of the standard materials and parts on a project is currently achieved by checking for those standards on each shop drawing, even though they are repeated across similar assemblies. However, a fabricator’s construction model typically allows the user to view lists of such standard information in reports, allowing the EOR to quickly review larger quantities of data and then to compare and contrast that data with other assemblies. For example, a report that lists each part in the model with its corresponding material grade. Therefore, all the material grades of structural framing members can be verified as A992 in the list, while structural plate and miscellaneous steel can be verified as A36 or A572/50 as specified for the project. Step 3. Comment on assembly — The 2D-3D work flow allows the user to review and make comments within the 3D model environment that correspond to the 2D electronic shop drawings (see Figure 2). The approval status of each element or assembly in the model can be shown in different colors and is also reflected on the 2D electronic drawing as a custom stamp. This linking of the 3D model to the 2D shop drawings in PDF format allows the EOR to review the 3D model, the 2D shop drawings, or both; and simultaneously maintains the approval status linked between them. With the final approved 2D shop drawings in PDF format, the documents can be saved with restricted privileges or simply plotted out as a record set and submitted back to the fabricator as required. Step 4. Connection design review — It is recommended that the fabricator and engineer agree on a preapproval process where the EOR pre-approves the design calculations and associated connection parameters prior to reviewing the shop drawings. This is already a common practice with the current 2D Review workflow. Each type
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Figure 2: An example of an approved assembly shown in both the 3D model and on the 2D electronic drawings in PDF format.
of connection can be assigned an agreed upon connection grouping so that the connections can be easily identi fied in the model during the verification process and cross referenced with the design calculations. During connection design approval process, the EOR can also utilize the fabricator’s model to verify the connection design within the context of the primary structure, as well as better visualize the load paths and constructability of the design. During review of the shop drawings or model, the EOR can then verify that the specified design code is valid at each connection location, or even viewed in conjunction with the provided submitted calculation sheets by the connection engineer.
3D model-based shop drawing review The use of integrated project delivery (IPD) methods, in conjunction with the use of BIM, is bringing forth new business models and workflows in reviewing and approving structural steel shop drawings. Today, numerous projects have been built where the review process was compressed due to the use of a digital review of the 3D construction model by the EOR (McGraw-Hill, 2007). These 3D modelbased review processes have been documented and are now migrating into the mainstream work processes for structural engineering firms, especially those leveraging BIM technology. Note that several entities in the building and construction industry have taken note of the benefits of modelbased review workflows used to date and are documenting how the industry could adopt such processes. For example, the owners group, Construction Users Roundtable (CURT), produced a white paper in 2006 that recognized the inef ficiency in current business models that do not compensate design firms for using digital design information exchanges
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Structural Steel Shop Drawing Review: The Present — the Future to expedite the shop drawing and fabrication processes. Also, the American General Contractors Association’s “Guide to BIM” (2006) states, “Shop drawings could be developed simultaneously as the design unfolds…eliminating the need for approvals and submittal turn arounds, as that process will already have been accomplished during the design period.” Such statements imply the use of an IPD process. Furthermore, the structural steel industry’s AISC has modi fied its COSP by adding Appendix A to accommodate the use of digital design and/or fabrication models to be used instead of design and/or shop drawings given the project requirements (see COSP, Appendix A, 16.3-65). Using a 3D Review approach, the EOR coordinates and reviews the model using procedures similar to that of the 2D-3D Review approach; however, how the EOR approves and communicates their approval is different than using 2D drawing submittals. Instead of using paper drawings, the EOR provides the steel fabricator, depending upon the technology being used, the submittal comments and approval status in electronic form as a file exported from the model. This file is then submitted to the steel fabricator’s detailer who imports and views the EOR’s approval status and comments into his or her own construction model. Note that the EOR does not have to submit an actual model, but only submits comments to the fabricator’s detailer. That way there is no concern with the EOR changing the fabricator’s model during the review process. What can be used as a record-set of the approved submittal is the approval file of each assembly reviewed, as well as the construction model archived in a neutral file format (such as CIS2, XML, etc.) that maintains all the construction information per submittal, and which can be retrieved easily and with accuracy at a later date. The benefits of the 3D Review approach are that it does not require 2D shop drawings to be produced. The EOR can still recognize the same benefits outlined in the 2D-3D Review process above, with the exception of needing to stamp 2D electronic drawings as the submitted deliverable, which is eliminated in this process.
A new approach to shop drawing review If you are interested in incorporating either the 2D-3D Review or 3D Review workflows on your next structural steel project, the first step is communicating early in the project with the project team, including the steel specialty contractor. One way of facilitating this dialog is by hosting a pre-coordination meeting held between the owner’s representative, steel contractor (detailer and/or fabricator), structural engineer, and general contractor involved in the shop drawing submittal process to determine what type of model-based review process can be realistically achieved. Depending upon which workflow is utilized, the project team members may have to adjust certain aspects of their workflow to accommodate a different process. Suggested items to discuss include the following:
Deliverable of submittals — The type of documentation required for submittal process — whether paper, 2D electronic, or 3D model-based — must be established first since it can affect other aspects of the review workflow. Defining project roles and responsibilities — The type of information that the EOR wishes to review should be defined up front so that rights and privileges can be set up properly in the technologies being utilized. This may relate to both modeling software as well as PDF redlining software. Pre-work by steel fabricator — Any set up by the steel fabricator’s detailer, such as plotting shop drawings in PDF format, shall be coordinated up front. Also, the scope of content included in the 3D model to be approved shall be agreed upon. Pre-approved connections — Having the EOR preapprove as many connection designs and connection groups as possible will make checking the model much easier. Establishing how the pre-approval process will work and what the EOR’s expectations are for design calculations can be discussed. Stamping and approvals — The fabricator’s detailer can be asked to set up the electronic stamp template for the EOR so that when the shop drawings are sent to the engineer, stamping the drawing does not require the EOR’s stamp and signature. Electronic stamps could also be set up in advance so that during the redlining process, the approval can be performed on the 2D electronic drawings within the file format agreed upon, such as a PDF, and saved. Review of approved shop drawings by the steel fabricator — Depending on the workflow used, the fabricator’s detailer may wish to receive the approval status information in a specific file format, not just in PDF format, to improve his or her management of received submittals. Managing resubmittals — Resubmittals or successive submittals must be clearly marked as to what information is to be reviewed or re-reviewed by the EOR. Traditional methods use clouding of drawings to communicate such changes. However, a 3D model with status information could be used so that the project team can better visualize what his or her responsibility is to review.
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Conclusion Building and construction industry experts anticipate significant changes to their industry because of the convergence of three industry trends: BIM, IPD methods (such as design-build), and sustainability (Cross, 2008). The impact of the convergence could offer big benefits toward project productivity and also for how projects are managed and delivered. The 3D model-based review workflows discussed above find synergies with these three trends. First, BIM can help engineers better visualize not only their
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Structural Steel Shop Drawing Review: The Present — the Future design intent, but the construction team’s interpretation of the design intent during the shop drawing review stage. Secondly, project delivery methods that capitalize
References American Council of Engineering Companies, 2007, Design & Construction Industry Trends Survey American Institute of Steel Construction, Feb. 2007, “2007 Structural Steel Detailer Listing,” Modern Steel Construction Construction Users Roundtable, 2006, White Paper 1202, p.7 Cross, John, April 2008, “Hat Trick,” Design-Build Dateline , Vol. 15/No. 4 Ghafari & Associates, 2007, Breakthrough Results on General Motors Project Series McGraw-Hill, 2007, Interoperability in the Construction Industry, Smart Market Report, p. 24-25
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on the expertise of structural steel specialty contractors, as well as that of the structural engineer, will further enable the use of 3D model-based review workflows during the shop drawing review stage. For example, a recent domestic project demonstrated a reduction of 25 percent in the overall project schedule when implementing a 3D modelbased review of the structural steel shop drawing submittals using an integrated project delivery process (Ghafari & Associates 2007). Third, the growing trend of sustainable design is giving structural engineers an opportunity to better promote their capabilities in producing sustainable designs for clients. Using less paper during the structural steel shop drawing review process could in effect help create a more sustainable project delivery method. Rough estimates show that more than 65 million sheets of paper shop drawings were used to procure the structural steel shop drawing review process for projects in the United States in 2007 (Survey of 100,000 tons of projects delivered in the United States in 2007). With such benefits being recognized, the structural engineering industry will move ahead with more effective
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collaboration methods with the construction team, while the structural engineer can use a more productive, accurate, and even more enjoyable process in approving structural steel shop drawings.
Michael Gustafson, P.E., is the engineering product manager for North America at Tekla Inc. He can be reached at
[email protected].
Professional Development Series Quiz 1. Per AISC COSP Section 4.4.1, a signed set of calculation sheets from a Professional Engineer is required by the project specifications when what scope of the structural steel design is delegated: a) Foundation elements
6. When using the 2D-3D Review workflow, how can the EOR utilize a 3D construction model during the review and approval of assemblies? a) Search for assemblies in the model b) View reports of standard material lists of the assemblies
b) Mechanical ductwork c) All connection designs not covered by the Design Drawing contract documents d) Architectural concrete-masonry 2. The COSP states a turn-around time the steel fabricator expects from when it releases to when the fabricator receives the approved shop drawings from the EOR. What is that time frame? a) 7 calendar days
c) Comment and stamp 2D PDF shop drawings through the 3D model d) All of the above 7. Which topics are suggested to be discussed during a shop drawing review pre-coordination meeting with the project team? a) Deliverable type of submittals b) Pre-approved connections
b) 14 calendar days
c) Managing resubmittals
c) 21 calendar days
d) All of the above
d) none of the above 3. The EOR will typically check the following design parameters on a shop drawing EXCEPT: a) Temporary shoring requirements of the steel erector b) Geometry of assembly c) Section properties of assembly d) Material properties of assembly
8. Which structural steel industry document states that the use of digital design and/or fabrication models can be used instead of design and/or structural steel shop drawings? a) AISC Code of Standard Practice – Appendix A b) CURT – AGC – AIA 3XPT document c) BIM Addendum to the Consensus Docs
4. The estimated percentage of structural steel projects in the United States that use 3D modeling for structural steel detailing is: a) More than 90 percent b) More than 50 percent
9. A 3D Review method differs from a 2D-3D Review process in what following way(s)? a) It uses paper drawings as the deliverable of submittals
c) Less than 40 percent
b) It uses electronic 2D drawings as the deliverable of submittals
d) Less than 30 percent 5. When using the 2D-3D Review workflow, what are the benefits of referencing structural design drawings and other 3D design models into the structural steel construction model? a) To coordinate the structural steel frame with other structural elements b) By reviewing the architectural model, the EOR relieves the architect of all responsibility in coordinating the accuracy of their design c) To view assembly information and design drawing information at the same time during the approval process d) a and c
d) PCI Handbook
c) It uses a digital 3D construction model, in conjunction with EOR approval comments to the model, as a deliverable of submittals d) Both a and b 10.
What is the estimated number of drawing sheets used to create structural steel shop drawings for all U.S. projects in 2007?
a) 2.5 million b) 10 million c) 65 million d) 500 million
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Tekla Welcomes you to
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Proud Sponsor of the 2008 Structural Engineers’ Building Conference and Expo, October 2-3, Hyatt Regency Atlanta, GA
Gwinnett Arena Georgia Aquarium Cobb Energy Centre The above structures fabricated by SteelFab, Inc. and detailed by Hutchins & Associates, Inc.
Gwinnett picture courtesy of Rosser International, Inc.
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