AECbytes "Building the Future"
Article (February 17, 2011)
AGC’s Winter 2011 BIMForum, Part 1
Last week, I attended the Winter 2011 BIMForum event that was held in San Diego. The BIMForum is an organization established under the aegis of the AGC (Associated General Contractors of America) to facilitate and accelerate the adoption of BIM in building design and construction. I first wrote about the AGC’s BIM initiatives in Oct 2006 when I attended the annual midyear meeting of the AGC held in San Francisco. This event marked the early efforts of the AGC to promote the use of BIM among contractors with some BIM-focused sessions as well as the first release of its publication, Contractors' Guide to BIM. Since then, the AGC’s BIM efforts have accelerated with the growing adoption of BIM by construction companies and the establishment of a formal organization, the BIMForum, to push this adoption even further. The AGC has also recently released the 2nd Edition of its Contractors' Guide to BIM. This article is the first of a two-part series that provides an overview of the BIMForum organization and captures the highlights of its recent event in San Diego.
Overview of BIMForum
While the BIMForum was initially established to accelerate BIM adoption among contractors, the increasing move towards IPD (integrated project delivery) has broadened its scope to include the entire AEC industry rather than just the construction sector. In fact, its mission now goes even beyond just the adoption of BIM technology; instead, it seeks to encourage greater collaboration in the project delivery process in the AEC industry by facilitating the adoption and use of BIM technology and processes. It is working with other industry organizations such as AIA, NIBS, NIST, buildingSMART, C3T, 3xPT, and CURT to jointly develop best practices for virtual design and construction (VDC). The BIMForum is chaired by John Tocci of Tocci Building Corporation, which is well known for its use of BIM and other advanced technologies.
One of the means by which the organization shares its experiences and executes its goals is by putting together industry conferences on various themes related to BIM and IPD. These are currently held thrice a year. The Winter 2011 event that was held last week was focused on the theme, “BIM and Building Enclosures.” It stemmed from the recognition that the building envelope is one of the most litigious and expensive aspects of building construction and sought to highlight real-world examples of projects where teams have used BIM to address the challenges of designing, fabricating, constructing, and managing the building envelope. The event drew well over 300 people from all the building-related disciplines—the majority were contractors, of course, but there were also many architects and engineers and several owner representatives as well. I was attending this event for the first time and found the diversity of content and audience very informative and intellectually stimulating. In addition to the presentations from AEC project teams, there were also some “rapid-fire” presentations from technology vendors highlighting key updates and new product releases.
The BIMForum concluded with the presentations of the five finalists from the “Delivery Process Innovation” category of the 2011 AIA TAP BIM Awards, providing the audience as well as online viewers the opportunity to vote for the project/team that they thought should win the award. The TAP Committee will take these votes into account in addition to the assessment by the jurors when deciding on the winning entry. The winners in all the categories will be announced on May 11, just prior to the AIA 2011 National Convention in New Orleans. AECbytes provided detailed overviews of the winning projects for the 2006 as well as 2007 TAP BIM Awards, and hopes to do the same once the 2011 winners are announced.
Using BIM for Risk Management
The BIMForum started with a look at the risk management challenges of building enclosures presented by Pat O’Connor of Faegre & Benson, a law firm, and Brian Kramer of Quality Built, a construction quality assurance and inspection management firm, and Twining Inc., which provides geotechnical engineering, construction materials testing, construction testing, and other related services. Given their areas of expertise, both presenters were well qualified to discuss professional insurance for AEC firms and claim statistics. Based on their experience, most of the claims in buildings are related to its HVAC systems, plumbing, and the building enclosure. The common defects are water infiltration, mold, glass breakage, unexpected settlement, and loss of attachment. Defects often occur because the building does not adequately meet seismic conditions or fails to withstand unexpected snow and wind loads, such as those accompanying a powerful hurricane.
While architecture and engineering firms are already using BIM very effectively for building design and engineering, the use of BIM for construction inspection can greatly help to improve the building quality and detect and fix possible defects, thereby reducing the risk of litigation. For example, the use of 3D details from the BIM model to supplement the traditional 2D images can help to make the construction clearer to inspectors. Another example is sending the BIM model to a handheld device in a way that allows the modeling data to be viewed for a specific part of the building that is being inspected on site, enabling the inspector to verify what is actually built with what it is supposed to be built. In short, BIM can enable a clearer explanation of the design and construction of a building, reducing the dependence of AEC firms upon liability insurance—which is typically very expensive—as well as the time AEC firms spent with lawyers—which can be better spent on their core competencies.
Continuing with the theme of risk management, Nathan Wood of DPR Construction showed how BIM was used to identify issues between the vendor shop drawings and the architect’s design model for its Sutter Medical Center Castro Valley (SMCCV) project in California (see Figure 1). Recall from the detailed case study of this project published in AECbytes in March 2009 that the SMCCV was one of the early ground-breaking IPD projects in the US, showing how this new design and delivery method could successfully be applied to large, complex projects. DPR Construction was the General Contractor for this project, which also included GHAFARI Associates as part of the IPD team for project integration and BIM management. While the BIMForum presentation of this project described many of the collaboration and coordination strategies already discussed in my case study, such as the biweekly “big room” on-site, face-to-face meetings for the entire project team from all the different firms involved, it also focused on the specific challenges of the building envelope for this project. These included seismic conditions, challenging building geometry, and four different skin systems installed by three different subcontractors, with many interfaces occurring at odd angles and differing elevations.
Figure 1. A bird’s eye view of the complete model for the SMCCV project. (Courtesy: DPR Construction).
The process for coordinating the fabrication model with the design model was somewhat roundabout and long-winded. It involved matching 2D drawings generated from the architect’s Revit model with the 2D shop drawings created by the fabricators in AutoCAD. Also, the 2D shop drawings were used to create a detailed fabrication model in Tekla Structures, which was then compared with the Revit design model to visually inspect the differences. Through this process, several errors were detected including clashes and gaps between elements and incorrect window locations, which were then fixed prior to construction (see Figure 2). The model was also used to explore many additional constructability issues related to walls, doors, roofs, flashing, and so on. Once the construction was underway, DPR also used laser scanning to determine the exact as-built conditions of specific elements and compare those with the fabrication model. Slight differences were found, which were then used to adjust the fabrication model so that the elements still to be constructed would properly fit into what was already constructed.
Figure 2. Errors detected while checking the fabrication model against the design model. (Courtesy: DPR Construction).
According to DPR, growing architectural complexity increases the need for a fabrication level exterior model which can serve the fabricator’s needs as well as be used for multi-disciplinary coordination, reducing the possibility of errors and overall risk for the building envelope. At the same time, DPR does acknowledge that the fabrication model should ideally be derived directly from the design intent model rather than following the roundabout process it now follows—the description of which was quite unsettling to many of the architects in the audience!
Using BIM to Integrate Design and Construction
Next, there was a joint presentation by Rebecca McWilliams of Symmes Maini & McKee Associates, (SMMA) and Mark Imse of Dimeo Construction on the new corporate office facility for Blue Cross Blue Shield of Rhode Island, which both their firms have worked on. SMMA did the architecture and engineering while Dimeo was the construction manager for the project. It is a 325,000 sq.ft.13-story office tower built on top of an underground parking garage at Waterplace Park in downtown Providence. The presentation was focused on the BIM process used in designing and building the exterior curtain wall for the project. The key challenges were an urban congested site, the waterfront that was an important aspect of the design, and the signature nature of the project, making the exterior design especially important.
SMMA built a detailed architectural BIM model of the building’s exterior, which was used by the fabricators to create 2D shop drawings (see Figure 3). While a full structural BIM model was not built due to the lack of expertise of SMMA in Revit Structure at that time, the architectural model provided the building geometry for structural analysis when required, such as the curved curtain wall sails that rise more than two stories above the building. Similarly, an MEP model was not created because Revit MEP had not yet been launched, but the architectural model again provided the input needed by applications such as eQuest for HVAC analysis. The model was also used for construction coordination in Navisworks, allowing the construction team to detect many complex conditions in the envelope and enabling faster installation of the curtain wall with fewer issues. For example, the model helped in triple-checking each of the 25,000+ clips needed for the curtain wall and coordinating their installation. The project is LEED Silver certified, which is remarkable considering that only in-house tools were used for thermal and daylighting analysis. SMMA has since started using IES but acknowledges that the process is far from smooth, as a lot of “dumbing down” of Revit data is needed to get it into IES.
Figure 3. The detailed architectural model of the Blue Cross Blue Shield project. A close-up view of the entry is also shown on the right. (Courtesy: SMMA).
Use of BIM and Virtual Mockups by Construction Firms
We then had a presentation by Dace Campbell of BNBuilders who shared how this mid-size construction firm was using BIM for the constructability review of building enclosures. It has been using BIM since 2006 but does not have any BIM specialists as such, preferring to push BIM out to all its engineers. Its guiding mantra for BIM is: “Don’t do rework; do prework.” It has used BIM as a virtual mockup to study constructability of enclosure details across a variety of project types, sizes, and delivery methods, enabling it to discover and resolve discrepancies between design intent and means/methods prior to actual construction.
Based on its experiences with BIM, BNBuilders has put together a set of recommended best practices which are: build the model first, then add 2D detail; share the model whenever possible; assign responsibility for each part of the model; make sure that there is only one copy of each element, and don’t duplicate elements between disciplines; model accuracy is more important than level of detail; some details can also be shown in 2D or in cross-sections, so don’t weigh the model down with too much detail; absolutely do not use dimension over-rides in the model, which was common practice with 2D drawings; define good modeling standards and maintain “digital hygiene”; include phasing in the model; structure the model to reflect and support anticipated bid packages; ensure than the model reflects construction techniques, and avoid using modeling shortcuts; publish the model frequently to ensure that everyone has access to the latest version as close to real time as possible; and test the model early and often for interoperability, which is still an issue; when sending the model, accompany it with screenshots so that the recipient knows what the model is supposed to look like. This was certainly a very helpful and concise best practices list that would very beneficial to any construction firm looking for guidance on implementing BIM, not just for building enclosures but for the entire building.
The next presentation was by Rick Khan of Mortenson Construction, which was one of the earliest construction firms to take the lead in implementing BIM (see the 2006 articles, “2006 2nd Annual BIM Awards” and "BIM Symposium at the University of Minnesota"). At the BIMForum, we saw how Mortenson is using 3D modeling applications to create “virtual mockups” of building enclosures which provide a cost-effective and practical solution to address challenges ranging from the enclosure detailing solutions, subcontractor sequencing, quality inspection, and prefabrication. A virtual mockup is not just a single view of a larger BIM model; on the contrary, it is a stand-alone, highly detailed, 3D model of a specific element or system of the building. The detail level is at Level 400, as defined by the AIA. The virtual mockup is really a 3D shop drawing—it is suitable for construction and allows coordination between the design and construction teams (see Figure 4). Mortensen uses these virtual mockups for high-risk planning, integrated work planning, construction sequencing, and team communication and collaboration.
Figure 4. The use of virtual mockups in detailed 3D shop drawings by Mortenson Construction. (Courtesy: Mortenson).
While the company still uses actual physical mockups in some situations, especially for testing, there is a limit to how many of these it can create, both practically and financially. For the cost of one physical mockup, more than four virtual mockups can be created, making them much more viable. It is interesting to note that the virtual mockups do not necessarily need to be created using a BIM application—Mortensen actually uses SketchUp to model its virtual mockups (see Figure 5). The BIMForum presentation concluded with some examples of projects in which Mortenson used virtual mockups to address various issues, including the simulation of scaffolding for sequencing and safety planning, and the modeling of expansion joints in a roof to identify risk areas prior to construction.
Figure 5. The use of SketchUp to create virtual mockups. (Courtesy: Mortenson).
Technology Updates from Tekla and Beck Technologies
As mentioned earlier, the BIMForum also included some “rapid-fire” presentations from technology vendors highlighting key updates and new product releases. The most exciting of these came from Tekla, which used the BIMForum to announce a brand new application for model-based collaboration called Tekla BIMsight. It allows anyone on a project team to combine and review building information models from all team members. These models can be checked using clash management routines, and tools are available to manage and assign these clashes. While the IFC format is intended to be the primary mechanism for importing models, Tekla BIMsight also supports the DWG and DGN file formats. From the demo that was given at BIMForum, the application seemed very intuitive and easy to use (see Figure 6). You can create a Home view and additional views that are saved in thumbnail tabs for quick access; you can add dimensions, comments, and markups to any view of the model; sectioning tools are available for creating section views of the model; specific element or element categories can be made visible while hiding all other elements; and different elements can be assigned to specific team members or disciplines. The entire session, including all the models and any added markups, comments, saved views, and so on can be saved as a single package for easy transmittal to other team members. In short, Tekla BIMsight offers many of the capabilities that Navisworks currently provides. It also handily beats Navisworks from a cost perspective—Tekla BIMsight is completely free! It is available for download at http://www.teklabimsight.com/.
Figure 6. The user interface of the new Tekla BIMsight, and a clipped view of a model brought into the application. (Courtesy: Tekla).
Beck Technologies was also at hand to share some recent innovations in its DProfiler application, which is a “macro” BIM software targeted towards the planning and conceptual design phase to get an accurate cost estimate of a proposed design. (For a detailed overview of the application, see its review published in AECbytes in 2008.) DProfiler now supports construction sequencing and has a new Revit plug-in which allows DProfiler models to be opened in Revit and used for further design development (see Figure 7). Currently, the plug-in works only one-way and cannot be used to take Revit models into DProfiler. While DProfiler already has IFC export capability for connecting to downstream applications, the IFC did not work very well for Revit, which is why the plug-in is a significant development for connecting DProfiler’s macro-BIM to a more mainstream BIM application for fleshing out the conceptual design into a detailed building model.
Figure 7. The new Revit plug-in that allows a DProfiler model to be brought into Autodesk Revit. (Courtesy: Beck Technologies).
This wraps up Part 1 of the AGC’s BIMForum highlights. The remaining presentations and technologies updates that were featured in last week’s event will be discussed in Part 2, which will be published next month.
About the Author
Lachmi Khemlani is founder and editor of
AECbytes. She has a Ph.D. in Architecture
from UC Berkeley, specializing in intelligent
building modeling, and consults
and writes on AEC technology. She can be
reached at email@example.com.