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| Design and construction teams Washington Nationals Ballpark Owner: DC Sports & Entertainment Commission Architect: HOK/Devrouax & Purnell, PLLC Contractor: Clark/Hunt/Smoot Joint Venture Structural engineer: Thornton Tomasetti, Inc. Yankee Stadium Owner: New York Yankees Architect: HOK Sport + Venue + Event Development manager: Tishman Speyer Properties Preconstruction services: Turner Construction Structural engineer: Thornton Tomasetti, Inc. New Meadowlands Stadium Owner: New York Jets and Giants Client/Architect of Record: 360 Architecture Inc.; EwingCole Contractor: Skanska USA Structural engineer: Thornton Tomasetti, Inc. |
These are impressive productivity features. Yet they are just individual aspects of BIM’s most impressive capability: It provides a powerful platform for sharing design and construction information among all project team members, including the design team, the owner, and contractors.
BIM replaces what was once a sequence of paper document issues with an integrated delivery process that benefits all team members. Traditionally, project members were individual "silos" ― operating independently ― but BIM encourages better and more frequent collaboration.
When it comes to how structural engineers deliver stadiums, arenas, and even small projects, sharing intelligent 3-D information early and often changes the game. Not only does BIM assist the project members in operating from the same game plan, but it helps each player more quickly understand the contributions of others’ expertise in accomplishing the project.
In short, by sharing the building information model with all team members, project members are not only on a team, they truly play like a team. Owners, for example, can see exactly what they will get ― not a 2-D approximation that leaves out essential details, but a realistic depiction that allows them to commit to decisions earlier. Engineers can estimate quickly how design changes will impact quantities and schedule. Architects can see the 3-D structure and verify that design goals are being met. Contractors can test staging and erection strategies before placing the first steel order. Fabricators and detailers can bid more aggressively because they receive an accurate bill of materials along with the enhanced 3-D representation of details.
Sharing a building information model is a "win-win" for the whole project team. What’s more, BIM’s ability to visually represent the structure—including details and intelligent attributes—greatly aids each team member’s participation. This is particularly true when designing stadiums, for instance, because engineers must perform a delicate balancing act to satisfy project needs. On one hand, they must take care to incorporate the architect’s design goals into the structural design. On the other, they must ensure that the documents they transmit to contractors include the information needed to build the structure. BIM makes that balancing act easier to manage since everyone can see the 3-D representation of the "virtual" structure before it is built and share the same smart information.
The BIM difference
To understand why BIM is so powerful, consider how it works. Building information models are the "buckets" that contains smart information. Each element of the model is a separate object that has specific information (attributes or data) associated with it. Besides the specific geometric information, this data often includes attributes such as size, material grade, finish, and even LEED sustainability information. This embedding of intelligent information allows project participants to harvest information of interest, such as, for quantity take-offs. In fact, because the data improves as the design matures, quantity take-offs can be performed easily during design, as well as during the bidding and construction phases.
Also, BIM objects can have relationships with one another, called parametrics. Imagine, for example, a truss supported by four columns. The truss "knows" it is attached to the columns. Change the size of the truss and the columns’ geometry will move with it to accommodate the change. Similarly, global changes to geometry—such as changes to floor-to-floor heights or grid line adjustments—will also change every member associated with that floor or grid.
This type of intelligence allows structural engineers to leverage parametrics for rapid generative studies of geometry. These studies can show how changes to geometry affect stress levels and forces in materials. They are powerful tools when used correctly.
Today’s engineers are using BIM for the following:
Visualization—Building information models provide 3-D representations of the structure. Users can see beams, columns, slabs, foundations, connections, and—if detailed—even how far bolts will extend from a beam.
Clash detection—Because a building information model knows each object’s location, orientation, and dimension, it can determine when two or more objects occupy the same space. BIM users can run clash detection checks during the design phase to highlight problems visually. This produces better coordination of the design team information before construction begins.
Smart (parametric) changes—With BIM, changing one part of a model’s structure automatically updates adjoining pieces. This makes it possible to study multiple approaches quickly and rapidly implement design changes.
When BIM data is shared with contractors, the benefits to them include the following:
Improved bidding—Contractors and suppliers are never entirely certain that they know everything about the work on which they are bidding. If they could send out bid packages that include 3-D information with embedded intelligence, suppliers and subcontractors would gain a quicker understanding of the project, resulting in more accurate bidding.
Improved understanding — Contractors and suppliers can more easily see the complexity and scope of a project in 3-D, thus reducing misunderstandings that can happen with 2-D drawings.
4-D and 5-D scheduling—Contractors can add time (4-D) and cost (5-D) to models to visually represent construction sequences and cash flow analysis.
Washington squeeze play
BIM helped the Washington Nationals professional baseball team meet an extremely aggressive schedule (compounded by funding delays) to complete its 41,000-seat ballpark in the nation’s capitol in time for opening day this season. The project was especially complex since it configured concourses and seating decks into distinct "neighborhoods" that have their own identity and viewing experience.
The project team used BIM to expedite the schedule. Sharing the model with the contractors shaved months off the schedule because fabricators did not have to build their own model based on paper drawings. Tekla Structures, the BIM software used on the project, helped keep the project moving forward.
With time so tight, the structural engineers could not deliver one work package for the entire project. Instead, they divided the stadium into 10 segments and delivered each segment as they completed it. The individual parts were combined into a master building information model by the fabricator.
The structural engineers used Tekla to model the main steel members and the preliminary connection details. Then they handed off the model to the fabricator, who used it for steel take-offs and to complete the detailing. This sharing of the model gave the fabricator a head start in understanding the engineering requirements and in creating the advanced bill of materials.
By leveraging the Tekla model, the contractor was able to order steel three months earlier than usual. Also, each segment was completed about one month early because the fabricator could use the data supplied by the Tekla model, as opposed to performing manual take-offs from traditional 2-D engineering drawings. Equally important, during the design phase the engineers accurately depicted how the details would look in the as-built stadium, resulting in smoother design approval by the architect.
Everyone contributed his or her expertise, and the details required for successful completion of the project were accomplished in a timely manner. Fabricators double-checked that all prefabricated structures would fit on a truck. Contractors and suppliers optimized staging, always an important consideration in urban settings with limited space. Engineers, fabricators, and contractors worked out erection sequences before deciding where to splice the structural steel members. All of this work was expedited and enhanced by the use of BIM.
Construction went smoothly, especially considering the tight schedule. The stadium opened on time to a sell-out crowd.
Yankees score
The new Yankee Stadium, slated to debut in the 2009 season, showcases the aggressive use of BIM. At $1.3 billion, it will be one of the most expensive stadiums ever built. The new structure for the New York baseball team will take the place of one of sports’ most venerable pieces of real estate replacing the old Yankee Stadium—affectionately known as "The House that Ruth Built" as a tribute to the most famous Yankee, Babe Ruth. Naturally, every detail has to be perfect.
The project team took full advantage of BIM: visualizing fabrication and construction details, detecting clashes, creating bills of materials, and ordering steel. The Yankee management was especially concerned with the signature steel frieze that rings the top of the canopy, which is almost an icon of the Yankees’ brand. It is a replica of the original copper frieze that contractors tore down during the 1974-75 renovation of Yankee Stadium. BIM helped the project team ensure accuracy of the frieze’s aesthetics and geometry by modeling it in 3-D to gain approval from the architect and the owner.
The project team also provided building information models to mechanical, electrical, and plumbing subcontractors. Instead of overlaying 2-D drawings of wires, pipes, and HVAC systems, the subcontractors quickly referenced the model to locate their space and scan for clashes.
BIM also changed the nature of progress meetings. In the past, a dozen professionals would bring their drawings into the room, compare their schematics with the others, and make mark ups of changes. Trying to decipher those notes after the meeting always proved to be a real challenge.
The use of BIM has changed that process entirely. Everyone in the room powers up a laptop and opens the same model. When the model shows a clash, team members decide together how to resolve the issue. If discrepancies arise, they can call up the history of all previous decisions to review the solutions they had approved. When they return to their offices or the jobsite, team members have the same model and the same solutions.
Thanks in part to BIM, the Yankee Stadium project is on target to welcome fans on opening day in 2009.
Touchdowns in the meadowlands
The new Meadowlands Stadium will be home to two New York-based professional football teams, the Jets and Giants, when it opens in 2010. The 700,000-square-foot facility being built in East Rutherford, N.J., is not only big, but complex. Behind its horizontal aluminum louvers will be 82,500 seats (including 10,000 club seats and 200 suites), four 40-feet-long by 130-feet-wide video scoreboards, and 2,500 video screens.
The stadium’s size, complexity, and $1.7-billion cost create major concerns about construction logistics. The project team uses BIM to improve productivity. Early on, engineers teamed with architects and contractors to lock in the design so they could order materials ahead of expected price increases. They also collaborated with contractors and the trades to resolve potential construction issues before the first cranes arrived on the site.
Overall, BIM enabled the steel detailer and fabricator to start the connection detailing as soon as the steel members were released for mill order. And, BIM helped curtail the shop drawing preparation time. BIM also improved the coordination of precast stadium units and identified any conflict with structural steel or other trades early on so that the team could avoid any field work. The contractor and owners have been able to control costs and build ahead of schedule so the owner can potentially begin earning revenue sooner.
Slam dunk in Brooklyn
BIM is also playing an essential role in the new Brooklyn Nets Arena, the future 20,000-seat home of basketball’s New Jersey Nets. The Brooklyn Arena will feature an ambitious Frank Gehry design. Here, BIM’s ability to visualize the complex and unusual geometry is critical to understanding the architect’s design intent. The structural model is also one of the project’s deliverables and will help accelerate the steel procurement and shop drawing schedule. In addition, the final steel model with the connections can be inserted back into the architect’s overall model for clash checking and coordination. The use of BIM on this project improves the process for the entire team.
Game changer
BIM has clearly evolved into a game-changing technology for structural engineers, and indeed, the entire design and construction industry. The benefits most typically discussed when using a building information model, such as visualization and clash checking, are just the beginning. Structural engineers can use BIM to increase their productivity and help increase the productivity of the entire project team.
To share models ― not only with fellow design team members, but also with contractors ― is a big step toward unlocking the full potential of BIM. The BIM process, not the BIM software, is what truly changes the way engineers deliver stadiums. This takes an early commitment, generally starting during the design phase. Legal hurdles can be overcome, models must be created accurately and be complete to a point of being useful downstream, and all team members must bring to the table the right collaborative spirit.
With this approach, structural engineers will attain the next wave of BIM benefits.
Principal Mike Squarzini, Vice President Mark Tamaro, Principal Anjana Kadakia, Principal Erleen Hatfield, and Chairman Tom Scarangello are all with Thornton Tomasetti. They can be reached at the firm’s headquarters in New York at 917-661-7800. Thanks to Donny Beck and Steve Hofmeister for help in preparing this article.
