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Despite liability issues, A/E/C teams are benefiting from sharing their 3D models

By Michael Bordenaro

Realizing the impossible

Idaho Place is on hold until Spring 2003, so the structural-steel fabrication has not been bid, and it is uncertain how much of the 3D model will come into play during manufacturing. However, NBBJ’s design of two 30-foot tall steel staircases for Amgen’s Seattle headquarters has made it through design, engineering, and manufacturing with the assistance of 3D modeling.

 

Computer modeling of steel for Chicago’s Soldier Field renovation assisted the need for complex structural connections to be designed and manufactured in a short time frame. As many as 20 angled and beveled members come together in connections that are smoothly erected in the project’s 16-month schedule. Renderings: Courtesy Wood + Zapata

Amgen, which bills itself as the world’s largest biotech company, wanted to encourage personal interaction among scientists through the use of “communication” stairs that would both foster and be a place for discussion. One stair represents chaos through its cacophony of forms, and the other is modeled on a double helix. Both are self-supporting structural-steel sculptures.

NBBJ architect Robert Leykam created numerous hand-drawn sketches and a 3D computer model in AutoCAD to help communicate the complex geometry of the stairs. He shared 2D AutoCAD drawings with the project structural engineer, KPFF Seattle, which used the drawings to help create a 3D model in its SAP 2000 structural engineering analysis program.

“You could not create a design like this by yourself as an architect, and KPFF could not have done it without the current technology available,” says Leykam. “The connection analysis at welds, test loading diagrams, distribution of uniform loads, and analysis of other scenarios resulted in the use of less steel and less welds than I thought possible, and greatly contributed to the hovering effect of the helix stair.”

Carolyn Weiss, project engineer for KPFF, says, “SAP 2000 provides 3D modeling and dynamic property analysis, so we were able to provide fundamental periods and other data in addition to presenting detailed images of how the stairs would look.”

Leykam used the images to make subtle changes in details impacting the structures, but more importantly, the SAP 2000 3D models were provided to Portland, Oregon–based Columbia Wire & Iron Works, a 100-year-old iron and steel fabricator. However, because of legal implications, KPFF’s 3D model was only used as a check set against Columbia’s model, which was created on SDS2, a structural-steel-detailing software program. Weiss says, “We simply provided it for reference and included a disclaimer saying the dimensions have to be verified, but Columbia used it to make sure their working points were coming out right when they laid out the steel.”