Integrated Steel Design

To Help Save Time, Structural Engineer Wears Harder Hat, ENR, February 2, 2004, describes Tacoma Washington's use of innovative CAD modeling and fabrication techniques to preorder structural steel for the 279,000 square foot Mt. Tahoma High School. On this project, engineers Putnam Collins Scott Associates developed a digital three-dimensional object based model from which steel detailing and fabrication could proceed. This process effectively removed steel procurement and detailing from the project's critical path and shaved close to three months off of the project's construction schedule.

The ENR article discusses both the risks and potential benefits of these so-called integrated steel design (ISD) techniques. On the Mt. Tahoma High School project, they were highly successful. In addition to reductions in the construction schedule, the engineers claim that there were only 13 RFIs related to structural steel (an unusually low number for a project of this size); of over 2900 anchor bolts only four for one base plate required modification; and of over 15,000 bolted connections, there were no mismatches.

These techniques also create new risks. With ISD, the owner's design team takes responsibility for steel detailing, instead of the general contractor and its suppliers. Additionally, with ISD, steel detailing information flows directly from the design model to the fabricator, without separate review by the general contractor or steel fabricator. This requires a steel designer sufficiently knowledgeable regarding steel fabrication and erection.