The New Tacoma Narrows Suspension Bridge: Construction Support and Engineering

From the very beginning of the design phase, construction engineering considerations were already being interjected into the project. The purchase order for the steel supply and fabrication was in place early, and fabricator input was sought and included throughout the design process, including fabricator presence at nearly all Task Force Meetings, with the intent of designing-in features that made fabrication and erection efficient. For shipping considerations, the segment stacking method, estimation of cumulative fatigue damage, and the use of passive damping and temporary connections between segments were considered important factors. The cumulative fatigue damage sustained during shipping was limited to 10% of the final Design fatigue threshold. Detailed studies were performed to evaluate the structural performance of major bridge components (main cables, suspenders, main load carrying superstructure elements, towers) under various erection stages, including dynamic and buffeting wind loadings for critical erection stage configurations. Detailed wind tunnel and mathematical models representing significant components of the bridge and temporary equipment, with their respective masses, were employed. This paper chronicles the construction support and engineering efforts performed for the Tacoma Narrows Constructors to streamline and integrate the design and construction of this unique structure.