Validating Innovative Design Solutions - Analysis of the Gerald Desmond Bridge Replacement

In 2011, the Port of Long-Beach, in collaboration with Caltrans and LA Metro, awarded the Design and Build contract for the replacement of the deteriorating Gerald Desmond Bridge to SFI Construction (Schimmick / FCC /Impregilo joint-venture). Arup had been lead designer for SFI’s tender proposal, providing structural andgeotechnical engineering, traffic operations analysis, lighting design and civil engineering services. Arup designed an elegant mono-pole stayed-cable solution that met all the project requirements while providing dramatic cost- savings to the Client. The team’s innovative solution earned the judges’ highest ratings for both technical design and price and ultimately won the job. The deployment of advanced LS-DYNA ® analysis capabilities was instrumental in assessing the structural options against the stringent project requirements. The extreme seismic demands of the 1000-year Safety Evaluation Event (SEE) could be addressed by isolating, by means of viscous dampers, the Main Bridge deck from the Towers and by introducing a ground-breaking approach for the design of the ductile hollow-section columns. These innovative solutions, among other particular features of the bridge, required detailed Finite Element modelling and validation through explicit nonlinear time-history analysis. This paper presents some of the key modelling techniques and analyses results that contributed to the successful development of this new landmark.