Optimal Design of Seismic Protective Devices for Highway Bridges Using Performance-Based Methodology and Multiobjective Genetic Optimization

Abstract

This study investigates the effectiveness and optimal design of protective devices for the seismic protection of highway bridges. The Painter Street Overcrossing is seismically redesigned with protective devices. Component-level fragility functions are first derived by probabilistic seismic demand analysis using nonlinear time history analyses that include soil–structure interaction effects and ground motion uncertainties. The bridge repair cost ratios are then derived using a performance-based methodology and the associated component failure probability. Results of the comparison of two initial protection designs show that the bridge repair cost ratios provided an efficient evaluation of the protective devices. Subsequently, a multiobjective genetic optimization method utilizing the Pareto optimal concept is employed to identify the optimal design parameters of protective devices for six design cases with various combinations of isolation bearings and fluid dampers. Finally, the repair cost ratios of the bridge with optimally designed protective devices are evaluated. The results show that these optimal devices are able to minimize the overall damaging potential of the bridge, hence validating the optimal design procedure as a practical method for selecting protective devices.