Nonlinear FE model updating and reconstruction of the response of an instrumented seismic isolated bridge to the 2010 Maule Chile earthquake

Abstract

Nonlinear finite element (FE) modeling has been widely used to investigate the effects of seismic isolation on the response of bridges to earthquakes. However, most FE models of seismic isolated bridges (SIB) have used seismic isolator models calibrated from component test data, while the prediction accuracy of nonlinear FE models of SIB is rarely addressed by using data recorded from instrumented bridges. In this paper, the accuracy of a state-of-the-art FE model is studied through nonlinear FE model updating (FEMU) of an existing instrumented SIB, the Marga-Marga Bridge located in Vina del Mar, Chile. The seismic isolator models are updated in 2 phases: component-wise and system-wise FEMU. The isolator model parameters obtained from 23 isolator component tests show large scatter, and poor goodness of fit of the FE-predicted bridge response to the 2010 Mw 8.8 Maule, Chile Earthquake is obtained when most of those parameter sets are used for the isolator elements of the bridge model. In contrast, good agreement is obtained between the FE-predicted and measured bridge response when the isolator model parameters are calibrated using the bridge response data recorded during the mega-earthquake. Nonlinear FEMU is conducted by solving single- and multiobjective optimization problems using high-throughput cloud computing. The updated FE model is then used to reconstruct response quantities not recorded during the earthquake, gaining more insight into the effects of seismic isolation on the response of the bridge during the strong earthquake.