Experimental and numerical study on isolated simply-supported bridges subjected to a fault rupture

Abstract

To investigate the effects of fault crossing on the seismically isolated bridges, shake table testing was conducted on a 1/10 scaled two-span simply-supported bridge model isolated by lead rubber bearings (LRBs). A synthetic fault rupture, consisting of low- and high-frequency simulations, was used to excite the test model from low to high amplitude. Test results revealed that lead rubber bearings are effective in protecting the girders and the piers of the bridge subject to fault rupture, but at the cost of large peak and residual bearing deformation or even the failure of LRBs. The bearings at near fault (NF) span are more susceptible to fault rupture than the crossing fault (CF) span because the participation of longitudinal response compensates the transverse seismic demand of the bearings at CF span. Two numerical models were constructed with differing modeling consideration of LRBs: a sophisticated one using Bouc-wen model and a simplified one using Bilinear model. Both numerical models were able to predict the behavior of test model equally well before the failure of the bearings, validating that the existing nonlinear analytical techniques are adequate to estimate the seismic response of bridges subjected to a fault rupture.