Seismic Response and Fragility Estimates of Highway Bridges Considering Various Modeling Uncertainty Parameters

Abstract

This paper proposes an alternative seismic assessment framework considering various modeling uncertainty parameters, and investigates their effects on the seismic response and seismic fragility estimates of a case-study bridge. Firstly, sensitivity analyses with the tornado diagram technique are performed to determine the sensitivity of some typical bridge engineering demand parameters (EDPs) to twenty-two modeling related uncertain parameters, and the results indicate that the variability in ten identified critical parameters has significant effects on the bridge EDPs. Subsequently, based on a series of nonlinear time history analyses (NLTHAs) on the sample models generated by using Latin hypercube sampling (LHS) method, comparative studies for the seismic responses of some typical bridge members and the seismic fragility estimates both at bridge component and system levels incorporating different levels of uncertainty are performed, respectively. It is concluded that (1) the uncertainty of the modeling related parameters may lead to the difference in the trajectory of seismic response for a given bridge member, whereas the variation of the peak value of such seismic response may due to the joint actions of the uncertainty of ground motions and modeling parameters; (2) the inclusion of only ground motion uncertainty is inadequate and inappropriate, and the proper way is incorporating the uncertainty in those identified significant modeling parameters and ground motions into the seismic response and seismic fragility assessment of highway bridges.