Issues in the Prediction of Inelastic Behavior in Bridges during Earthquakes

Abstract

With the continuing development of displacement-based and performance-based seismic design principles in the bridge engineering community comes the need to address issues that have historically been omitted from, or else treated in a vague manner within, bridge design specifications. It is likely that future design provisions will lead engineers to conduct more refined analyses compared to those currently adopted in some cases. This paper discusses four areas in the prediction of inelastic behavior in bridges, two on the capacity side and two on the demand side. On the capacity side, (1) choice of element type, force based or displacement based, and (2) effects from geometric nonlinearities are discussed. On the demand side, (1) differences between building design spectra and bridge design spectra are discussed, and (2) issues related to viscous damping levels adopted for nonlinear analysis are brought to the attention of practicing engineers.