Seismic performance comparison between direct displacement-based and force-based design of a multi-span continuous reinforced concrete bridge with irregular column heights

Abstract

North American bridge design codes, e.g., Canadian Highway Bridge Design Code and AASHTO 2007, follow forcebased design (FBD) method, which is focused at the target force resistance capacity of the structure. Displacement-based design (DBD) method, on the other hand, aims to ensure a target maximum displacement of the bridge during earthquakes in a specific zone. In this study, bridges with irregular column heights have been designed according to DBD and FBD (as per Canadian standards and AASHTO 2007) considering seismic loading. Subsequently, seismic performances of the bridges designed with the two different methods have been compared by conducting nonlinear dynamic analyses in the longitudinal direction. Maximum and residual displacements and energy dissipation capacity are used as performance indicators. This study outlines the necessity of possible modification in the current Canadian seismic design standards as well as DBD for bridges with irregular column heights.