Resultant Response-based Method for Assessing the Critical Excitation Direction of Horizontally Curved Bridges

Abstract:

Some methods for determining the critical excitation direction of structures regard the response along principal axes of components as the judging criterion, which have some limitations in the practical engineering application. To fill in this gap, a resultant responsebased method was proposed. Based on the response spectrum method, formulae for this method were derived. A typical horizontally curved bridge was selected as the case project, and the finite element model for this bridge was built. The critical excitation direction of the bridge was assessed by applying the resultant responsebased method and the results derived from this method were compared with those obtained from the linear time history analyses at multiple ground motion orientations. Results indicate that the resultant responsebased method can comprehensively reflect the variation of mechanical performance of the bridge component with the seismic excitation direction and has advantages of minor computational efforts and higher reliability. When regarding the resultant response as the judging criterion, adopting the excitation directions recommended by the current code for dynamic analyses of curved bridges can satisfy the seismic design requirement of practical engineering.