Non-linear seismic response analysis of vehicle-bridge interactive systems

The intention of this study is to investigate how vehicles on highway bridges affect the seismic responses of the bridges under strong ground motions. Most highway bridge design codes do not consider the live load in the seismic design of highway bridges because of the low probability of the two events of the critical live load and an earthquake occurring at the same time. As a result, little attention has been paid to the influence of vehicle loads on the seismic responses of highway bridges. However, considering the high probability of traffic jams on urban roads, it is preferable to examine and clarify the dynamic interaction effect of vehicles on road bridges while subjected to seismic loads. In this study, the vehicle-bridge-ground motion interactions are realized by combining ABAQUS and MATLAB. ABAQUS provides a GUI environment to establish the numerical bridge model and apply the seismic forces, while MATLAB provides a platform to control the iterations in both time and force increments. As a preliminary study, a simplified 3D pier-beam bridge model loaded with multiple vehicles with two degrees of freedom moving at a constant speed has been considered. When subjected to identical, strong seismic loadings, it was observed that the transverse accelerations of the bridge with moving vehicles are smaller than those without moving vehicles. Further, permanent deformation occurs after earthquakes because of yielding at the bottom of the pier; it was observed that the permanent deformations of the bridge with moving vehicles tend to be smaller than those without moving vehicles.