Real-time hybrid simulation for investigating the seismic response of a bridge isolated with lead rubber bearings

Abstract

This study investigates the seismic response of lead rubber bearings (LRBs) under constant and time-varying axial forces using real-time hybrid simulation (RTHS). Although shake table testing can provide realistic seismic responses, it is often expensive and quite challenging for large-scale structures. RTHS, however, offers a cost-effective alternative by experimentally testing only the structural component of interest while analytically modeling the remaining structure. With the use of an advanced real-time force control method, this study implemented RTHSs for a bridge isolated with two LRBs, where the LRBs are subjected to various constant axial forces due to self-weight as well as time-varying axial forces induced by vertical ground motions. The lateral response of LRBs was found to be significantly influenced by the magnitude of constant axial force, highlighting the importance of incorporating the effect of axial force due to self-weight into numerical simulations. Additionally, it is crucial to satisfy the axial force boundary condition when conducting RTHS or cyclic loading tests to obtain more reliable test results. On the other hand, the time-varying axial force generated by the vertical vibration of the bridge due to vertical ground motions has a limited impact on the lateral response of LRBs.