Reduced scale shaking table test and numerical study on a simply supported bridge crossing fault

Reduced scale shaking table test and numerical study on a simply supported bridge crossing fault

In order to understand the response of a simply supported bridge under the action of a crossfault earthquake, this study investigated a set of 1:81 scale two-span simply supported bridge experimental models. Through small-scale shaking table experiments, we were able to compare the displacement and acceleration responses of such bridges during near-fault and cross-fault earthquakes. In addition, this study established a numerical model for comparison with the experimental results and calculated the corresponding internal force in the bridge column. The experiment used two small shaking tables to simulate near-fault and cross-fault effects using synchronous and non-synchronous inputs. The variables considered included the effect of the seismic stoppers and the direction of fault movement. Nonlinear dynamic time history analysis for displacement-input earthquake forces was conducted using SAP 2000N software. The experimental and simulation results show that the cross-fault effect was mainly reflected in the displacement of the structure. If the displacement is restricted, the internal force of the bridge pier is increased significantly. On the other hand, the dynamic acceleration of the bridge deck is mainly caused by the dynamic effect of near-fault acceleration. The research results also show that if the experiment uses a single shaking table to simulate the cross-fault effect, the calculation of the relative displacements of the bridge is not significantly different from the simulation using double shaking tables；however, the acceleration responses and the internal forces of the bridge pier may be incorrectly estimated.