Assessment and mitigation on near-fault earthquake wave effects on seismic responses and pile-soil interactions of soil-pile-bridge model

Abstract

A 1/70-scale soil-pile-bridge model was designed and constructed according to an extremely long-span cable-stayed bridge with a 1400 m-main span. Shaking table tests were performed to estimate the effects of the near-fault earthquake waves on the seismic responses and pile-soil interactions of the bridge model under near-fault and far-field earthquake waves in the longitudinal direction. A three-dimensional analytical model was established to represent the test results and track the response variations resulting from the near-fault earthquake waves. Finally, both control strategies were numerically studied to decrease the effects of the near-fault earthquake waves on the seismic responses of the bridge model. The results showed that the longitudinal near-fault earthquake excitation significantly increased the acceleration and displacement of the towers and girder, and augmented the curvature and strain at the bottom of the towers as compared to the far-field earthquake excitation, resulting in the bridge model suffering from more severe damage. The near-fault earthquake excitation considerably amplified the pile-soil interaction effects on the seismic responses of the towers and piers. Additionally, the analytical model could approximately represent the test results and reliably take the response variations induced by the near-fault earthquake waves. The elastic cables and supporting piers control strategies could effectively mitigate the effects of the near-fault earthquake waves on the seismic responses the bridge model except for the longitudinal acceleration and vertical displacement of the girder, preventing the towers from experiencing more significant damage.