Experimental Research on the Seismic Response of a Continuous Rigid Frame Bridge With High Piers Under Near-fault Pulse-like Ground Motions

To study the effects of near-fault pulse-type (NFPT) ground motions on seismic response of a continuous rigid frame bridges with high piers (CRFB-HP), a 1/15-scale model was designed and fabricated. Then series of shaking table tests were carried out to study the seismic response of the model under the far field ground motions and NFPT ground motions, respectively. The effects of the velocity pulse number (VPN) were mainly discussed. Results show that the first-order vibration frequencies of the model bridge along the longitudinal and transverse directions are relatively small. The seismic response of the model is mainly low frequency response. The seismic response of the bridge model under the NFPT ground motions is greater than that of twice of it under the far-field ground motions. However, the dynamic response of the bridge model under the no-pulse near-fault ground motions is slightly smaller than (0.76-0.95 times as large as) that of the far-field ground motions. The velocity pulse causes instantaneously large displacement response of the model, the peak value is up to 54.8 m. In this sense, the collision between the abutment and the girder or the bearing damage may occur. The VPN has a significant influence on the seismic response of the bridge model, and the influence coefficient of the VPN (AF_w) is between 1.46-5.54. The multi-pulse ground motions may cause larger dynamic response of the model than the others. The double-pulse ground motion has much smaller influence on the dynamic responses of the model bridge. The parameters influence of the NFPT ground motions on the seismic response of the long-period bridges should be considered.