Dynamic responses test analysis of high-speed railway bridges under earthquake action

Taking the high speed railway bridge structure which is about 195 km from the Jiuzhaigou earthquake epicenter as research object, the dynamic response characteristics and earthquake warning time of the bridge structure under the action of earthquake are analyzed, and the measured data are compared in time domain and frequency domain under the action of earthquake and multiple unit train. The results show that under the action of shear waves, the bridge structure dynamic response rapidly increase, the maximum value under shear wave is about 2 to 5 times of that under pressure wave. At the bridge, the pre-seismic allopatric early warning is about 50 s, on-the-spot seismic P-wave early warning is about 15 s. Under the action of earthquake, the bridge structure is dominated by the low frequency and overall transverse vibration of the high pier, and the transverse vibration value is larger than the vertical vibration value. Under the action of earthquake, the maximum lateral amplitude of the pier top is 43 times that of the multiple unit train, and the vertical amplitude of beam body is positively correlated with the span of bridge. Because the multiple unit train directly on the bridge, the transverse and vertical acceleration of the beam body are greater than the seismic effect. Before and after the earthquake, the comparison of bridge vibration parameters under the action of multiple unit train shows that the bridge structure has no abnormal changes in its working state. © 2021, Editorial Board of Journal of Vibration Engineering. All right reserved.