Characteristicresponse analysis of bridge piers under multi-pulse near-fault earthquake excitation

The response patterns of bridge piers under the excitation of multi-pulse near-fault earthquake were investigated. 17 out of 22 sets of earthquake motions were characterized as pulse-like near-fault motions utilizing the multi-pulse analysis method and relevant parameters were determined meanwhile. The corresponding 17 sets of acceleration time histories whose spectra were compatible with the target spectrum were obtained by virtue of the superposition of time domain wavelet strategy. The effectiveness of the matching results were validated by comparing the time histories and elastic response spectra before and after match process. Four bridge piers were modeled by using OpenSees, and the reasonability and accuracy of the four piers model were validated throught the modal analysis and pushover analysis. The matched time histories were taken as the earthquake excitations and the characteristic responses of piers were analyzed. The analysis results indicate that the matched time histories and corresponding response spectra agree well with the target spectrum, and the relative error of the displacement ductility capability between the results of finite element analysis and experiments locates within 5%. The seismic input energy in the horizontal direction corresponding to the strongest pulse energy is greater than those in other horizontal directions, and the seismic demand of bridge piers in that direction is the greatest. From the aspect of displacement ductility demand, the direction of the strongest level of input energy should be considered, and it is dangerous to represent the seismic input by single pulse waveform, hence multiple pulses mode should be adopted instead of single pulse mode. © 2017, Editorial Office of Journal of Vibration and Shock. All right reserved.