钢筋混凝土公路连续梁桥地震风险与抗震可恢复性分析

ABSTRACTIn recent years,many earthquakes were found to contain the near-fault effectseismic record,bringing all kinds of engineering structures,including bridges,intensedamage,causing wide attention in engineering seismic field.Due to the effects of thehigh energy pulse,it has been proven that bridges in near-fault zones face the higherseismic risk.In this paper,seismic risk analysis method of near-fault bridge structureis introduced and applied to research the effects of pulse on the seismic risk ofnear-fault RC bridge structure.The main results and conclusions are as follows:(1)Considering the uncertainties of the bridge structure and ground motion,adopting the appropriate damage index,choosing the spectral acceleration at the firstperiod of the structure as the ground motion intensity measure,probabilistic seismicdemand model of the bridge structure are established.Then the seismic fragilitycurves of bridge structure are obtained.The results show that the curves of bridgecomponents and system under near-fault pulse-like ground motions are very close tothose under near-fault non-pulse-like ground motions.(2)The transcendental probabilities of various damage levels of bridge structureunder near-fault pulse-like and non-pulse-like ground motions for the givenmagnitude,the fault distance and field condition,were calculated based on thefragility analysis and the modified ground motion prediction equations(GMPEs).Theresults show that the transcendental probabilities of various damage levels of bridgecomponents and the bridge system under near-fault pulse-like ground motion aresignificantly greater than those under the near-fault non-pulse-like ground motion.And the expand coefficients of damage probability (the ratio of damage probabilityunder pulse-like and non-pulse-like ground motion)decrease with the increasing ofmoment magnitude,increase with the increasing of fault distance and (thetime-averaged shear-wave velocity from the surface to 30 m).(3)Taking a single site near the strike-slip faults as an example,considering thepulse effect,the seismic hazard analysis is done to calculate the acceleration responsespectrum and the seismic hazard curves.The result shows that the seismic hazardsignificantly improved due to the pulse effect.(4)Seismic risk analysis of the bridge was done based on the seismic hazard