Seismic Performance Analysis Of Long Continuous Rigid Frame Bridge With High-Piers

Bridge engineering has played the role of a link in the communication betweenregions, especially in western China, the high mountains, deep valley and the ruggedterrain make bridge engineering account for a large proportion in the traffic and road. Aconsiderable part of west is earthquake-prone area, destruction of bridge structure willresult in the difficulty of relief work and huge casualties and economic loses. Thereforeit is necessary to study the seismic performance and failure process of long continuousrigid frame bridge with high-piers along to the construction of these bridges to provide areference for the type of the bridge seismic and earthquake-reduction design. Accordingto the seismic response characteristic and seismic performance of high-pier andlong-span bridge under uniform and multi-support excitation, the main research of thispaper are as followed:(1) Input multi-support ground motion for the large-span bridge. Ground motion input isthe key problem of seismic response analysis; Along with the increase of the span,spatially variability of earthquake should be considered while inputting the groundmotion. According to the local soil condition and span of the high-pier andlarge-span bridges, this paper will simulate the multiple-support ground motion.(2) The analysis methods of multi-support excitation are summarized. This paper willsummarize the analysis methods of multi-support excitation and solution methods ofdynamic equilibrium equation of multi-support excitation when inputtingdisplacement time history.(3) Study on the influence spatially variability of earthquake to seismic response of thehigh-pier and large-span bridges. The high-pier and long-span continuous rigidframe bridge will be separately carried on seismic response analysis of uniformexcitation, multi-support excitation only considering travelling wave effect,multi-support excitation considering local site soil effect and multi-supportexcitation and compare the results of uniform excitation with the other situation.The results show that: uniform excitation input will overestimate the most internalforces and underestimate shear of pier bottom; compared uniform excitation withthe travelling wave effect and multi-support excitation, uniform excitation is moreunfavorable to the seismic response analysis of long continuous rigid frame bridgewith high piers. (4) Influence of structure model parameters to the high-pier and large-span bridges.Five bridge models with different pier heights and cross numbers are carried onuniform and multi-support excitation, compared the results we get: the higher thepiers are, the bigger the internal forces are; the more the cross number is, the smallerthe internal forces are; the pier-bottom shear of irregular girder bridges issignificantly greater than the one of regular girder bridge.(5) Study on the failure process of the high-pier and large-span bridges under theuniform excitation and multi-support excitation. Choose different earthquake groundmotions to carry on uniform and multi-support excitation for the bridge model withincremental dynamic analysis method. Comparison the process of the destruction,maximum of internal forces and displacements between uniform excitation andmulti-support excitation, we can get that to yield or to ultimate state of each pierfirst occur in the top section; different ground motion and different excitations causedifferent failure process and the maximum internal forces.