Study On The Seismic Response Of A Continuous Rigid Frame Bridge With Long Span And Ultra-High Piers

In recent years, many continuous rigid frame bridges with long span andultra-high piers have been built in the construction booms of expressways inmountainous areas of western China, both the spans and pier height of this kind ofbridges are beyond the current criterions or guidelines for seismic design of highwaybridges, couple with the shortage of relevant seismic damage data that can be used inseismic design of such bridges, we can only make the bridge seismic design refer to theguidelines for general bridges. Therefore, it is practical and urgent to carry out aresearch on seismic response problems of continuous rigid frame bridges with long spanand ultra-high piers, this work will be helpful for seismic performance evaluation andseismic design of such kind of bridges.In this dissertation, the dynamic and seismic response characteristics of HezhangBridge were made according to structural natural vibration characteristics analysis,linear elastic response spectrum analysis and time history analysis with the finiteelement models developed by Midas/Civil and SAP2000software. Second, after thehysteretic model of sections were established, the elasto-plastic seismic responseanalysis and IDA analysis were made by adopting fiber hinge model and bendingmoment hinge model respectively, obtained development patterns and failure mode ofplastic hinges. The results show that: whatever the incentive direction of earthquakesapplied, the earthquake magnitude for bridge piers are greatly beyond its requiredvalues, the bridge can withstand the seismic load above1.0g, which meets therequirements for bridges against earthquakes well. And we can learn from thedevelopment of plastic hinges and its failure patterns that the plastic hinge at weakersections both at top or bottom of the shorter piers are the first trick to yield and the firstto damage, which can be regarded as key sections in aseismic design of such kind ofbridges.The research results in this dissertation can give reference to the earthquakeresistant analysis and design of other continuous rigid frame bridges that is irregular,with long span and ultra-high piers.