Research On Seismic Isolation Design For Long-span Continuous FPB-LRB Joint Bridges

The main features of earthquake disasters in China are high frequency,large intensity,shallow source and heavy disaster.These characteristics put forward higher requirements to the seismic isolation of bridges in China.The current industry standard "Guidelines for Seismic Design of Highway Bridges"(JTGTB02-01-2008)mainly recommend the use of Friction Pendulum Bearing(referred to as FPB/FPS)and Lead Rubber Bearing referred to as LRB)to design the bridge of seismic isolation,but the isolation principle of FPB bearings and LRB bearings are different.This article combined with the characteristics of large span bridges in China Southwest area,reference a large span continuous beam bridge as the engineering background,had the help of Midas civil software,used the nonlinear time schedule analysis method based on the seismic isolation of FPB bridges and LRB bridges,proposed the thought of FPB-LRB seismic isolation,and further researched the FPB-LRB bridge's,while the LRB bearing location in the FPB-LRB bridge in the optimization study,the study found:(1)Based on the influence of FPB bearing friction coefficient and LRB bearing on earthquake displacement peak ? pier bothom force and integrated vibration isolation rate,this article inferred that FPB bridge and bridge have better isolation with FPB bearing friction coefficient of 0.03 and LRB bearing lead rate of 100 mm.(2)Through the comparative study of FPB bearing friction coefficient is 0.03 FPB and LRB bearing bridge lead core diameter 100 mm LRB bridge FPB bridge shows that compared to the self recovery performance of LRB bridge is better,compared to the FPB LRB bridge bridge has higher isolation efficiency reduction.(3)The FPB-LRB bridge is constructed by replacing the corresponding position of the FPB bearing with two LRB bearings in the FPB bridge.The influence of the LRB bearing placement on the isolation performance of the FPB-LRB bridge is systematically analyzed.In the edge of the bridge on the bridge is not significant earthquake,the LRB bearing only located in the pier on the pier,on the cloth with LRB support bridge pier isolation effect is the best,but the two main pier force imbalance is not conducive to Bridge seismic,the LRB bearing separately located in the two main pier,the pier force more reasonable,the bridge is better than the isolation effect.(4)By comparing the FPB bridge,LRB bridge and FPB-LRB bridge of the seismic isolation performance,FPB bridge both the self recovery characteristics of FPB-LRB bridge andthe LRB bridge of high seismic isolation performance.