Seismic Performance Evaluation Of Isolated Continuous Beam Bridge And Reinforcement Research Of SMA On The LRB Based On Endurance Time Method

China is in an earthquake-prone area and has a large number of bridges.In the future,the construction of bridges has a very wide development trend.That Cognizing the Damage Behavior and Change Law of Bridge under Strong Earthquake by Science and Technology,grasping the mechanism of bridge failure,and based on this,developing the bridge's seismic design theory and damage control engineering measures,it has important academic value and social significance for improving the seismic capacity of our Bridges in China.As a new seismic analysis method,the Endurance Time Analysis Method can not only consider the influence of high-order vibration modes,but also can predict the seismic performance of structures under different intensity ground motions in a short time(only one time-history analysis is required).In addition,shape memory alloys(SMAs),a new type of smart material,have excellent energy dissipation and self-resetting capabilities.If it is applied to isolated bridges,it will greatly improve the seismic isolation performance of the bridge and reduce the large deformation of the superstructure under earthquake action! The main research contents of this article are as follows:1.This article introduced the basic concepts of seismic time history analysis method,The calculation principle,formula and solution method of earthquake-resistant time history curve in seismic time history analysis method are briefly introduced.Finally,the constitutive relationship and mechanical properties of shape-memory alloy(SMA)were described.The seismic isolation performance and working process of new-type SMA-lead rubber shock-isolation bearings were preliminarily introduced.2.Based on the spectrum of the standard response spectrum specified in the <Guidelines for SeiSmic DeSing of Highway Bridge>,three ETAFs with duration of 30 s were optimized and the conversion formula of the equivalent earthquake-resistant time in IDA analysis results was introduced.The elasto-plastic single free system was analyzed by ETM,and compared with the results of IDA analysis of seven actual ground motions,the validity of three seismic time-history methods was studied.3.Taking a five-equivalent earthquake-isolated continuous beam bridge in western China as a case,we introduced the use of OpenSees to establish a finite element model of a seismically isolated continuous beam bridge,and Based on the performance of the bottom curvature ratio,the displacement ratio of the pier top and the shear strain of the isolation bearing,we divide the damage status of the bridge.Finally,the seismic response of the bridge under ETAFs,far-field vibration and near-field vibration was calculated respectively,and a comparative analysis was performed to verify the high efficiency and accuracy of the ETM in the seismic analysis design of isolated bridges.4.Introduce the arrangement of SMA on isolation bearings and how to simulate the new bearing constitutive relation,Seismic Performance Evaluation of Fifth-class Continuously-isolated Girder Bridge with SMA-Lead Rubber Bearings Using ETM,and comparing with the results of ETM of ordinary isolated bridges,to study the effect of SMA on the performance of lead core isolation bearings.