Shaking Table Test Of Isolated Girder Bridge With Steel Damping Slide Bearing

Steel damping composite slide bearing has the advantages of good economy and isolation performance,and it has been gradually applied to small and medium span fabricated girder bridge.However,the bridge with this kind of bearing has not been fully tested under strong earthquake,so that the seismic performance research is inadequate.Based on the shaking table test,a series of studies on the seismic isolation performance,parameter design as well as vulnerability analysis on steel damping slide bearing are conducted in this thesis through nonlinear numerical simulation and theoretical analysis.The main work are as follows:(1)A two span reduced-scale model of simply supported beam girder bridge with continuous deck was designed and used for shaking table test.The isolation effect of plate rubber bearing,high damping rubber bearing and steel damping slide bearing was compared in the study.(2)The finite element model of isolation bridge with three kinds of bearing was built,and finite element calculation results and experimental results were compared.The influences of seismic wave input direction,frequency spectrum characteristics,intensity and duration on seismic response of isolated bridge were discussed in this thesis.(3)The isolation performance and mechanism of steel damping slide bearing were analyzed and the parameter optimization was done for slide bearing.Some suggestions for properly applying steel damping slide bearing in isolated bridges were made.(4)By defining the failure state of steel damping slide bearing,vulnerability curves have been developed according to the reliability probability theory.And the seismic performance of isolated bridge was evaluated from the perspective of seismic vulnerability analysis.The main conclusions are as follows:(1)Seismic isolation performance of the steel damping slide bearing and the high damping rubber bearing is relatively similar under the E1 and E2 earthquake,and both of them are better than the plate rubber bearing regarding this aspect.Under the E2 earthquake,the reduction of acceleration of bridge deck and the internal forces of pier bottom with steel damping slide bearing are more obvious than those with high damping rubber bearing.(2)The isolation effect of steel damping slide bearing under longitudinal excitations is better than that under transverse excitations.The isolation effect of steel damping slide bearing is poor when seismic wave spectrum characteristics are close to the natural frequency of the model.The isolation effect of steel damping slide bearing becomes superior with the increase of ground motion intensity.The longer the seismic wave duration lasts,the more adequate the sliding becomes,and the better the isolator effect of the steel damping slide bearing is.(3)The yield strength,initial stiffness and yielding stiffness ratio have a great influence on the isolation effect of the steel damping slide bearing.The displacement reduction rate of the bridge deck increases with the increase of yield strength and the initial stiffness,and then remains unchanged to a certain level.The displacement reduction rate of bridge deck decreases first and then increases with the increase of yield stiffness ratio,and finally remains unchanged to a certain level.The range of yield strength,initial stiffness and yield stiffness ratio is provided,and the yield stiffness ratio is 0.005?0.015.(4)The steel damping slide bearing will not cause medium damage under the designed earthquake.The steel damping slide bearing may cause moderate damage in the longitudinal and transverse situation,but will not be seriously or completely destroyed.