Stiffness Optimization And Yield Performance Analysis Of Continuous Beam Bridge Pier Under Stationary Random Excitation

At present,the research of structural optimization under random excitation is mainly focused on simple structure,but less on large-scale complex structure.In this paper,take the sum of pier stiffness as the constraint condition,then the stiffness distribution of continuous beam bridge pier in the elastic stage under stationary random excitation is optimized when the hysteretic performance of bearing is considerd.Then the influence of pier plastic parameters on its yield performance is discussed when the plasticity of pier is considerd.The main contents are as follows:(1)Taking a simplified two degree of freedom model of a three span continuous beam bridge as the analysis object,finish the optimization of the pier stiffness of the two degree of freedom model under the stationary random excitation,and the effect of the method on the seismic performance is clarified.The influence of the stiffness ratio of fixed pier and movable pier on the key response of the structure is analyzed,and the influence of the change of site soil parameters on the optimization results is discussed.The influence of the change of plastic parameters on the yield performance of piers is given when the pier yields.(2)The simplified mid span model of continuous girder bridge is established,and the stiffness distribution of piers is optimized.The influence of site soil parameters,horizontal stiffness and plastic parameters of movable bearing on the optimization results and seismic response is analyzed,and the influence law of the change of relevant factors on the optimization results is given.Then,the fine model of three span continuous beam bridge is established and analyzed.According to the strength grade of seismic action,two kinds of seismic actions in longitudinal and transverse directions are taken.Then,based on these seismic actions,optimization of pier stiffness distribution in two directions is taken.The results show that the stiffness optimization can improve the seismic performance of the bridge.Subsequently,the multi-objective optimization analysis whose optimization parameter is the pier stiffness is carried out when all bears add some elastic restraint.The influence of the plastic parameters and the yield range of the pier on the key response of the bridge is analyzed.(3)Taking the continuous beam bridge with different dynamic characteristics as the analysis object,the influence of structural factors such as pier height and span on the optimization effect of the method introduced in this paper is analyzed.The research shows that the method has good optimization effect on the seismic performance of continuous beam bridges with different dynamic characteristics,and the optimization effect will change with the pier height and span.And these continuous beam bridges whose bears add an elastic restraint will further improve the seismic performance of continuous beam bridges.Finally,by changing the number of spans of the continuous girder bridge,taking the five span continuous girder bridge as an example,the effect of improving the seismic performance of the bridge by optimizing the distribution of pier stiffness is confirmed.