地震作用下多跨简支梁桥挡块优化设计研究

Study on optimum design of transverse retainer of multi-span simply supported bridges considering the earthquake

为研究墩柱损伤时弹塑性挡块的合理参数设计,以三跨简支梁桥为例,建立了OpenSees有限元软件计算模型。通过非线性时程分析,动态调整挡块屈服强度,建立了挡块屈服与墩柱损伤状态之间的直观联系,分析了弹塑性挡块初始刚度、屈服后刚度比参数。研究结果表明:挡块强度的增大,其限位能力也增强;当桥墩挡块强度的设定以桥墩达到中等损伤为目标时,有利于地震惯性力合理分配;挡块初始刚度的增大,可有效降低主梁位移响应,其对桥墩地震响应的影响较挡块强度的小;强震作用下挡块屈服后,桥梁地震响应对挡块屈服后刚度的变化十分敏感,较小的屈服后刚度比对下部结构抗震有利,同时不会造成上部结构位移需求的急剧增长。

In order to study the reasonable parameter of the elastic-plastic retainer considering the damage of the pier column,a three-span simply supported girder bridge model was established using the finite element software of OpenSees.The yield strength of retainer was dynamically adjusted through nonlinear time history analysis.An intuitive connection was established between the yield strength of the retainer and the damage state of the pier column.The initial stiffness of the elastoplastic retainer and the stiffness ratio after yielding were analyzed.The results show that,the action of retainer can be improved by increasing the strength.When the strength of the retainer is set to achieve the moderate damage stress of the pier,it is conducive to reasonably distribute the seismic inertial force.The displacement response of main beam can be reduced effectively by increasing the initial stiffness of the retainer.The influence of initial stiffness on the seismic response of the pier is smaller than that of the strength.When the yield of retainer is induced by the strong earthquake,the seismic response of the bridge is very sensitive to the change of the stiffness.A small post-buckling stiffness ratio is beneficial to the seismic resistance of the substructure,and the sharp increase displacement demand of the upper structure can be limited.