基于核密度估计法的大跨度非对称悬索桥碰撞概率分析

Pounding probability analysis of a long-span asymmetric suspension bridgebased on a kernel density estimation method

为了对随机地震作用下大跨度非对称悬索桥的梁端碰撞概率进行评估,基于OpenSEES建立了一座典型实例桥的三维非线性有限元模型,综合考虑了地震动与模型参数的双重随机特性,采用拉丁超立方抽样与核密度估计方法建立了桥梁碰撞概率模型,并验证了该方法的有效性,最后分析了桥梁结构随机参数、伸缩缝宽度及非线性阻尼器对悬索桥梁端碰撞概率的影响。分析结果表明:若忽略桥梁结构参数的不确定性可能会高估桥梁的碰撞概率,其最大误差可达122%;大震作用下非线性阻尼器可以显著减小桥梁的碰撞概率,且阻尼器的减震效果随着伸缩缝宽度增大而越加明显;当PGA<0.7g时,通过设置阻尼器不仅可以减小悬索桥的碰撞力峰值,而且可以减少梁端碰撞次数;当PGA>0.7g时,阻尼器对碰撞次数影响较小,但能明显降低其碰撞力。

To evaluate the beam-end pounding probability of a long-span asymmetric suspension bridge subjected to random earthquake action,a three-dimensional nonlinear finite element model of a typical example bridge was established using the OpenSEES software.The bridge pounding probability model was proposed based on the Latin hypercube sampling and the kernel density estimation method by considering the random characteristics of both ground motion and model parameters,and its validity was verified.Finally,the influences of random parameters of bridge structure,expansion joint width,and nonlinear damper on the beam-end pounding probability of the suspension bridge were investigated.Results indicate that the bridge pounding probability may be overestimated with the maximum error of 122%if the uncertainty of bridge structural parameters is ignored.The pounding probability of the bridge under severe earthquakes can be decreased significantly by using the nonlinear damper,and the seismic mitigation effect of the damper increases with expansion joint width.When the PGA is less than 0.7 g,the damper can both reduce the peak impact force of the suspension bridge and the pounding times of the beam-end.When the PGA is greater than 0.7 g,the damper has little effect on the pounding times while can evidently reduce the impact force.