基于虚拟激励法的大跨径斜拉桥随机地震效应主塔力学响应特征

Mechanical Response Ccharacteristics of Main Tower with Random Seismic Eeffect on Long-span Cable-stayed Bridge Based on Virtual Incentive Method

为探究斜拉桥主塔在随机地震下的空间效应力学行为,以某大跨径斜拉桥为研究对象,基于虚拟激励法,分别对行波效应、相干效应及局部场地效应下主塔受力规律进行对比分析。研究表明:行波效应下主塔根部弯矩有一定程度降低,但控制截面剪力和轴力有所增大,且行波效应受视波速影响明显;基于QWW相干模型时,主塔根部弯矩、剪力及顺桥向位移均呈减小趋势;局部场地效应将大幅增大主塔内力响应值,且影响效应主要受覆盖土厚度差的影响。

A long-span cable-stayed bridge is taken as the research object to explore the spatial effect mechanical behavior of the main tower of the bridge under random earthquakes.based on the virtual excitation method,the force law of the main tower under traveling wave effect,coherent effect and local site effect is compared and analyzed.The research shows that under the traveling wave effect,the bending moment of the root of the main tower is reduced to a certain extent,but the shear force and axial force of the control section are increased,and the traveling wave effect is significantly affected by the apparent wave velocity;when based on the QWW coherent model,the bending moment of the main tower root,Shear force and displacement along the bridge direction are decreasing;local site effect will greatly increase the response value of the internal force of the main tower,and it is mainly affected by the difference in the thickness of the cover soil.