行波激励下大跨度桥梁考虑SSI效应的地震响应分析

SSI Effect on Seismic Response of A Long-span Bridge under Traveling Wave Excitation

为了研究行波效应和SSI效应对大跨度钢筋混凝土刚构—连续梁组合桥非线性地震响应的影响规律,选取ElCentro地震波、唐山地震北京波,分析了某六跨钢筋混凝土刚构—连续梁组合桥在一致激励和行波激励下的非线性地震响应,研究了行波效应和SSI效应对该刚构—连续梁组合桥地震响应的影响规律。结果表明,行波效应增大了箱梁的受力,箱梁应力峰值随视波速增大单调递减;行波效应使墩梁固结桥墩的受力和变形呈非单调变化规律,地震响应峰值随视波速增大而先减小后增加;SSI效应增大了桥梁结构地震响应,其峰值随剪切波速增大单调递减;同时考虑行波效应和SSI效应,地震响应峰值随视波速变化曲线的拐点位置和切线斜率均发生改变,其地震响应幅值不是两种效应影响下的简单叠加;行波效应和SSI效应对桥梁地震响应的影响程度随地震波和墩梁约束条件的不同而有所差异。

Nonlinear seismic response analysis of rigid-frame continuous girder combination bridges is conducted considering traveling wave effect and soil-structure interaction. The results show that the seismic responses of the box-section girders increases due to traveling wave effects. However,the dynamic responses of bridge piers perform a non-monotonic variation. The seismic responses of bridge also increase due to SSI. The peak of the responses monotonously decreases as the shear wave velocity increases. When the two factors are simultaneously considered,the inflection points and the tangent slopes of peak amplitude-apparent velocity curves are both changed. The corresponding responses cannot be evaluated by simply superposition on the individual responses due to either traveling wave effects or SSI. The influence magnitudes of traveling wave effects or SSI are different in terms of earthquake waves and the constraints between the beams and bridge piers.