简支梁桥顺桥向地震动分析

为了计算多跨简支梁桥地震荷载,根据弹性地基上桥墩的变形特性,将墩顶作用单位集中力时,桥墩静力挠度曲线方程作为基本振型,考虑了地基变形的影响,利用拉格朗日方程推导了多跨简支梁桥顺桥向地震振动方程,给出了相应的基频和振型参与系数的近似计算公式。仿真计算结果表明:简支梁桥一、二阶自振频率的计算值分别为7.43及11.19 Hz,而其试验值分别为7.00及10.55Hz,其误差在5.8%以内。可见,提出的振型可以用于简支梁桥顺桥向的抗震性能评估。

Analysis of longitudinal seismic vibration for simply-supported beam bridge

In order to compute the seismic loads of multi-span simply-supported beam bridge,according to the deformation behavior of piers sited on elastic foundations,pier's deflection function was taken as the fundamental vibration mode,it was derived under unit force acting on pier's top,the effect of foundation deformation was taken into account,the longitudinal seismic vibration equation of the bridge was deduced by Lagrange function,and the approximate formulas of its fundamental frequency and participation factors were put forward.Simulated result shows that the first and second calculated vibration frequencies are 7.43 and 11.19 Hz respectively,and their corresponding test values are 7.00 and 10.55 Hz respectively,their errors aren't more than 5.8%,which demonstrates that the mode is appropriate for assessing the longitudinal seismic performance of the bridge.1 tab,4 figs,11 refs.