曲率半径对曲线箱梁桥车辆荷载作用下冲击效应的影响

Influence of curvature radius on impact effects of a box-girder curved bridge under moving vehicle loads

针对复杂的车桥耦合振动问题,桥梁结构采用三梁式模型进行离散,首先基于ANSYS提出了简便的分离迭代解法,给出了该问题的详细推导过程和计算步骤,同时通过现场试验对所提出的方法进行了验证。通过快速傅里叶逆变换采用三角级数方法模拟了桥面不平度及其速度项,考虑车辆在曲线梁桥上的行驶偏心,分析了曲率半径和车速对曲线梁桥冲击效应的影响。结果表明:曲线梁桥的位移和内力动力放大系数大于直线梁桥的,且不同位置不同项目的内力和位移之间的动力放大系数的数值差别很大。内力和位移的动力放大系数对曲率半径的变化的敏感性各不相同,当曲率半径小于某个特征值后,动力放大系数变化很大。

Aiming at a complex coupled vehicle-bridge problem,a triple-beam model was applied to model bridge structure and a simple separation iteration solution method was presented based on ANSYS program.The detailed derivation process and computational procedures of the problem were also presented and validated by the field dynamic test of a preselected dual-box girder curved bridge.The inverse fast Fourier transformation was applied to generate road irregularity and its velocity term of grade B according to power spectral density of road roughness.The curvature radius and vehicle speed effects were analyzed based on the dynamic amplification factor(DAF) of a curved-bridge considering the traveling eccentricity of vehicles.The results indicated that the DAF of the curved bridge is larger than that of a straight bridge,and DAFs of internal forces and displacement at different positions are different significantly;the internal forces and displacements have different sensitivities to curvature radius,and their DAFs vary greatly while the curvature radius is smaller than a certain characteristic value.