地震时桥梁碰撞分析的等效Kelvin撞击模型

建立地震时桥梁碰撞分析的Kelvin撞击模型的参数确定方法。基于Hertz接触理论,考虑波动效应,按照最大撞击力与最大撞击变形的比值,确定Kelvin撞击模型的碰撞刚度;数值分析了影响Kelvin撞击模型阻尼系数取值的邻梁碰撞恢复系数。结果表明:Kelvin撞击模型的碰撞刚度随Hertz接触刚度、撞击速度以及短梁与长梁的长度比的增大而增大;波动效应对碰撞刚度的影响明显,不能忽略;邻梁碰撞恢复系数随撞击速度增大而减小,随短梁与长梁的长度比减小而减小;确定Kelvin撞击模型的碰撞刚度和邻梁碰撞恢复系数对城市桥梁的合理取值范围应分别为3×105kN/m―6×105kN/m和0.7―0.95。

EQUIVALENT KELVIN IMPACT MODEL FOR POUNDING ANALYSIS OF BRIDGES DURING EARTHQUAKE

A method to determine the parameters of Kelvin impact model for pounding analysis of bridges during earthquake is proposed. Based on Hertz contact theory and considering the wave effect, the impact stiffness of Kelvin impact model is determined according to the ratio of maximum impact load to maximum contact deformation. The recovery coefficient of pounding between adjacent girders, which influences the sampling of the damping coefficient of Kelvin impact model, is numerically analyzed. The results indicate that the impact stiffness of Kelvin impact model increases with an increase in the Hertz contact stiffness, the impact velocity, and the length ratio of the short to long girders. The wave effect has remarkable influence on the impact stiffness and can not be neglected. The recovery coefficient of pounding between adjacent girders decreases with an increase in the impact velocity, but with a decrease in the length ratio of the short to long girders. The rational sampling ranges of the impact stiffness of Kelvin impact model and the recovery coefficient of pounding between adjacent girders for urban bridges are found to be 3×105 kN/m―6×105 kN/m and 0.6―0.95, respectively.