桥梁相邻结构相对位移反应谱研究

基于相干函数和我国抗震设计规范定义的反应谱模拟了空间变化地震动,计算了桥梁相邻结构在不同视波速和相干程度空间地震动激励下的相对位移反应,以此确定为避免桥梁相邻结构碰撞所必需的伸缩缝最小间距,并分析了地震动空间变化和结构振动特性对桥梁相邻结构最大相对位移反应的影响。结果表明:地震动的空间变化对桥梁相邻结构的相对位移反应有着重要影响,当桥梁相邻结构拥有相似的振动频率时,影响最大;抗震设计标准推荐的调整相邻结构基本频率相近而减小相邻结构间的相对位移,从而达到避免结构碰撞的建议,仅在地震动空间变化效应可以忽略的前提下才有效。

Research on Relative Displacement Response Spectrum of Adjacent Bridge Segments

The spatially varying ground motions are simulated based on an empirical coherency loss function and the response spectrum defined in Chinese seismic design code.Calculations of the relative displacement response between two adjacent bridge segments to spatial ground motions with different wave velocities and coherency losses are conducted,which can be used to determine the minimum gap that an expansion joint must have to avoid pounding between bridge segments.Moreover,the influences on maximum relative displacement response between two adjacent bridge segments induced by ground motion spatial variation and structural vibration characteristics are investigated.Numerical results indicate that the effect of ground motion spatial variation on the relative displacement response is significant,especially when the vibration frequencies of two adjacent bridge segments are similar.To reduce the relative displacement and preclude pounding between adjacent structures,the design recommendation of adjusting the adjacent structures to have similar fundamental frequencies is valid only when the effect of ground motion spatial variation can be neglected.