大跨度悬索桥主引桥碰撞效应振动台试验及数值研究

摘要

In order to study pounding effect between main span and approach span of long-span multi-tower suspension bridges,a model for 1/40 scale of Taizhou Changjiang Highway Bridge was designed,constructed and tested on a shaking table.No connections were installed between the main beam and the middle tower in the longitudinal direction.Two fixed bearings and four polysaccharide rubber sliding bearings were installed between each approach beam and piers.The initial gap distance is 3 mm at the expansion joint.Pounding responses between the main span and the approach span were tested under three earthquake waves.The shaking table tests indicated that displacements of the approach and internnal forces acting on fixed piers of the approach span decrease due to the pounding effects between the main span and the approach one when the main span and the approach one are close to each other;however,displacements of the approach span and internal forces acting on fixed piers of the approach span increase due to thepounding effects when the approach span is chased by the main span.The numerical analysis results showed that the testresults can be simulated better when adopting Kelvin element combined with SAP2000 commercial software and the contactstiffness is taken as 0.2 times of the axial stiffness of the approach span.The selection of contact stiffness provided areference for similar bridges' pounding effect simulation.%为了研究大跨多塔连跨悬桥与引桥间的碰撞效应,以泰州长江公路大桥为背景,设计并制作1/40缩尺比例模型,进行了全桥振动台模型试验.主桥采用中塔与主梁间无连接的纵向约束结构体系,边跨梁每幅采用2个固定支座和4个聚四氟乙烯滑板支座,初始伸缩缝间隙为3 mm,试验分别测试了3条地震波下主引桥间的碰撞响应.振动台试验表明,主桥与引桥相互靠近运动时,主引桥间的碰撞会减小引桥梁位移及固定墩内力的需求;当主桥追逐引桥运动时,主引桥间的碰撞会增大引桥梁位移及内力的需求.数值模拟结果表明:采用SAP2000商业软件组合Kelvin单元,接触刚度取引桥梁轴向刚度的0.2倍时,能较好的模拟试验结果;接触刚度取值可为相似桥梁碰撞效应模拟提供试验参考.