基于直杆共轴碰撞理论的桥梁地震反应邻梁碰撞分析模型

桥梁结构在强烈地震动作用下,伸缩缝两边的主梁会因运动的相对位移大于伸缩缝间距而发生碰撞,造成桥梁结构损坏,甚至引发落梁。研究目的是建立较合理的邻梁碰撞问题分析模型。通过引入表征邻梁碰撞相互作用的碰撞弹簧,基于直杆共轴碰撞理论建立了邻梁碰撞问题的分析模型,采用解析与数值结合的方法研究了碰撞弹簧刚度比a、邻梁长度比12/ll和阻尼比x等参数对碰撞力、碰撞持续时间和耗能的影响。利用美国加州强震观测计划(CSMIP)获得的邻梁碰撞强震记录,估计了碰撞弹簧刚度约为0.5倍的较短主梁轴向刚度。

ANALYSIS MODEL OF POUNDING BETWEEN ADJACENT BRIDGE GIRDERS DURING EARTHQUAKES BASED ON COLLINEAR IMPACT BETWEEN RODS

Pounding will occur between adjacent bridge girders if the maximum relative displacement is larger than the expansion joint gap during earthquakes. Pounding may result in structural damage or even lead to collapse of superstructures. The study is aimed at establishing a reasonable analysis model of pounding between adjacent bridge girders during earthquakes. Bridge girders are modeled as elastic rods with the same cross section and collinear impact between them is expressed by a impact spring. Effects of parameters including impact spring stiffness ratio a, length ratio 12/ll between adjacent bridge girders and damping ratio ξ on impact force, impact duration and energy loss are discussed on the basis of analytical solution and numerical simulation. In determining a suitable value of impact spring stiffness, the strong-motion data recorded on a concrete bridge instrumented by the California Strong Motion Instrumentation Program (CSMIP) are used. The impact spring stiffness is found to be about 0.5 times that of axial stiffness of the shorter bridge girder.