大跨三塔悬索桥伸缩缝处纵向碰撞对结构地震反应的影响

Effect of Pounding at Expansion Joints of Long-span Triple-pylon Suspension Bridge on Seismic Response of the Structure

针对大跨桥梁在地震作用下伸缩缝处的碰撞现象,以一座大跨3塔悬索桥为例,建立了考虑塔、墩弹塑性的空间非线性碰撞模型,采用非线性时程法研究了地震作用下伸缩缝处碰撞对结构地震响应的影响。分析结果表明:当引桥振动基本周期大于主桥位移控制振型周期时,碰撞可能使引桥墩底、主引桥相对位移及引桥梁体搭接长度响应地震增大,且随着主桥和引桥位移控制振型周期差异逐渐增大,碰撞效应总体上对主桥的地震响应影响较小。

Based on the pounding phenomenon at expansion joints of long-span bridge under earthquake and in combination with a realistic engineering project of a long-span triple-pylon suspension bridge, the complex 3D nonlinear pounding model that considered elastoplastic character of pylon and piers was developed. The pounding effects on seismic responses of the main span and the approach span were studied by using nonlinear time history method： The results indicate that （ 1 ） as the vibration period of the approach span is longer than the control vibration period of displacement of the main span, the pounding could amplify the seismic responses of relative displacement between bottoms of piers of the approach span and main span as well as the hinge seat width of beam of approach span, and the effects increased gradually with the difference of control vibration period of relative displacement between main span and approach span increases; （2） the pounding has light effect on seismic responses of the main span.