纵向地震作用下大跨三塔悬索桥伸缩缝处双边碰撞效应研究

相邻桥跨间的碰撞效应是引起大跨桥梁引桥落梁的重要原因，本文以一座大跨三塔悬索桥为研究对象，建立了复杂的桥梁结构空间动力分析模型，采用非线性动力时程分析法，详细分析了大跨三塔悬索桥伸缩缝处主、引桥相邻梁体间的双边碰撞对桥梁结构地震反应的影响规律，揭示大跨桥梁主、引桥结构振动周期比与碰撞效应的内在联系。研究结果表明：当一侧引桥基本周期小于或者接近主桥梁端位移控制振型周期，而另一侧引桥基本周期显著大于主桥周期时，双边碰撞使长周期侧的引桥固定墩墩底地震内力响应、梁端位移、梁体搭接长度以及主、引桥间相对位移响应显著增大，而使短周期侧引桥梁端位移、梁体搭接长度以及主、引桥间相对位移响应轻微减小。

Effect of double-side pounding at expansion joints on seismic response of Long-span Triple-pylon Suspension Bridge

The pounding effects at expansion joints is one of the important reasons of approach span girders falling off their support of long-span bridge under earthquake. In this paper, one long-span triple-pylon suspension bridge as the research object, the complex space dynamic analysis model was developed. Using the nonlinear time history analysis method, the double-side pounding effects of adjacent girders at expansion joints on seismic responses of the bridge were studied. And the internal relations between the pounding effects and vibration period of the main span and the approach span. The results indicate that as the period of one side approach span is shorter than or close to the main span’s and the other side’s is longer than the main span’s obviously, the double-side pounding can amplify the seismic response of the longer-period side approach span, such as seismic response of the piers, the displacement of main girder, the hinge seat width of beam of approach span and the relative displacement between main span and approach span. Contrarily, the double-side pounding decreases slightly the corresponding seismic response of the shorter-period side approach span.