纵向地震作用下系杆拱桥与引桥间碰撞响应研究

Analysis of Pounding Effect of Longitudinal Ground Motion on Tie Arch Bridge and Side Span

地震作用下，作为主跨的系杆拱桥与连接跨处容易发生碰撞和落梁现象，本文以双自由度简化分析模型为研究对象，考虑梁间伸缩缝处的碰撞。分析结果表明：周期比是影响碰撞力的主要因素，碰撞对伸缩缝两侧结构地震反应的影响与结构周期相关，周期相近的主跨和边跨碰撞力较小，周期比在0．3～0．4时，峰值碰撞力最大，碰撞可以减低柔性墩柱剪力，减小主跨和边跨之间的相对位移，碰撞力一般随伸缩缝间隙增加而减小。

Pounding and deck unseating may occur at the main span and the side span of the tied arch bridge during the ground motion. A simplified tied arch bridge model with two degrees of freedom is employed. Results show that the period ratio is the essential parameters to influence the pounding effect, and the pounding effect is relative to the natural period of the bridge. The pounding force is lower when the interval of the natural periods of two sides decreases. When the period ratio is about 0. 3 - 0. 4, the force of peak pounding becomes maximal. The relative displacement can reduce the pounding effect, and the pounding force will be generally reduced with the increasing of the interval of the expansions joint.