预应力摇摆双层桥梁框架墩结构体系地震反应分析

Seismic response of post-tensioned double-deck rocking frame bridge pier system

为了提升双层桥梁结构震后功能的可恢复性,本文提出一种预应力摇摆双层桥梁框架墩结构体系。采用拉格朗日方程和动量矩守恒定理建立该类摇摆双层桥梁框架墩的动力反应分析模型,进行了结构地震反应的分析,给出了预应力束参数对体系地震反应的影响,并对Ricker小波作用下结构的抗倒塌能力进行了分析。研究结果表明:采用实际工程尺寸的预应力摇摆双层桥梁框架墩在E2地震作用下的残余位移小,结构基本无塑性损伤;增大初始预应力参数ρ_(t0)可以减小上层墩柱的位移反应,但下层墩柱的反应呈现一定程度的增大;在一定频率范围内预应力设计参数的增大可以提升结构的抗倒塌能力,但在另外一些频率范围内则存在负效果。

To improve seismic resilience of double-deck viaducts,a post-tensioned double-deck rocking frame bridge pier system is developed.Based on Lagrange equation and conservation of angular momentum,a dynamic analytical model of the rocking bridge is derived.Seismic response of the rocking system is analyzed and the influence of the parameters of post-tensioned tendons on rocking system is given using the analytical model.The overturing resistance of the rocking bridge under Ricker wavelet is evaluated.The results show that rocking frame pier with dimension in practice exhibits minor damage and residual displacements.With the increase of the initial prestress of the tendon,drifts of the upper columns decrease,whereas drifts of the lower columns show an increasing trend.In certain frequency range,the increase of the tendon design parameters can improve the overturing resistance of the rocking pier,while for other frequency range the tendon parameters jeopardize the stability of the system.