后张预应力混凝土摇摆墙非线性分析

Nonlinear analysis of post-tensioned prestressed concrete rocking walls

摘要:

为分析后张预应力摇摆墙通过摇摆界面处墙趾的张合行为降低结构损伤和震后残余变形的特性,须解决墙趾节点约束释放后的局部行为、沿墙通长布置的后张无黏结预应力应力变化与摇摆机制关系等关键问题。结合非线性宏单元的思路,用多个轴压弹簧模拟墙体与基础界面水平接缝开合行为及接缝区域力学特性,用共转桁架单元模拟预应力筋受力特征,提出了基于OpenSees的循环往复加载摇摆墙多弹簧模型,模拟的滞回特性、骨架曲线、耗能能力与试验结果吻合较好,3个试件水平承载力计算值及极限变形计算值与试验结果之比分别为1.042、0.996、1.061和0.993、0.998、0.995。 实现了反映墙趾开合性能的受压区高度的高精度预测,并较好地模拟了反映其自复位性能的残余变形及预应力筋应力变化。 分析结果显示:3个后张预应力混凝土摇摆墙试件在峰值侧移下残余侧移比分别仅为0.060%、0.121%、0.124%,且结构损伤小；应在保证结构变形能力和恢复能力的同时,提升其耗能能力。

Abstract:

To analyze the characteristics of post-tensioned prestressed rocking walls in reducing the structural damage of the wall and the residual deformation after earthquakes through the opening and closing behaviors of the wall toe at the rocking interface, it is necessary to solve the key issues such as the local behavior of the wall toe nodes after the restraint is released, and the relationship between the stress change in the post-tensioned unbonded prestressed tendon and the rocking mechanism arranged along the entire length of the wall. Based on the idea of nonlinear macro-element, multiple axial compression springs were adopted to simulate the opening and closing behavior of the horizontal joint between the wall and the foundation interface as well as the mechanical characteristics of the joint area, and the co-rotating truss element was applied to simulate the force characteristics of the prestressed tendons. The multi-springs model of rocking wall under cyclic reciprocating loading was proposed based on OpenSees, and the simulated hysteresis characteristics, skeleton curve, and energy dissipation capacity were in good agreement with test results. The ratios of the calculated values of horizontal bearing capacity and ultimate deformation of three specimens to the test results were 1.2,0.6,1.061 and 0.3,0.8,0.995, respectively. The model could realize the high-precision prediction of the height of the compression zone reflecting the gap opening and closing of the wall toe, and could simulate the residual deformation and the stress change in the prestressed tendon reflecting its self-centering capacity. The analysis results show that residual lateral displacement ratios of the three post-tensioned prestressed concrete rocking wall specimens under the peak lateral displacement were only 0.060%, 0.121%, and 0.124%, respectively, and the structural damage was small. The energy dissipation capacity should be improved while ensuring the structural deformation and recovery capacity.