预应力自复位钢筋混凝土柱及梁柱节点拟静力试验研究

Pseudo-static tests of prestressed self-centering reinforced concrete column and beam-column joints

装配式预应力自复位钢筋混凝土结构在地震后构件无损伤或损伤很小,可尽快恢复使用功能,大大降低震后经济损失,从而得到研究者的广泛关注。在以往的装配式预应力自复位钢筋混凝土结构中,节点上的外置阻尼器多选用小型防屈曲支撑,费用较高。本文提出在柱-基础节点及梁柱节点中,用价格低廉且同样具有较好耗能能力的普通角钢替代作为阻尼器,开展了拟静力试验。以往同类型构件试验仅关注试件在单向荷载作用下的性能,本试验同时研究了构件在阻尼器工作的垂直方向上构件的力学性能。文中共进行了两组试验,一组针对自复位柱-基础节点,研究构件加载方向、轴压比、极限位移等因素对构件性能的影响;另一组针对自复位梁-柱节点,研究柱轴压比、极限位移对构件性能的影响。试验结果表明:加载到最大层间位移角为1/15时,试件无明显破坏,预应力钢绞线保持在弹性阶段,始终能够提供恢复力;外置角钢产生弹塑性变形耗散能量,试件耗能能力较好。卸载后,残余变形很小,可以在震后方便地更换外置角钢。

There is no damage or slight damage for the assembled prestressed self-centering reinforced concrete structure after earthquakes. So the structure can be used as soon as possible and economic losses are greatly reduced. This kind of structure was widely concerned by researchers. Small buckling restrained braces （BRB） were often chosen as dampers at the nodes of these structures. The costs are relatively high. In this study, common used angle steel was used as dampers at the nodes of the structure to replace the small BRBs, which has much lower costs but alike energy dissipation ability. Experiments for the components with such nodal dampers were carried out. Different with previous similar tests, the behavior of the components at the direction that is perpendicular with the working direction of the dampers were also tested. The tests for two kinds of specimens were performed. One was node connecting self-centering column and foundation, the other was node connecting column and beam. The influence of factors including loading direction, axial compression ratio and ultimate displacement on behavior of the first kind of specimen was addressed. For the second kind of specimen, only the influence of axial compression ratio and ultimate displacement was tested. The experimental results show that until the story drift reaches 1/15, the prestressed tendons remain elastic and provide the resilience all the time, the components have good self-centering ability. The connections dissipated the energy by the elastic-plastic deformations of the angles, and they have good ability of energy dissipation. After unloading, the residual deformations of the connections are small, which shows that the angle steel can be replaced easily after the earthquake.