短肢墙无粘结预应力楼盖结构顶层端节点抗震性能试验研究

本文通过两个由短肢墙、无粘结预应力现浇板和梁组成的空间组合体结构模型的低周反复加载试验,对采取两种不同构造方案共计4个顶层端节点的受力性能、传力机理以及进入节点区梁、墙肢钢筋的实测应变分布进行了分析研究。研究结果表明,短肢墙顶层端节点上部钢筋的粘结环境很差,梁端受弯屈服后,随着反复荷载作用,充分受力的负弯矩梁筋极易在节点顶部发生粘结退化甚至粘结失效,这种梁筋粘结明显退化和失效将对组合体的整体抗震性能带来较大的不利影响;短肢墙顶层端节点的传力机理不同于普遍框架柱节点,桁架机构是这类节点的主导传力机构;在试验研究的基础上,对短肢墙顶层端节点的构造措施提出了设计建议。

The earthquake resistant experimental research on knee joint of concrete structures with short flanged wall and unbonded prestressed slab

Cyclic tests on two sub-assemblages consisting of short-flanged walls, cast-in-place prestressed slab and beams were carried out. Behavior of 4 knee joints with two kinds of detailing schemes, their internal shear transfer mechanisms and measurements on strains of reinforcements in the joint core zone have been analyzed respectively. The analytical results showed that the bond of the upper reinforcement in the knee joint of the short-flanged wall is rather poor, and the bond deteriaration or failure may happen under negative cyclic moments. As a result, it is significantly unfavorable for the overall seismic behavior of the sub-assemblage. The shear transfer mechanisms of such kind of joint are different from that of the ordinary beam-column joint in which the truss mechanism is dorminant. On the basis of the test data, design proposals are suggested for this kind of joints.