自复位装配式钢-混凝土混合框架节点抗震性能试验研究

结合装配式梁、柱构件螺栓连接施工便捷的特性与后张预应力筋预压连接的抗震性能优势，提出一种自复位装配式钢-混凝土混合结构框架节点，该节点由钢筋混凝土柱和钢-混凝土混合梁通过高强螺栓拼装而成，主要通过后张梁内的无黏结预应力筋提供复位力，并通过摩擦耗能装置与钢梁段塑性变形进行耗能。共完成了5个边节点的低周往复加载试验，分别研究了混合梁内预应力筋的初始预拉力与摩擦装置中高强螺栓的初始预紧力对该节点承载能力、抗震性能、耗能能力和复位能力的影响。研究结果表明：试件表现出明显的两阶段滞回特性，第一阶段为钢梁段屈服前，混凝土梁与钢梁段接触面呈现出持续开合复位机制，滞回曲线呈现明显双旗形，复位效果明显；第二阶段为钢梁段屈服后，随着荷载增大，钢梁的塑性变形逐渐增大，滞回曲线趋于饱满，试件耗能能力显著增加。试件的峰值荷载、延性系数和累积耗能值随摩擦装置中高强螺栓的初始扭矩增大而增大，峰值荷载和复位能力随梁内预应力筋的初始预拉力增大而增大。在整个试验过程中，各试件梁、柱主体构件损伤不明显，基本实现震后可恢复。

Experimental study on seismic behavior of self-centering fabricated steel-concrete hybrid exterior joint

In order to combine the advantages of convenient construction of the bolted connection and seismic performance of the post-tensioned connection in prefabricated concrete structures, a self-centering fabricated steel-concrete hybrid exterior joint was proposed. The joint was assembled by a reinforced concrete column and a steel-concrete hybrid beam with high-strength bolts. The resilient ability was mainly provided by unbonded post-tensioned strands in the beam, and the friction device and plastic deformation of the steel beam section provided the energy dissipation capacity. Pseudo-static tests were conducted on five exterior joint specimens to analyze the bearing capacity，seismic behavior，energy dissipation capacity and self-centering capacity. The effects of initial pre-stress of the strands and the initial pretension force of the high-strength bolts at the friction device were critically investigated. The test results indicate that hysteresis curves of specimens can be divided into two typical stages. In the first stage before the yielding of the flanges of steel beam section, the contact interface between the concrete beam and the steel beam section shows a continuous opening and closing mechanism. The hysteresis curves exhibit a clear double flag shape, and the residual deformation is small. In the second stage after the yielding of steel flanges, the plastic deformation of the steel beam section increases with the increase of the lateral load. The hysteresis curve becomes plumper, and the energy dissipation capacity of specimens increases significantly. The peak load, ductility coefficients and cumulative energy dissipation increase with the increase of the initial torque of the high-strength bolt at the friction device. The peak load and self-centering ability increase with the increase of the initial pretension force of applied strands. During the entire test process, the damage occurring in the primary members is not obvious, and the resilience after the earthquake is basically achieved.