大尺度新型卷边PEC柱-钢梁T形件摩擦耗能型连接中节点抗震试验研究

Test study on seismic performance of large-size interior joint between innovative PEC column-steel beam with frictional energy-dissipation t-stub connection

本文考虑柱轴压力、PEC柱布置方式和钢板组合截面类型等设计参数,对4个大尺度新型PEC柱-钢梁T形件摩擦耗能型中节点试件进行拟静力试验。基于试验数据,分析了试件承载能力、连接力学性能、节点传力机理和破坏模态等抗震性能。研究结果发现:新型卷边PEC柱较大程度增强了核心区混凝土的约束作用,更好满足"强柱弱梁"的抗震设计要求;PEC柱轴压力增大了节点初始转动刚度,其二阶效应降低了节点抗弯承载力,但加快了梁截面进入屈服的损伤进程;预拉对穿螺栓使节点域实现了混凝土斜压带传力机理,相应降低了节点区的抗剪需求,且具有一定的自复位功效;由于T形件对节点的加强作用,使得除试件SLJ3外的其余试件破坏模态均为T形件端部外排螺栓附近钢梁截面充分屈服形成塑性铰的理想延性破坏机构,对应连接转角均大于大震层间相对侧移限值1/30,表明摩擦耗能型连接较好实现了"小震通过摩擦耗散地震能,中大震利用T形件端部外排螺栓附近梁截面屈服耗散地震能"的设计目标。

Primary design parameters as axial compression,column layout and thin-walled built-up section were taken into consideration,4 large-size interior joints of innovative PEC column-steel beam with frictional energy-dissipation T-stub connection were fabricated and investigated by pseudo-static tests. Based on the test data and observation,the specimens global behaviors were studied,including the load-carrying capacity,the mechanical performance of connection,force-transferring mechanism of the panel zone and the failure mode. The results showed that the crimping of flange can well confine the concrete to achieve the seismic design principle of ＂strong column weak beam＂; axial compression increase its initial flexural stiffness but lower the load-carrying capacity and accelerate the yield process of beam section due to its second-order effect; the force-transfer mechanism of concrete equivalentstrut in the panel zone alleviates its shear demand attribute to through-out bolts,and all specimens exhibited various degrees of self-centering functions; the failure mode formed primary induced by yielding in the cross-section of beam nearby the end of T-stub and the connection rotation surpassed the limit（ 1 /30） of maximum considered earthquake for structure,correspondingly the connection achieves the design target as energy is dissipated by friction at frequently occurring earthquake level and by yielding of beam at design basis earthquake level or maximum considered earthquake level.