摘要:
冷弯薄壁型钢组合墙体在国内外多层钢结构住宅体系中已有较多应用。当用作双层墙体时,其上、下层墙段的连接处往往成为抗剪破坏薄弱部位。在考虑不同轴压力、不同墙体截面高度及不同锚栓等因素的前提下设计了9片墙体,对其进行低周往复加载的抗剪性能试验。结果表明:1)按JGJ/T 421—2018《冷弯薄壁型钢多层住宅技术规程》的要求设计的墙体,抗拔件螺钉承受拉剪作用,轴压的存在加速了螺钉的失效,导致承载力快速降低;2)墙体截面高度及轴压力对墙体承载性能影响很大,设计时应严格限制墙体轴压力;3)墙体经历了多个部件的渐次损伤,承载力及刚度退化较为缓慢,破坏是累积损伤的结果;4)双螺帽锚栓的墙体加载初期抗拔件上螺钉承受剪力作用,加载到大位移阶段,锚栓倾斜,螺钉改为承受拉剪作用,螺钉失效导致锚栓快速破坏,二阶效应使得下层墙体易发生层间破坏;5)在楼层连接处增设桁架加强部件后,抗拔件上螺钉仅承受剪力作用,使得墙体抗破坏能力明显提高,能明显改善墙体承载性能。
Abstract:
Cold-formed thin-walled steel composite wall has been widely used in steel multi-story dwellings at home and abroad. When it is taken as double-layer-load-bearing walls, the weak part is located in the floor connection between the upper and lower wall segments, which becomes the primary part of shear failure.Considering different the axial compression, wall cross-section height and anchor factors at a total of 9 pieces of wall were designed, to test their shear performance under quasi-static loading, the results showed that: 1) for the walls designed according to Technical Standards for Cold-Formed Thin-Walled Steel Multi-Storey Residential Buldings (JGJ/T 421—2018), pulling a screw under shear effect, the existence of axial compression accelerated the failure of screw resulted in the decrease of bearing capacity quickly; 2) the height of the wall section and the axial compression had a great impact on the bearing performance of the wall, so the axial compression of the wall should be strictly limited in the design; 3) the wall had experienced the gradual damage of multiple components, the bearing capacity and stiffness degradation were relatively slow, and the failure was the result of cumulative damage; 4) in the early stage of loading applied on the walls, the screws on the pull-out parts of the double-nut bolts bore shear force, and in the stage of large displacement, the inclined screws of the bolts bore tension-shear force. The failure of the screws led to the rapid destruction of the bolts, and the second-order effect made the lower wall prone to interlayer failure; 5) after adding truss strengthening parts at the floor joints, the screws on the pull-out parts only bore the shear force, so that the anti-damage ability of the wall was significantly improved, and the bearing capacity of the wall could be significantly improved.