SHEAR PERFORMANCE EXPERIMENTS OF COLD-FORMED THIN-WALLED STEEL LOAD-BEARING WALLS

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.