Study On Seismic Behavior Cold-formed Thin-walled Steel Walls With Diagonal Braces

In this paper,the seismic behavior of a cold-formed thin-walled steel wall with diagonal braces is studied by means of experimental study,finite element analysis and theoretical derivation.And the formulas for calculating the bearing capacity of walls are proposed.The seismic performance of walls can be effectively improved by setting rigid braces.The specific research contents are as follows:(1)Horizontal hysteretic loading tests on 7 full-scale cold-formed thin-walled steel walls were carried out.The effects of diagonal bracing,opening,screw spacing,single-sided and double-sided cladding and vertical load on the seismic performance of walls were investigated.The failure modes of the specimens are summarized and the load-displacement curves were obtained.The effects of various parameters on the seismic performance indexes such as bearing capacity,ductility,stiffness degradation,strength degradation and energy dissipation capacity of walls were also analyzed.The walls were mainly suffered from screw connection failure around the wall panel and buckling failure at the joint between cross brace and diagonal brace.The shear capacity of the wall with diagonal braces is obviously higher than that without diagonal braces.(2)The finite element model of wall specimen is established by ABAQUS software.Both cold-formed thin-walled steel and OSB panel were simulated by shell element.A series connector model was proposed to simulate self-tapping screw connection.The model can well realize the "pinch-slip" characteristics of self-tapping screw connections under hysteretic loads.It was set up in the whole model to simulate the wall under hysteretic loading.Compared with finite element calculation and test,the failure simulation,hysteresis curve and bearing capacity were in good agreement.The correctness of the finite element model was verified.(3)Based on the finite element model of wall verified by experiment,the parameters of the cold-formed thin-walled steel wall were analyzed.The effects of panel splicing,wall height-width ratio,screw spacing around the panel,cross bracing parameters and bracing arrangement on the shear capacity of the wall were studied.The key parameters affecting the bearing capacity of the wall were determined.The splicing method of wall panels and the ratio of height to width of walls have little influence on the shear capacity of walls per unit length.(4)Based on the test and a lot of parameter analysis results,a formula for calculating the shear capacity of cold-formed thin-walled steel walls with diagonal braces was proposed through theoretical analysis.The formula calculation is in good agreement with the results of finite element analysis.