Seismic Performance Of The Cold-formed Thin-walled Steel Composite Wall With Diagonal Bracing And Vertical Load

In recent years,China has vigorously promoted the "green assembly-type building",and the cold-formed thin-walled steel-structured residential system has been rapidly promoted as a representative of assembly buildings.The composite wall made of panel material and steel keel is the main load-bearing structure of the cold-formed thin-walled steel structure residential system,although a number of experimental studies and finite element simulation analysis have been conducted on the seismic performance of cold-formed steel composite walls at home and abroad,its structural forms include: open-hole wall,X cross-belt support wall composite wall,steel-clad wall,etc.,but so far,for the cold-formed thin-walled steel composite wall with diagonal rigid support The study of the mechanical properties is still rare.Especially the seismic performance of such walls considering vertical loads,there is still a lack of systematic research.In this paper,through the experimental research and theoretical analysis of the diagonally braced cold-formed thin-walled steel composite wall subjected to vertical loads,the mechanical properties,failure modes and hysteresis properties of the wall were investigated;and the influence of the vertical load(axial ratio of wall frame column)and the yield strength of the steel keel on the seismic performance of the wall were discussed;and based on the results of the test and the finite element analysis,the design methods and recommendations of the wall under seismic loads were proposed.(1)A horizontal low-cycle loading test was performed on a total of six walls under a vertical load with a diagonal bracing cold-formed thin-walled steel composite wall without panel and a single-sided OSB panel.The stress properties and failure modes were investigated;the mechanical properties such as hysteretic properties,ductility,and energy dissipation were analyzed.The experimental study shows that: under the same vertical load,the shear bearing capacity of the single-sided OSB panel is increased by 38.79% compared with the non-paneled wall,indicating that the panel has a strong restraining effect on the wall,.the contribution to the increase of bearing capacity in the wall with diagonal support is still significant;the shear bearing capacity of the the single-sided OSB panel composite wall with axial compression ratio of 0.24 is increased by 7.5% than the axial compression ratio of 0.16,but the yield displacement is reduced.8.1%,indicating that the larger axial compression ratio produced by the larger vertical load increases the lateral stiffness of the wall,the wall ductility coefficient ? increases by 4.5%,and the energy dissipation factor E increases by 4.1%,indicating that the energy consumption of the wall has increased under larger axial compression ratio.(2)For the same batch of component materials and screws used in this test,the connection performance of self-tapping screws was tested.The results show that: the data of screw shear test have a certain degree of dispersion.The shear bearing capacity and deformability of connectors increase with the increase of the thickness and number of steel plates.The maximum shear load of three steel plates overlaps is about two times as two steel plates;12mm thick OSB,the maximum shear strength of the fiber parallel to the direction of the plate length and perpendicular to the plate length difference is not obvious,because the strength of the OSB plate is far lower than steel,the shear bearing capacity of the steel-OSB plate connector is significantly lower than the two steel plate connectors.(3)The finite element parameters simulation analysis was performed on the shear resistance of the combined wall under the low-cycle load.First of all,based on the test results,the rationality and effectiveness of the finite element model are verified.On this basis,the influence of factors such as wall column axial compression ratio and yield strength of steel keel on the mechanical properties of the wall was investigated by variable parameter analysis.The analysis results show that: with the increase of axial compression ratio,the shear bearing capacity of the wall has improved;Reducing the yield strength of the steel keel significantly reduces the shear capacity of the composite wall.(4)On the basis of experimental research and finite element analysis,based on the design regulations and theoretical background of the Technical Specification for Low-rise Cold-formed Thin-walled Steel Framing Buildings(JGJ227-2011)and the United States Standard AISI S400-15,derivation The “resistance partial coefficient” of the wall,determines the design value of the shear bearing capacity under horizontal earthquake,and provides a reference for guiding the structural design of the wall.