| The multi-storey frame supported cold-formed thin-walled steel structure is a vertical irregular structure with flexible upper stories and rigid bottom.At present,there is a lack of experimental and theoretical research on the failure characteristics,dynamic response,and seismic performance of the structural system.Based on the experimental study of two-storey wall specimens,this paper extends the time history analysis method to the study of the seismic performance of the whole structure and puts forward the seismic design method combined with theoretical analysis.The main contents and conclusions of this paper are as follows:(1)Experimental study on shear behavior of frame supported cold-formed thinwalled steel two-storey wallUnder the action of horizontal low cycle reciprocating load,four full-scale steel frame supported cold-formed thin-walled two-storey wall specimens and two concrete frame supported cold-formed thin-walled two-storey wall specimens were tested,and their failure mechanism and interlayer connection were analyzed.The test results show that the hold-down and shear bolts can effectively connect the upper and lower structures and transfer the horizontal force;There was no obvious damage to the lower steel frame and concrete frame;The failure mode of the upper cold-formed thin-walled steel composite wall was mainly the failure of the connection between the wallboard and the cold-formed steel,resulting in the failure of the skin effect.(2)Finite element analysis of shear behavior of frame supported cold-formed thinwalled steel two-storey wallThe finite element model of frame supported cold-formed thin-walled steel two-storey wall was established by using ABAQUS software,and the nonlinear numerical simulation and parameter analysis were carried out.The results show that with the increase of vertical load,the elastic stiffness of the upper wall increases,and the yield load and peak load decrease;Reducing the outer spiral spacing can effectively improve the shear performance of the upper cold-formed thin-walled steel composite wall,while the inner spiral spacing has little effect;When the stiffness ratio is greater than 1,increasing the stiffness of the lower frame has little improvement on the overall shear performance.(3)Time history analysis of cold-formed thin-walled section steel supported by multi-storey frame under horizontal earthquakeThe overall finite element models of 18 cold-formed thin-walled steel sections supported by multi-storey frames were established.The displacement response,acceleration response and weak layer were studied by dynamic time history analysis.The failure mechanism of coldformed thin-walled section steel supported by multi-storey frame under horizontal earthquake was put forward,and the seismic design suggestions were given.(4)Seismic design method of cold-formed thin-walled steel structure supported by multi-storey frameAiming at the problem of irregular vertical stiffness of multi-storey frame supported coldformed thin-walled steel structure,the upper and lower division method was proposed.The seismic influence amplification factor β was proposed considering the influence of irregular stiffness on the superstructure under horizontal earthquake.Combined with theory and time history analysis,the β expression was proposed.The seismic performance level and performance target of multi-storey frame supported cold-formed thin-walled steel structure were determined,and the specific steps of seismic design method of multi-storey frame supported cold-formed thin-walled steel structure considering performance target were described.Using the seismic design method based on the upper and lower division method,a six storey frame supported cold-formed thin-walled steel structure was designed and analyzed.It was suggested that when the horizontal force is large,the multi-storey cold-formed thinwalled steel shear wall system should be selected for the superstructure. |
