Seismic Performance Analysis Of The New-Type Cold-Formed Thin-Walled Steel Residential Buildings

Cold-formed steel composite wall is the major member of the cold-formed thin-wall steel residential building.The composite wall bears the vertical load and the horizontal load,in which the vertical load is transmitted mainly through the columns.The vertical bearing capacity of the structure could be increased significantly by adopting new type section columns,which make it possible for low-rise cold-formed thin-wall steel residential buildings becoming high.At the same time,the effect of horizontal wind load and earthquake action are becoming more and more obviously.Therefore,it is necessary to improve the lateral resistance ability of the structure.The lateral stiffness can be improved effectively by installing braces,even the seismic performance of the whole structure does.In order to study the seismic performance of the cold-formed thin-walled steel residential buildings,the finite element model of the combined walls with 8 different arrangement of braces were established.Selecting the combined walls with good performance,the simplify models of the structure were went up.Based on that,seismic performance of the structure was analyzed.Combined wall with the size of 3m×2.4m finite element models(including a kind of comparison model without braces)were established by ABAQUS software.Under the action of low cyclic loading,the shear performance of composite wall was studied by finite element method.The influence rules of different braces on the shear capacity,stiffness degradation and ductility of the composite walls were obtained by changing the number,location and direction of the brace.The results were as following.Under the same number of inclined braces,the bearing capacity and ductility of the walls arranged on arrangement of braces,the inclined braces on the side of the wall were higher than those in the middle,and the stiffness degradation was slow.When the inclined braces were arranged continuously,the bearing capacity and ductility end to end were higher than that of the same direction,and the stiffness degradation was slow.When spacing the inclined braces,the bearing capacity of the arrangement of braces pointing to the wall’s corner was higher than the eight type arrangement,the ductility was slightly lower,and the stiffness degradation was close.Comparing the shear performance,stiffness degradation and ductility,4 walls with better performance were selected for the seismic performance analysis of the structure.Based on that,the SAP2000 software was used to establish the simplified models of the structure with 5 different arrangement of braces(including a kind of non-braced structure as a comparison model).The model analysis of each structure was carried out.The results showed that the first two modes of the structure were the translational mode,and the third order mode was torsion mode.The El Centro wave,Taft wave and Lanzhou artificial wave were selected,and the time-history analysis of each structure were carried out under the action of frequent earthquakes of 7 degree～9 degree and rare earthquakes of 7 degree～8 degree.(Each seismic wave included 10 working conditions,and there were 30 working conditions at all).By analyzing the structural acceleration response and displacement response,the influence of different arrangement of braces on the seismic performance of the whole structure was studied.The results of time-history analysis showed that the structure had shear deformation mainly(the interlayer displacement and displacement angle mainly decreased from 1 floor to 3 floor),and the first floor was the weak story,installing braces could improve the seismic performance of the whole structure effectively.In terms of the seismic performance of the whole structure,arrangement of inclined braces on the side of the wall end to end was the best,and on the side of the wall of the same direction timed,then,the two alternative arrangement of inclined braces on the side of the wall ranked third.The maximum interlayer displacement angle of each structure is 1/993,and the maximum elastic-plastic interlayer displacement angle is 1/98.Referring to the relevant provisions of the Code for Seismic Design of Buildings(GB50011-2010),as for new-type cold-formed thin-walled steel residential buildings,the limit of elastic interlaminar displacement angle was recommended to take 1/800,and the limit of elastic-plastic interlayer displacement angle was suggested to take 1/80.Based on an example of cold-formed thin-walled steel structure,a simplified model with the arrangement of braces on the side of the wall end to end was established.Time history of the structure was carried out by the El Centro wave,under the action of frequent earthquake of 9 degree and rare earthquake of 8 degree.The result of the time history analysis showed that the applicability of the conclusion was good.