| Although a series of experimental studies,numerical simulation analysis and theoretical analysis have been carried out on the stability of cold-formed thin-walled steel members at home and abroad,it was mainly aimed at the research work of solid member and composite columns,Besides,the section form is concentrate on simple section and non-complex lipped channel steel.The research results of complex crimped C-shaped steel battened columns are still relatively few.Moreover,the calculation method of the existing specification for the bearing capacity of the cold-formed complex crimped Cshaped steel double-limb battened columns is still to be verified.In particular,there is no provisions in direct strength method for built-up columns.Thus,it’s an urgent problem in cold-formed thin-walled steel structure that how to apply direct strength method to the design of built-up columns.In this paper,the axial compression performance and ultimate bearing capacity of cold-formed complex crimped C-shaped steel double-limb battened columns were studied by experiments and finite element variable parameter analysis.Firstly,20 cold-formed thin-wall complex crimped C-shaped steel battened columns were studied under axial compression test.The failure mode,ultimate bearing capacity and deformation characteristics of cold-formed thin-wall complex crimped C-shaped steel battened columns were studied.The test results showed that the specimens with high web height,the failure mode was dominated by the local buckling of the component and accompanied by the overall buckling of the specimen around the weak axis;With the increase of slender-length ratio,the failure mode of the specimen changed to the global buckling around the weak axis,without obvious local buckling.Secondly,the finite element analysis of the axial compression performance of coldformed thin-wall complex crimped C-shaped steel was carried out.First of all,on the basis of the test,the finite element model was adopted to carry out the numerical simulation analysis according to the measured dimensions of the test.By comparing the numerical simulation results and the test results(including the instability mode,the ultimate bearing capacity of the test specimen and the axial displacement curve of the load),verified the reliability and rationality of the finite element model.Then,through the parameter analysis of the axial compression performance parameters of cold-formed thin-wall complex crimped C-shaped steel battened columns,the influence of plate thickness and battened distance on ultimate bearing capacity of members with different slenderness ratio were discussed.The results showed that with the increase of slenderness ratio,the ultimate bearing capacity of the same section was decreasing gradually;With the decrease of the thickness of the member,the bearing efficiency of the member decreases gradually;When the battened distance is between 167 mm and 434 mm,the ultimate bearing capacity of the components did not change much.Therefore,it was reasonable to take a battened distance of 300 mm.Finally,the calculation method of axial bearing capacity of cold-formed thin-wall complex crimped C-shaped steel battened columns was studied.By comparing the calculation results by effective width method from GB50018-2002 and by direct strength method from CSA-S136-16 with numerical simulation results,this paper analyzed and evaluated the applicability of the existing domestic and foreign specification to the builtup battened columns.The analysis results showed that the calculation results of GB50018-2002 and CSA S136-16 are higher than the finite element analysis values in most cases,which are generally unsafe.On this basis,based on the finite width method and the direct strength method,the calculation formula of the axial bearing capacity of cold-formed thin-wall complex crimped C-shaped steel battened columns was proposed.The calculation results of the proposed formula agree well with the results of the finite element analysis results. |
