| Cold-formed thin-walled steel Built-up section columns by basic C and U section which was connected with the self-tapping screw,this article designed the multiple built-up cross section column axial compression test,the axial compression buckling performance of the component type and bearing capacity were studied,and according to the test specification improvement design method is to put forward.Four types and six length of cold-formed steel columns axial pressure test were designed.For specimen installation form,test equipment,test methods,specimen buckling failure mode and the test results were observed and,axial compression columns’ buckling shape and failure mode were analyzed depending on the physical parameters of the bearing capacity.On the test results,the load-vertical displacement,the load-horizontal deflection,loadstrain were analyzed.The experiment ultimate load Pu was divided by effective section area Ae calculated by the Chinese specification getting a σi.Then this stress was devided by the material yield strength σy,getting a unitary stress ratio parameter c,which was used to discuss how the size of the effect of composition of built-up cross section.The experimental results showed that the four kinds of cross section in this experiment peforms greater capacity than that of singlelimb cross-sections.On the basis of the test and analysis of the results of the study,China and the United States of cold-formed thin-walled steel specification with effective width method and direct strength method to calculate has carried on the theoretical research.For 2-limbs and 4-limbs combination section strength reduction method was proposed,so as to make the specification design valuation more appropriate.Through comparing with the test bearing capacity analysis,verifing the feasibility method to calculate this built-up section columns,providing design axial compression bearing capacity calculation method of cross section column with the proper advice. |
