Research On Mechanical Properties Of Split Cold-formed Thin-walled Steel Composite Columns

With the development of large-span and super high-rise buildings,and the rise of "fabricated" buildings,more and more buildings adopt the form of steel structure.Among them,cold-formed thin-walled steel has been widely used because of its light weight,various cross-section types and convenient assembly.The cold-formed thin-walled steel composite column with split section is combined with C-shaped steel and steel plate through rivets and poured with concrete,which enhances the bearing capacity and stability of the composite column.This paper adopts a combination of experimental research and theoretical analysis to study the mechanical properties of cold-formed thin-walled steel composite columns with split cross-sections,and lays the foundation for the application of such components in engineering.Axial compressive load is applied to specimens of cold-formed thin-wall steel lightweight concrete composite columns with single-limb split section,cold-formed thin-wall steel lightweight concrete columns with single-limb split section,and cold-formed thin-wall steel lightweight concrete columns with double-limb split sections.Analyze the stress state of each component,study the mechanical properties and failure modes of the specimen under axial load.The test results show that :(1)The failure form of cold-formed thin-walled steel hollow columns with single-limb split-section is mainly manifested as the local buckling of cold-formed thin-walled steel leads to the overall instability and failure of the component.Among the parameters studied,the wall thickness is the same as the cold-formed section of the split-section.The load-bearing capacity and deformation performance of thin-walled steel columns have a greater impact,and the size of its cross-section has no obvious effect on the bearing capacity;(2)The core concrete in the tube effectively limits the local buckling of the hollow column and improves the overall stability and ultimate bearing capacity of the component.And with the increase of section size and steel content,the ultimate bearing capacity of cold-formed thin-walled steel composite columns with single-leg split section also increases.On the basis of the experiment,through the finite element analysis of the cold-formed thin-walled steel composite column with split section,the influence of steel content,steel yield strength,cross-sectional area,etc.on the bearing capacity and seismic performance of members is studied.The results show that :(1)With the increase of section size,steel yield strength,and steel content,the ultimate bearing capacity of cold-formed thin-walled steel composite columns with split section also increases linearly.In the design of cold-formed thin-walled steel composite columns with split section,increasing the section size,increasing the yield strength and steel content of the steel can effectively increase the axial bearing capacity of the cold-formed thin-wall steel composite columns with split section;(2)The axial compression ratio has a greater influence on the horizontal bearing capacity of cold-formed thin-walled steel composite columns with double-limb split cross-section.As the axial compression ratio increases,the horizontal bearing capacity of the component decreases,and the slope of the stiffness of the descending section increases.