Study On Axial Compression Behavior Of Concrete Filled Steel Tubular Z Section Columns

In recent years,with the improvement of human living standards,people's quality of buildings has also been improved.For example,the demand for housing function is not only satisfied with traditional thermal insulation,shelter from wind and rain,but now it is gradually pursuing its safety,comfort and beauty.The frame structure is currently often used in high-rise buildings,in people's daily use of the process,the frame structure slowly revealed a problem,namely: because the column with the thickness of the wall is not the same as(often column thickness),resulting in the column and wall at the junction of a prominent corner.On the one hand,the angle affects the aesthetics,on the other hand,it also reduces the effective use area of the building.In order to solve this problem,the researchers put forward the special-shaped section columns(T,L,ten and Z).In real life,the special-shaped columns have been applied in small high-rise buildings.Our country also promulgated the technical specification for concrete special-shaped columns in August 1,2006(JGJ149-2006),including T,L and ten section columns.The Z shaped section is also a special section.It can solve the problem of space dislocation,but its research is relatively few.Meanwhile,because the special section weakened the section area of the column,its bearing capacity has been reduced,so that it failed to make it widely used in high-rise buildings.From a large number of studies at present can be seen,concrete-filled steel tube structure can improve the bearing capacity of the components effectively,so this paper research on steel pipe concrete Z shaped column,one can solve the wall column between the edges,on the other hand can increase the bearing capacity,so the use of Z shaped columns better in high-rise and super high-rise go to the building structure.By making 6 concrete filled steel tubular Z section columns and 1ordinary concrete Z shaped columns,two variables of different steel plate thickness and stiffener are selected to study the axial compression performance.In this experiment the failure form,the component force curve of plate,vertical and horizontal analysis to the strain research,combined with the finite element software with experimental parameters and reasonable constitutive model,boundary conditions and loading mode modeling and analysis,finally draws the following conclusion:(1)steel pipe concrete Z shaped column under axial compression.The load displacement curves and the conventional concrete filled steel tube columns(circular and square)linear trend is similar to that of the component failure mainly to the end or ends at 100mm-150 mm below the main plate guqu.(2)the thickness of the steel pipe has a great influence on the axial compression bearing capacity of the members.When the thickness of the steel tube increases from 3mm to 4mm and 3mm to 5mm,the axial compressive bearing capacity of the stiffened members increases by 57.2% and 75.7%,respectively,and the axial bearing capacity of the stiffened membersincreases by 54.6% and 76.9% respectively.(3)the same as the thickness of steel tube under non stiffened(welded steel sheet as small stiffeners)bearing capacity have little influence on the ultimate,thickness of steel tube are respectively 3mm,4mm,5mm,relative to the non stiffened components were increased by2.1%,3.8%,1.4% bearing stiffener member.(4)relative to the non stiffening ribs,the ductility of the stiffened ribs increases obviously in the later stage,and can effectively limit the local deformation of the component.(5)On the basis of comparison and analysis of the existing domestic and foreign normative formulas,this paper considers the revised AISC(2005)formula in the United States,and puts forward the formal modification of the axial compression bearing capacity of Z shaped columns of concrete filled steel tube,in which the axial compressive strength N0 of the component is modified(revised detailed 6-9).