Study On Mechanical Behavior And Failure Mechanism Of Concrete-filled Circular Steel Tube Under Axial Compression

The so-called thin-walled steel tube concrete column is the cross-sectional diameter to thickness ratio D/t or width ratio B/t is greater than the corresponding pressure component hollow steel pipe local stability limit of 1.5 times in the building construction,especially high-rise building structure,Sectional size is generally larger,the cross-sectional diameter to thickness ratio D/t or width ratio B/t belongs to the definition of thin-walled steel pipe.In the actual project found that such thin-walled concrete-filled steel tubular column under the action of the load,the wall prone to local buckling.At present,in order to prevent the occurrence of local buckling of the pipe wall,there are mainly stiffening ribs,restrained rods and corner braces.These are mainly for concrete columns with rectangular steel tubes,and for concrete thin-walled concrete There are few studies that show that the hoop around the outer wall of the round pipe can retard the local buckling of the pipe wall and improve the ultimate bearing capacity of the concrete column.In this paper,the problem of local buckling of circular thin-walled steel tubular columns under axial compression is proposed.In the form of straight ribs,ribs and spiral ribs in the inner wall of steel pipe,the stiffening ribs and ribs The deformation capacity and mechanical properties of thin-walled steel tubular columns are studied,which mainly include the following aspects:For ordinary round steel tube concrete column,straight rib round steel tube concrete column,opening the round steel tube concrete column and the spiral round steel tube concrete column axial compression test,observation experiment phenomenon,analysis of failure mode and failure mechanism of the specimens;The load-deformation curve obtained from test analysis all specimens under the action of axial pressure steel pipe deformation and axial force of the longitudinal relations;Study these forms of stiffening rib on the circular thin-walled steel tube concrete column of ultimate bearing capacity,ductility and other mechanical performance index,the influence of provide the basis for the theoretical study.Using ABAQUS finite element analysis software to establish the common and straight ribs,opening straight tubes and finite element model of the helical rib round steel tube concrete column and the finite element calculation results with the test results,this paper compares and analyzes the correctness of the finite element model are validated,the parameter analysis of the specimen laid a foundation.On the basis of the finite element model is verified,the set screw circular thin-walled steel tube concrete column parameter analysis,mainly studies round steel tube diameter,thickness ratio of the parameters such as generous rate and pitch of the helical rib on its mechanical properties.