Research On The Design Method Of T-shaped Stiffener For Rectangular Concrete-filled Steel Tubular Colunmn With Large Width To Thickness Ratio

Compared with other section profiles,the rectangular concrete-filled steel tubular column has many advantages,such as being simple in joint structure,better architectural effect and larger bending rigidity,it had been widely used in high-rise buildings.However,for the rectangular concrete-filled rectangular steel tubular columns,the steel tube is prone to local buckling caused to decline of ultimate strength,and the confined effect of the steel tube is not uniform,the composite performance of rectangular concrete-filled steel tubular column is poor.In order to improve the local stability and composite performance of rectangular concrete-filled steel tubular columns with large width to thickness ratio,domestic and foreign scholars had proposed a series of construction measures,such as setting tensile sheets,binding bars,oblique ribs,straight ribs and steel bar stiffeners,It is shown that the reasonable stiffening can effectively improve the mechanical performance of rectangular concrete-filled steel tubular column.However,the previous studies had mainly focused on the influence of the reasonable stiffening on the rectangular concrete-filled steel tubular columns,while little research had been done on the local stability of the steel tube.In this paper,the longitudinal T-shaped stiffeners are arranged on the inside of the rectangular concrete-filled steel tubular columns with large width to thickness ratio,compared with other stiffeners,the T-shaped stiffener has higher bending stiffness,and the flange of the T-shaped stiffener is wrapped in the core concrete,which is beneficial to the common working performance of the internal concrete.In order to avoid the local buckling of the steel tube and ensure the composite performance of rectangular concrete-filled steel tubular column,the T-shaped stiffener design method is proposed.The following research work is carried out on rectangular concrete-filled steel tubular column with longitudinal T-shaped stiffeners.The theoretical analysis and finite element analysis are applied for the rectangular steel column with T-shaped stiffener of large width-thickness ratio,the results show that the local buckling stress of the steel tube is improved,the component occurs strength failure or overall instability failure.It is possible to break through the limit values of the width to thickness ratio for the steel tube,it can provide a theoretical basis for local stability analysis of the rectangular concrete-filled steel tubular column with large width-thickness ratio.And with rectangular concrete-filled steel tubular column of large width to thickness ratio as the research object,local stability of the component is analyzed by energy method,in order to meet the local buckling of steel tube behind the yield,the paper proposes T-shaped stiffener stiffness design method.For rectangular concrete-filled steel tubular columns with large width to thickness,on the basis of theoretical research,the rational design of T-shaped stiffeners.Through axial compression bearing capacity analysis by ABAQUS finite element software,the results show that the T-shaped stiffeners are reasonable and effective,steel tube with large width to thickness ratio occurs strength failure,the concrete strength is improved and the bearing capacity of the member is increased,and the bearing capacity of member strength and stability meet the standard recommended value.And the influence of the relevant parameters on the mechanica l properties of rectangular concrete-filled steel tubular columns with T-shaped stiffeners are analyzed,such as the width to thickness ratio of steel plates,the aspect rati o of section,the strength of steel,the strength of core concrete,the rigidity of T-shaped stiffener and slenderness ratio.Based on the finite element calculation results,the theoretical study on the calculation method of the axial bearing capacity of rectangular concrete-filled rectangular steel tube columns with no stiffeners and T-shaped stiffeners is carried out.