The Theoretical Research On The Local Buckling Of Concrete-filled Steel Tubular Column Subjected To Axial Compression

Concrete-filled steel tubes structure can be divided into different section of the form of concrete-filled steel box columns, concrete-filled circular steel tubes and concrete-filled steel tubular polygon, and so on. When the concrete-filled steel box columns under axial compression, the steel tubes have the ability to confine the core concrete, and the core concrete prevents the steel tubes buckle inward, as a result, the local buckling capability is greatly enhanced. The local buckling occurs in the steel tubes of the long column of concrete-filled steel tube before its overall instability. The local buckling of the steel plates will reduce the ultimate load and ductility of the composite columns , then study of local buckling of steel tubes is especially important. This paper studied as follows:To begin with, introduction introduces the characteristics and development at home and abroad and application of concrete-filled steel tubes, and then introduced the study status at home and abroad of concrete-filled steel tubes.Moreover, the local buckling of the concrete-filled steel box columns under axial compression are analyzed in theory. the local buckling model of steel plate is determined according to the assumption that the core concrete is considered as a rigid body and the steel plate of concrete-filled square steel tubular column is subjected to spring constrain at the unloading edge. The formulae for calculating local buckling critical stress of the steel plate of rectangular concrete filled steel tubular column subjected to axis force are deduced using energy approach.In addition, the circular concrete-filled steel tubular columns are analyzed in theory. According to the interaction of steel and concrete, on the assumption that the core concrete is considered as a rigid body and steel tube strip elements supported by the rigid foundations, and the assumption that the core concrete is considered as a rigid body and generally cylindrical shell model, the formulae for calculating local buckling critical stress of the steel plate of concrete-filled steel tubular columns subjected to axis force are deduced respectively using energy approach.Finally, the buckling of inclined stiffeners with plates are studied. All edges simply supported rectangular plate subjected to biaxial uniform compression and uniform compression and shear forces with stiffeners are analyzed using energy approach.All edges simply supported rectangular plate subjected to pure uniform shear forces with inclined stiffeners are analyzed using energy approach. Conseque- ntly, stiffeners effects of the size of the buckling load.