Study On Special-shaped Column Composed Of Concrete-filled Square Steel Tubes

Special-shaped column composed of concrete-filled square steel tubes (SCFT) is a new type of structural member. It is formed by connecting concrete filled square steel tubular columns with lacing bars. It combines the advantages of both concrete filled steel tubular column and special-shaped column, namely, it has better bearing capacity, earthquake resistance and fire resistance, and can be made to flexible section, easy to trim and save space. With these characteristics, SCFT extremely suit to the multilayer house, and will have a great foreground.For calculation method, the superposition theory is introduced, which is of simple calculation, of clear conception, and reliable safe, is verified to be suitable for the calculation of concrete-filled square steel tubular column. According to distributing coefficients of axial pressure, equivalent slenderness ratios and increasing of bearing capacity of steel tube, the paper deduced the calculation method of superposition theory for axially compressed SCFT.Analysis on SCFT under axial load with the finite element analysis software ANSYS is performed. The results are analyzed and compared with those of the theory developed before, which verify the accuracy of the superposition method.For SCFT, T-shaped and X-shaped column specimen are designed for axially compressed experiment in order to analysis load bearing capacity of strength failure, and of buckling failure. Results of ANSYS, superposition theory, and axially compressed experiments are concordant so that the feasibility of superposition theory for calculating SCFT is verified.The structural system for a steel structure dwelling house is created, the analysis on internal force and deformation of the construction under some load cases and combinations are performed, the analysis results have verified that SCFT has a better bearing capacity and earthquake resistance. The paper also compares the new style wall plate which suit to the residential construction.At last, the author puts forward several problems for Special-shaped column composed of concrete-filled square steel tubes to be researched more deeply and makes an expectation of them.