Mechanical Behavior And Bearing Capacity Analysis Of Concrete-Filled Double Skin Stell Tubular Columns With Circular Section

Concrete Filled Double Skin Steel Tubes(CFDST) is between the steel tube placed in two concentric filling concrete formation. The interaction of hollow sandwich steel tube concrete column makes full use of two kinds of material of steel tube and concrete in the process of stress, having the advantages of high bearing capacity, good plasticity and tenacity, convenient construction, good fireproof performance, characteristics of economic effect is good. Compared with traditional concrete filled steel tubular column, hollow interlayer steel pipe concrete column and its new features:section to carry out, the bending stiffness,light weight, good seismic performance.For the hollow interlayer steel pipe concrete column of square steel tube squareness outside, there exist some restriction effect on the core concrete constraints, but mainly concentrated in the four corners, away from the buckling stress of the position is relatively small, even in the elastic segment. Give full play to the material propertiesto consider, this paper intends to inner, outer tube are all circular component were studied, for ease of exposition, the paper called the circular hollow steel pipe concrete column. The main work contents:1. Based on fiber element method, For the behavior of CFDST columns with circular section under axial compression members under monotonic loading, the load-deformation of the whole process of the relationship were calculated and experimental results were compared and analyzed.2. The nonlinear numerical simulation analysis was conducted to investigate the mechanical behaviors of CFDST columns with circular section under Axial compression by ANSYS software and the calculated results were agreed well with the experimental ones. The results show that the 3D finite element analysis model is effective. The failure mode of plates was analyzed using the model. Furthermore mechanical behavior of axial compression column were studied corresponding to different parameters such as the outer diameterto thickness ratio, Slenderness ratios, Nominal steel rate, Hollow rate.3. By using the method of analysis and modeling of the same, CFDST columns with circular section under eccentric compression load deflection curve,inside and outside of steel tube and concrete strain distribution etc.Furthermore mechanical behavior of eccentric compression column were studied correspondingto different parameters such as core-concrete strength grade, thickness of the outer steel pipe, slenderness ratios, eccentricity ratios and the results provided some useful references for engineering design.4. The method based on the unified strength theory was used to calculate ultimate bearing capacity of CFDST columns with circular section under axial compression and eccentric loading. Compared the results with the experiment date and the solution of finite element, the results show that the method based on the unified strength theory can forecast ultimate bearing capacity of concrete-filled double skin stell tubular columns with circular section under axial compression or eccentric loading and this is tend to safety. Finally, reliable bases for engineering design are presented.