Concrete Filled Steel Tubular (single Limb, Both Limbs) Column Stability Studies

The concrete-filled steel tubular (CSFT) column is superior to other structures in high bearing capacity, technology and economy. Because of these advantages, it has been adopted in industry factory and high rise buildings widely. Therefore the domestic and international scholars have carried on by many researches on mechanics performance and design method of the concrete-filled steel tubular structures. On the basic of concrete-filled steel tubular columns theory, the influence of member stability is analyzed, and formulas of stability are established. The main contents are listed as follows:1. The review of the bearing capacity of concrete-filled steel tubular was summarized and the curve of stress-strain of steel and concrete was selected. Concrete-filled steel stub tubular and moderate long columns are analyzed with finite element model.2. On the basic of parameters analysis, the capacity of concrete-filled steel tubular moderate long columns is founded, and axial concrete-filled steel tubular moderate long columns formula is established. Eccentricity ratio of concrete-filled steel tubular was analyzed, and eccentricity of concrete-filled steel tubular was established. Finally, the formula of concrete-filled steel tubular considering of slenderness ratio and eccentricity was established.3. On the basic of concrete-filled steel tubular moderate long columns theory, axial concrete-filled steel columns of initial stress was analyzed. The formula of CFST was established, considering the steel ratio, strength of steel and concrete, slenderness ratio.4. According to the principle of virtual work, the modified column slenderness ratio of CFST, the formula of modified slenderness was established. The capacity of concrete-filled steel tubular laced columns was analyzed, considering the influence of slenderness, tie length and tie layouts. The infection of local bucking and whole bucking interactional was considered, and double concrete-filled steel tubular laced columns was established.