Analysis Of Influence Factors To Local Buckling Of Square Concrete-filled Steel Tubular Column

In square steel tube columns, steel tube box achieves constraint to core concrete through the plane flexural capacity of steel plates. Because the plane flexural capacity of steel plate is relatively weak in the middle section, it is easy to buckle locally in the middle section. In order to analyze the factors that affect the local buckling, this paper made the following work:Firstly, this paper disintegrates the force endured by the steel plate of square concrete-filled steel tube column into one perpendicular to the neutral surface of steel plate and another parallel to the neutral surface of steel plate, simplifies loading sides and non-loading sides as fixed edges, and then suing energy principle, analyses factors influencing the local buckling of steel plate from the stress and deflection.Secondly, based on a great deal of experimental data, The next part of this paper, taking mostly influencing factors into account, attempts to deduce the critical local buckling bearing capacity formula of the square concrete-filled steel tube column by the method of multiple linear regression. By comparison, the results of multiple linear regressions accord with experimental results. The multiple linear regression formula provides a new method for forecasting and evaluating the local buckling critical bearing capacity of the square concrete-filled steel tube column. Based on the much experimental data, the formula has some dependability.Finally, the last part of this paper, using the powerful structure finite element analysis software ANSYS10.0 and considering simultaneously material nonlinear, geometry nonlinear and state nonlinear question, simulates the test of local buckling of square concrete-filled steel tube column through reasonable modeling, meshing and loading. Furthermore , this paper summarizes variation rule of local buckling critical bearing capacity be influencing by ration of width to thickness, ration of length to width , yield strength of steel and compressive strength of concrete. These accord with regression's results well. It is testified that the nonlinear finite element method is correct and feasible.