Analysis On The Behavior Of Concrete-filled Square Steel Tubular Stub Columns Under Axial Compression

Because the structure of concrete-filled steel tubular (CFST) can take advantages of the two kinds of material of steel pipe and concrete adequately, nowadays, it has already been widely used in the engineering practice. However, the section shapes are mostly circular and rectangular. Though the restriction effect to core concrete of the steel tubular of concrete-filled square steel tubular is not as good as concrete-filled circular steel tubular, concrete-filled rectangular steel tubular has many advantages, such as its convenience of connecting with beams, good ductility, fire-resistance, and shearing force -resistance, so on and so forth. Because of that, people have become to attach importance to it. As the restriction between the tubular and core concrete of the concrete-filled square steel tubular is complicated and it is difficult to deduce the limited carrying capacity in theory. If the restriction between the tubular and core concrete is ignored, the advantage of this structure will be deduced. This article has systematically compared the calculate theories of square concrete-filled steel tubular short column, and has analyzed hypothesis and problem adopted by these formula. Based on a great deal of experiments, and taken mostly influencing factors into account, this article attempts to deduce the limited load-carrying capacity formula of the concrete-filled square steel tubular column by the method of multiple linear regressions. This method provides a new idea for forecasting and evaluating the limited load-carrying capacity of the rectangular concrete-filled steel tubular. Furthermore, this method avoids complex process of mechanics analysis.Based on many experiments, the next part of this article, considering material non-linear and geometry non—linear question simultaneously, simulates the test of square concrete-filled steel tubular short column under the axial pressure through reasonable modeling and correct loading manner and deduces the limited bearing capacity of the experimental component by the structure finite element analysis software ANSYS9.0. Furthermore, this article summarizes the rule of the influence on bearing capacity improvement by ratio of concrete compression strength, steel strength and restriction coefficient of experimental members. Besides, it analyzes experimental member's inherent mechanism and destroying mechanism which accord with experiment results well. It is testified that the non—linear finite element analysis method is correct and feasible.