Analysis On The Behavior Of Rectangular Concrete Tube Filled Double Skin Under Axial Compression

Concrete filled double skin tubes (CFDST) consists of two concentric steel cylinders or shells with the annulus between then filled with concrete. It is a new form of concrete-filled steel tube structure, which has much good performance, such as unfolding cross-section, high flexural stiffness, light weight, good fire resistance and so on. However, so far the research project on CFDST has only been running more than ten years. And the section shapes are mostly square and circular.This paper reports the behaviors of rectangular concrete tube filled double skin tubular (RCFDST) under axial loads. The research work is summarized as follows:(1) Based on a great deal of experiments, and taken mostly influencing factors into account, I attempt to deduce the axial limited load-carrying capacity formula of the RCFDST 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 RCFDST. Furthermore, this method avoids complex process of mechanics analysis. Based on a great deal of experiments, the formula has some dependability.(2) Based on the many experiments, the next part of this paper, using the powerful structure finite element analysis software ANSYS, considering material non-linear and geometry non-linear question simultaneously, simulates the test of RCFDST short column under the axial pressure through reasonable modeling, mesh and correct loading manner. And, deduce the limited bearing capacity of the experimental component. Furthermore, I summarize the influence rule of bearing capacity and ductility behavior by hollow ratio, restriction coefficient. Besides, the experimental member's inherent mechanism and destroy mechanism are also analyzed. The results accord with experiment tests well. It is testified that the nonlinear finite element analysis method is correct and feasible.