Abstract

Concrete-filled steel tubular structures have good mechanical performance and have been wildly used in civil engineering structures. Many researchers have already conducted study on it，but most research are mainly focused on concrete-filled steel tubular columns. And the thickness of the tubular wall is not exceed 6 mm. In this study, the research of cold-formed 6mm-wall and 10mm-wall square steel stub columns filled with concrete under axial pressure is presented. The conclusion of the research in this paper can provide some reference to the development of the study of concrete-filled steel tubular columns.

Based on the conclusion of the experimental research which is the mainly content of this paper, the column strength calculated using four standards and obtained from the finite element (FE) analysis were studied too. Ten specimens including 6mm-wall and 10mm-wall columns, involving five tubular sections, were tested.

According to the experimental study of the columns under axial pressure, we can obtain the ultimate strength and stress mechanism of the specimens. Based on the test result together with the standard methods and the FE analysis, the behavior especially the bearing capacity of the cold-formed medium-walled square steel stub columns with different sets of stiffeners and the thickness of tube wall is studied. And the finite element model is used to carry out analysis of the actual pier. Mainly conclusions are listed as follows:

1) More stiffeners can offer an increase in the strength of cold-formed medium-walled square steel stub columns filled with concrete. And reasonable arrangement of stiffeners can get ideal effect.

2) The design strengths calculated using CECS159:2004, DBJ 13-51-2003, AISC(2005) and BS EN 1994-1-1:2004 standards are all less than the experimental values. The result of AISC(2005) is the closest to the experimental values.

3) The finite element analysis is applicable to the simulation of the columns in this study.

4) Based on the FE analysis, the analysis of concrete-filled steel tubular pier was carried on. And the optimal concrete-filled steel tubular section size was found,