EXPERIMENTAL RESEARCH AND THEORETICAL ANALYSIS OF SQUARE TUBE FILLED WITH REINFORCED CONCRETE SUBJECTED TO AXIAL COMPRESSION AND BI-AXIAL BENDING MOMENT

This paper presents an experimental research of 9 square steel tube columns filled with steel- reinforced concrete subjected to axial compression and bi-axial bending moment. The primary parameters of the specimens were slenderness ratio, eccentricity ratio, steel-reinforced ratio and angles of loading. The tested results showed that 1) the bearing capacity decreased with the increase of the slenderness ratio and eccentricity ratio; 2) increasing steel-reinforced ratio help to raise the bearing capacity gradually; 3) loading angle had little influence on bearing capacity. Furthermore, an analysis program was developed, which generates results agreeing well with the test data. At last, formula to calculate the bearing capacity of two-way eccentrically loaded columns are proposed.