Eccentricity-based design procedure of confined columns under compression and in-plane bending moment

Abstract

Steel strapping tensioning technique (SSTT) has started to gain attention recently. The confining method using post-tensioned recycled steel straps allows high-strength concrete (HSC) columns to achieve higher ultimate strength and ductility. However, the experimental data and design method for SSTT-confined columns subjected to eccentric compression is still lacking and its behavior is needed to be clarified before it can be used confidently in the industry. In this paper, theoretical analysis was carried out considering various parameters such as eccentricity ratio, confining volumetric ratio and end eccentricity ratio of such columns. Experimental tests were carried out to validate the developed theoretical model. Finally, the equivalent concrete stress block parameters of circular SSTT-confined members are theoretically studied and the modified values are purposely suggested for the calculation of capacity interaction diagram. Comparisons between the proposed design equations with theoretical results showed accuracy as high as 95%.