EXPERIMENTAL INVESTIGATION ON SLENDER STEEL REINFORCED CONCRETE COLUMNS WITH MONOSYMMETRIC CROSS-SHAPED STEEL UNDER ECCENTRIC LOADING

To study the eccentric compression performance of slender steel reinforced concrete columns with monosymmetric cross-shaped steel, eight specimens were subjected to eccentric loading. The effects of the cross-shaped steel eccentricity ratio and the load eccentricity ratio on the failure pattern, lateral deflection, load-lateral deflection curves and ultimate strength were studied in different eccentric directions. A computational method for the normal section strengths of slender steel reinforced concrete columns with monosymmetric cross-shaped steel is proposed. The specimens exhibited small-eccentricity compression failure and large-eccentricity compression failure according to the different load eccentricity ratios. The cross-section strain conformed to the plane section assumption. The ultimate strength and deformability of the specimens decreased with the increase of cross-shaped steel eccentricity ratio in the positive eccentric direction. In the negative eccentric direction, the cross-shaped steel eccentricity ratio had negligible effect on the eccentric compression performance of the specimens failed in small-eccentricity compression. With the increase in the cross-shaped steel eccentricity ratio, the ultimate strength of the specimens failed in large-eccentricity compression increased slightly. The initial stiffness and the ultimate strength of the specimens decreased with the increase of the load eccentricity ratio. The monosymmetric cross-shaped steel is equivalent to the H-shaped steel in a safe way, and the eccentric strengths of the transformed section specimens calculated by JGJ 138−2016 are conservative. The eccentric strengths of the specimens calculated by the proposed method agree well with the test results.