Experimental investigation on shear capacity of steel reinforced concrete columns under combined torque

To investigate the shear capacity of solid-web H-shaped steel reinforced concrete (HSRC) columns under combined torque, seven HSRC columns were tested using axial compression ratio (n), torsion bend ratio (gamma), and shear span ratio (lambda) as test parameters. The stress process and failure mode of the HSRC column were observed and recorded. The load-displacement (P-Delta) hysteresis curve and skeleton curve of each specimen were analyzed. The influence of three parameters on the shear capacity of the HSRC column was discussed. And revealed the shear mechanism under different failure modes of the HSRC column. The calculation formula of the shear capacity of the HSRC column was derived. The results show that the failure modes of HSRC columns under different parameters could be classified as bending-torsion-bending failure, torsion-bending failure, and torsion-shear-bond failure. The addition of H-shaped steel can effectively inhibit the development of the inclined crack and improve the shear capacity of the specimen. The P-Delta hysteresis curve of the specimen is full spindle. Increasing the axial compression ratio will increase the shear capacity of the specimen, but increasing the torsion bend ratio and shear span ratio will decrease. Finally, based on the calculation theory of normal section and inclined section bearing capacity, the calculation formulas of shear bearing capacity of HSRC columns under two kinds of composite torque are proposed for different shear span ratios. The calculation results are in good agreement with the experimental values.