Experimental study on seismic behavior of steel angle truss reinforced concrete columns under compression-bending-shear-torsion combined action

This study discusses the seismic behavior of steel angle truss reinforced concrete (SARC) columns under compression-bending-shear-torsion combined action. Ten SARC columns were designed and tested to investigate the influence of the axial compression ratio, torsion-bending ratio, shear span ratio, volume ratio of steel plates, and cover thickness. The failure modes and hysteretic curves of specimens were obtained in the test. The important performance parameters of the specimens were compared to evaluate the seismic performance of the specimens, including bearing capacity, stiffness degradation, ductility, and energy dissipation. The results show that the failure modes of SARC columns could be classified as bending failure, bending-torsion failure, shear-torsion failure, and torsional failure depending on the torsion-bending ratio and shear span ratio. An obvious "pinch" effect can be observed in the middle of the T-& theta; hysteresis curves of specimens, but the P-& UDelta; hysteresis curves are full. The torsional capacity of SARC columns can be improved by adding the axial compression ratio, torsion-bending ratio, and volume ratio of steel plates, but the effect is adverse when increasing cover thickness and shear span ratio. Moreover, a calculation method of torsional bearing capacity of SARC columns under compression-bendingshear-torsion combined action was proposed.