Seismic behavior of RC cross-shaped column under combined torsion loading: Experiment and simulation finite element

Abstract

The seismic behavior of the reinforced concrete (RC) cross-shaped columns under the combined action of compression, bending, shear, and torsion were studied by experiment and numerical simulation. The effects of torsion-bending ratio (T/M) and axial compression ratio (n) on the seismic indexes, i.e., failure modes, skeleton curves, hysteretic curves, strength, ductility and stiffness were studied. Experimental results suggested that the T/M ratio determines the failure modes of RC cross-shaped section columns. Both the damage length and crack angle increase with the raise of the T/M ratio. The displacement ductility factor and elastic–plastic drift ratio are higher than 3.0 and 0.02, respectively, indicating that the RC cross-shaped columns exhibit good ductility and deformation capacity under combined torsion loading conditions. The normalized shear-displacement hysteretic model and the torque-twist angle hysteretic model were established. Based on the experimental results, as well as the finite element model for RC cross-shaped columns under combined torsion, was proposed. The results derived from the hysteretic models and finite element simulation are in good agreement with the experimental results.