Quasi-static tests of RC columns under variable axial forces and rotations

The behaviour of reinforced-concrete (RC) elements subjected to axial force and rotation variations in conjunction with lateral displacement variation is considered a highly important topic, but only a few experimental studies investigating this topic have been performed. In this paper, five full-scale RC rectangular columns were tested by quasi-static testing (QST) to investigate the effects of large variation axial forces and rotations on the seismic behaviour of columns. Furthermore, the effects of variable axial forces and rotations on the seismic performance of RC columns in terms of the failure modes, hysteretic loops, skeleton curves, ductility factors, stiffness degradations and energy dissipations are presented and analysed. Based on the QST results, the axial force and rotation variations have significant effect on the seismic behaviour of RC columns. Generally, the variable axial forces and rotations may cause a distinct asymmetrical failure phenomenon in the specimens and reduce the lateral strength and ductility factor. Thus, RC columns should be well designed to account for the adverse effects of variable axial forces and rotations.