The Behavior evaluation for reinforced concrete columns with rectangular hollow section subjected to axial compression and biaxial bending

In order to evaluate the behavior of reinforced concrete columns with rectangular hollow section subjected to axial compression and biaxial bending, the calculation formula of load capacity and moment-curvature relationship are derived according to the distribution type of neutral axis in this paper. The load capacity and rotation ductility of the bottom control section of three reinforced concrete specimen bridge columns with rectangular hollow section under different axial compression ratio, reinforcement ratio and stirrup ratio are analyzed based on these calculation formulae. The Mx–My interaction curves and moment-curvature curves of bridge column specimens derived from the theoretical calculation show good agreement with the experimental data obtained by cyclic testing of three specimens under axial compression and biaxial bending. The results show that the P–Mx–My interaction has considerable effects on the behavior of the reinforced concrete bridge columns with rectangular hollow section. If these interaction effects are ignored, then the load capacity and deformation are overestimated and this fact can be crucial from the viewpoint of design.