N-M AND M-K RELATIONSHIPS OF REINFORCED CONCRETE COLUMNS IN TEC2018

Abstract

Reinforced concrete elements subject to moment, shear and axial force due to different level of static and dynamic loads based on their location and material characteristics. These elements disseminate the loads based on their connections with other elements. In particular, each column in the structure exhibits "combined bending" behavior together with the resulting moment of the eccentric axial force exerted. In the case of the axial load acting on one of the symmetry axes (x or y axis) the uniaxial bending, and the axial load acting out of the symmetry axis, biaxial bending occurs. Also, since the structures are composed of two directional frames and slabs, the reinforced concrete columns are subject to combined bending effects in both directions. Therefore, the determination of the ultimate strength and behavior of the reinforced concrete columns depends on the interaction of axial force (N) and moment (M). In this study, the N-M diagram of reinforced concrete columns is given considering the section geometry, concrete and steel reinforcement strength and placement of the longitudinal reinforcements. The given N-M diagrams are prepared based on the axial force limits in codes. In addition, the N-e diagram showing the axial force and eccentricity relation of reinforced concrete column sections is given. Ductility ratios are given by plotting the moment curvature diagrams of the column sections at various axial force levels of the N-M diagram.