THE DESIGN OF SLENDER RC COLUMNS

Abstract

The paper presents the design method for slender reinforced concrete column based on design code EC2. Rarely, when the column height is longer than typical story height and/or the column section is small relative to column height, secondary stresses become significant, especially if end restraints are small and/or the columns are not braced against side sway. The expressions given in this paper for the additional moments were derived by studying the moment and curvature behavior for a member subject to bending plus axial load. The equations for calculating the design moments are only applicable to columns of a rectangular or circular section with symmetrical reinforcement. The slender column should be designed for an ultimate axial load plus an increased moment. The slenderness effect must be considered in design, over and above the sectional capacity considerations incorporated in the interaction diagrams. Results indicate the behavior of slender columns and the difference with short columns.