Analytical Load Displacement Curves of RC Columns under Constant Axial and Cyclic Lateral Loads

The cyclic tests of the columns are of practical relevance to the performance of compression members during earthquake loading. The strength, ductility and energy absorption capabilities of RC columns, subjected to cyclic loading, have been estimated by many researchers. These characteristics are not normally inherent in plain concrete but can be achieved by effectively confining columns through transverse reinforcement. An extensive experimental program, in which performance of four RC columns detailed according to provisions of ACI-318-08, was studied in comparison with that of four columns confined by a new proposed technique. Out of total eight, this paper presents performance of three columns which were detailed according to provision of ACI-318-08 and cast with 25 and 32 MPa concrete. The experimentally achieved load-displacement hysteresis and backbone curves of the three columns are presented. Two approaches, which utilize moment-curvature and shear-shear strain relationship of RC columns achieved through Response-2000, have been suggested to draw analytical load-displacement curves of the columns. The experimental and analytical load-displacement curves are found in good agreement. The suggested analytical technique is simple and easy to implement. The technique will be available to the engineers involved in design to estimate capacity of RC columns.