Cyclically and Biaxially Loaded Reinforced Concrete Slender Columns

Abstract

This study explored and examined the behavior of various cyclic compressive load levels on the ultimate strength, deflection, and moment-curvature characteristics of reinforced concrete (RC) slender columns with bidirectional eccentricities. Furthermore, a part of the research developed a numerical analysis that can simulate the behavior of RC columns under combined biaxial bending and cyclic axial compression. For the study, 4-ft (1.2-m) RC columns were tested under cyclic axial compression with bidirectional eccentricities. The main parameters of the column tests were the bidirectional eccentricities and its angle to the reference axis. The load pattern considered in the study was cyclical, and the applied load was a full loading of cycles that was loading up to the envelope curve and then unloading down to nearly zero stress level. The cyclic axial compressive load with bidirectional eccentricities considered was in the longitudinal direction, but not in the transverse direction, with respect to the column axis. The experimental ultimate load, load-deflection, and moment-curvature curves were compared with predictions from a computer model developed in the study. Results should provide guidance for structural engineers when they rehabilitate RC columns in building and bridge projects.