Abstract
The flexural behavior of two circular hollow reinforced concrete columns, with different longitudinal reinforcement ratios, under cyclic loading is investigated through a discussion of experimental studies. Test results showed that the columns were significantly failed when the inside concrete was crushed. It was also found that confinement-induced transverse strain at the plastic hinge region did not reach the yield strain before failure. Furthermore, moment-curvature analyses were carried out for the test units, to evaluate the lateral force-displacement response. The stress-strain curve of the confined concrete was calculated with an assumption that the maximum effective lateral pressure occurred when the spiral strain reached a maximum useful confinement-induced strain of 0.001. As a result, the theoretical force-displacement relation showed a good agreement with the experimental response.
