Behavior and design of slender square tubed-reinforced-concrete columns subjected to eccentric compression

This paper reports the studies on the behaviors of slender square tubed-reinforced-concrete (TRC) columns under eccentric loading. Eight specimens with the key parameters of length to width ratio (6, 10), load eccentricity (25 mm, 50 mm), and width to thickness ratio of the steel tube (133, 160) were tested. The test results indicate that the slender square TRC columns exhibit good ductile behavior during the eccentric loading with a global bending failure mode. A finite element (FE) analysis model was developed and the predicted results are in fine agreement with the test results. Parametric analyses were carried out to investigate the influence of the key parameters on the moment magnification factor of square TRC columns. Based on the test and parametric analyses, a regression formula of moment magnification factor is proposed to estimate the second order effect on the slender square TRC columns subjected to eccentric compression.