Behavior and strength of circular concrete-filled tube columns

The behavior of concrete-filled tube columns under seismic loads was studied by testing six columns which were subjected to a constant axial load in addition to a cyclic lateral load. The test parameters included the level of axial load, the diameter-to-thickness ratio of the steel tube, and the concrete compressive strength. The test columns showed high ductility and maintained their strength up to the end of the test. The test results also indicate that the column capacity was significantly improved due to the concrete strength gained from the confinement provided by the steel tube. An analytical model was developed to predict the capacity of circular CFT beam-columns accounting for the interaction between the steel and concrete. The analytical model is compared with the experimental data reported in this paper and those reported by other researchers. Good agreement was observed between the predicted values using the proposed model and the experimental results. (C) 2002 Published by Elsevier Science Ltd.