STUDY ON FLEXURAL BEHAVIOR OF THE CONCRETE FILLED CIRCULAR CFRP-STEEL TUBE: EXPERIMENTAL STUDY

摘要

Sixteen concrete filled circular CFRP-steel tubular flexural members were tested and the test results are analyzed here. Load-mid span deflection curves for members without the longitudinal CFRP are similar to that of the concrete filled circular steel tubular flexural members, while load-mid span deflection curves for members with the longitudinal CFRP can be defined as following stages, e.g., elastic stage, elasto-plastic stage and softening stage. The increment ratio of the ultimate load carrying capacity increases as the longitudinal CFRP layer increases for members with the same confinement factor of the steel tube. The steel tube and the CFRP tube could cooperate longitudinally and circumferentially both from 0 loads to the ultimate load carrying capacity. At a given point, longitudinal tension must be in circumferential compression, and vice versa, and the steel tube that longitudinally tensioned has little confinement on the concrete core. From 0 loads to about 0.8 times the ultimate load carrying capacity, distribution of the steel tube longitudinal strain over the depth of the cross-section meets the plain-section assumption approximately. Longitudinal CFRP can enhance specimen's rigidity significantly.