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

Based on experimental study and stress-strain relationship of the concrete confined by circular CFRP-steel tube under axial load, the moment-curvature curves of the concrete filled circular CFRP-steel tubular flexural members are analyzed using the fiber element approach, and the results predicted agree well with those of the tests and are on the safe side. Influences of the longitudinal CFRP layer and outer diameter of the steel tube on static performance of the concrete filled circular CFRP-steel tubular flexural members are analyzed. The typical moment-curvature curves of the concrete filled circular CFRP-steel tubular flexural members are proposed and the features of which are summarized too, for members with the longitudinal CFRP, the curve could be defined as the following three stages, e.g., elastic stage, elasto-plastic stage and softening stage, and for members without the longitudinal CFRP, the curve could be defined as the following three stages, e.g., elastic stage, elasto-plastic stage and plastic strengthening stage.