Cyclic performance of fire-damaged concrete-filled steel tubular beam–columns repaired with CFRP wraps

This paper presents the results of cyclic tests of fire-damaged concrete-filled steel tubular (CFST) beam–columns repaired by unidirectional carbon fibre reinforced polymer (CFRP) composites. The test parameters included the cross-section type (circular and square), the number of CFRP layers (1 and 2) and the axial load level (0–0.78). Based on the experimental measurements, the repair effects of CFRP wraps on the ultimate lateral strength, flexural stiffness, dissipated energy and ductility of the beam–columns are studied. The test results showed that the ultimate lateral strength, flexural stiffness and ductility can be enhanced to some extent due to the CFRP confinement effect. However, the strength and stiffness of all damaged specimens have not been fully restored in the current tests. Since there exist several possible solutions for the repair/strengthening of CFST members to restore/enhance their strength or stiffness, it seems that an appropriate evaluation method should be developed to make a suitable selection among them based on future comparative study.