Feasibility of suppressing debonding failure for CFRP-hollow section steel tube composite member with a thick-walled section under tensile loading

Abstract

Carbon fiber reinforced polymer (CFRP) is extensively utilized to strengthen steel structures. However, the premature debonding failure of CFRP inhibits its validity in strengthening tensile steel structures. Accordingly, the introduction of a thick-walled hollow section steel tube located at both ends of the CFRP-hollow section steel tube (CFRP-HSST) composite member was developed for the strengthening of tensile members. The steel tube in the novel composite member is constituted of a middle thin-walled section and a pair of thick-walled sections at each end providing anti-debonding resistance. The strengthening efficiency of the novel composite member under axial tensile loading was experimentally investigated by 8 specimens, comprising 4 circular cross section and 4 square cross section composite members. It was found that the presence of thickened section could achieve the stress gradient of CFRP and distribute the adhesive's interfacial shear stress. In addition, the finite element model (FEM) of the proposed CFRP-HSST composite member was developed and examined the adhesive damage distribution and evolution, and subsequently, a parametric analysis was carried out. The results indicate that the novel CFRP-HSST composite member can be regarded as an efficient strengthening solution for suppressing the premature debonding failure as well as increasing the strengthening efficiency.