Improvement of the anti-debonding performance of CFRP-steel circular hollow section with conical-shaped CHS under tensile load: a finite element analysis

To strengthen the interfacial bonding performance of CFRP-steel circular hollow section (CFRP-SCHS) composite members under tensile load, an improved CFRP-SCHS composite member with a conical-shaped circular hollow section was developed in the present study. Refined parametric finite element models were established to provide comprehensive insight into the interfacial load transmission mechanism of the improved CFRP-SCHS. The effects of CFRP sheet thickness (t_c) and the configuration of the conical section (L₀ and t₀) on the interfacial bonding strength of the improved CFRP-SCHS were studied. The FE analysis results revealed that the conical-shaped section has a great influence on the anchoring performance of the CFRP-SCHS. Compared with the conventional CFRP-SCHS, the undesirable failure mode of steel tube yield at loading end can be effectively avoided and the maximum decreases of the interfacial peeling and shear stress decreases is 71.6% and 71.5% respectively. The effective bond length can be adjusted according to the length of conical-shaped section, which improves the uniformity of stress distribution. The elastic bearing capacity (P_y) of the improved CFRP-SCHS was mainly controlled by the yield strength of the thin-walled steel tube, the number of CFRP layers, and the conical rate of the conical section. The elastic and ultimate load-bearing capacity can be achieved by up to 27.8% and 191.7%, respectively.