Strip-based numerical analysis of CFRP-reinforced steel plates with multiple debonding defects using the Runge-Kutta method.

• Study the bond behavior of CFRP-repaired steel plates with initial debonding defects. • A strip-based numerical method using the explicit 4th-order Runge-Kutta technique was proposed. • Single-lap shear test was simulated via FEM combined with cohesive zone modeling. • The effects of bond lengths and defect locations were discussed. In recent years, carbon fiber-reinforced polymers (CFRP) have earned extensive attention in the field of structural rehabilitation. Adhesive bonding, as a prevalent technique, plays a crucial role in utilizing CFRP for strengthening steel structures. Nevertheless, debonding defects, commonly arising within the bond region between CFRP and host structures, hold the potential to induce the premature debonding failure of adhesively bonded joints. As a result, this research attempts to propose a strip-based numerical method using the explicit 4th-order Runge-Kutta technique (strip-based RK4) to investigate the full-range bond behavior of CFRP-to-steel single-lap joints with multiple arbitrary debonding defects. Also, three-dimensional (3D) finite element models (FEMs) of fully bonded single-lap joints were established in conjunction with cohesive zone modeling (CZM) to simulate the single-lap shear test reported in literature, based on which joints containing debonding defects were further modeled. Predictions from the proposed methodology were subsequently compared with test results and FE analysis to confirm its accuracy. Thereafter, the parametric analysis was carried out to investigate the effects of parameters, including bond length and defect position, on the bond behavior of the single-lap joint. The results indicate that the proposed strip-based RK4 method is accurate, with errors within 2% compared to FE analysis, and computationally efficient, with runtime being less than 50% of FE analysis. The findings of this study can be used as a guide for the design or damage assessment of CFRP-repaired structures in the future. [ABSTRACT FROM AUTHOR]