Contribution à l’étude du comportement sous chargement sévère des éléments renforcés de structures en béton armé

Abstract

Reinforced concrete (RC) beam-column joints (BCJs) are one of the critical structural members in buildings, often lacking adequate seismic detailing, which makes them vulnerable to brittle failure during earthquakes. This deficiency can lead to the collapse of an entire building under severe seismic loading. Retrofitting these joints is crucial for enhancing structural resilience. While fiber-reinforced polymer (FRP) composites have been widely used for this purpose, premature debonding from the concrete surface remains a major challenge. To mitigate this issue, concrete surface preparation using the grooving method (GM) has emerged as a promising technique, enhancing FRP-concrete bond and retrofit efficiency. This study numerically investigatesthe behavior of non-seismically designed BCJs retrofitted with carbon fiber-reinforced polymer (CFRP) sheets using the GM. A numerical approach is adopted using the finite element software ABAQUS, employing an explicit solver to accurately capture the nonlinear response of retrofitted joints. The concrete damaged plasticity (CDP) model is utilized to simulate concrete behavior, with a sensitivity analysis conducted on its key parameters. The FRP-concrete interface is modeled as a perfect bond, reflecting the strong adhesion provided by the GM. Numerical results are validated against experimental data from three BCJ specimens selected from the literature, showing good agreement in terms of load-displacement behavior, peak loads, and failure modes. Parametric analyses are conducted to evaluate the influence of key design parameters on the performance of retrofitted joints. These include column axial load ratio, beam reinforcement ratio, joint aspect ratio in conjunction with joint transverse reinforcement, and fiber type. Results indicate that CFRP retrofitting significantly enhances joint strength and ductility, particularly in joints with pronounced shear deficiencies. The study also highlights the critical role of these design parameters in governing joint shear capacity and, consequently, the effectiveness of the retrofitting technique