Résumé:
This research investigates the effect of longitudinal rectangular holes on the bending capacity of T-beams constructed with reinforced concrete (RC), especially when they undergo strengthening or retrofitting using external laminates made of carbon-fiber-reinforced polymer (CFRP). The study involved eight RC T-beams, organized into four groups, each comprising one hollow and one solid beam. A three-point bending experiment was employed for a comprehensive examination of these beams. All beams were consistently equipped with an identical CFRP laminate and shared the same longitudinal reinforcement ratios. The experimental results showed that the ultimate load-bearing capacity of strengthened hollow RC T-beams was reduced overall by 9% in comparison with solid RC T-beams. In contrast, retrofitted hollow RC T-beams, subjected to 100% preload, showed a 24% decrease in ultimate load bearing capacity versus retrofitted solid RC T-beams. In particular, CFRP laminate has been shown to reduce strains in hollow T-beams effectively compared with solid beams. Retrofitted hollow RC T-beams showed a decrease in flexural efficiency post-preloading, despite the fact that strengthened solid RC T-beams and CFRP-strengthened reinforced concrete hollow T-beams with a 5% hollow cross-section displayed largely similar bending behavior. To enhance our understanding, a numerical model was developed in ABAQUS, providing an accurate simulation of hollow RC T-beam behavior. Subsequently, the validated model was employed in a parametric study to explore the impact of changing the size and location of the hollow section on the response of RC T-beams.
