Assessment of FRCM jacket configurations for enhancing shear strength of deficient RC beams
Galal Elsamak, Mohamed Ghalla, Mohamed H. El-Naqeeb, Yahia Iskander, Rabeea W. Bazuhair, Saad A. Yehia
Abstract
Aging concrete structures and evolving load demands necessitate robust rehabilitation strategies, particularly for reinforced concrete (RC) beams highly susceptible to sudden, brittle shear failure. While Fiber-Reinforced Cementitious Matrix (FRCM) systems offer advantages over traditional externally bonded composites, a critical knowledge gap persists regarding the optimal configurations and the paramount role of anchorage in maximizing FRCM's effectiveness for shear strengthening applications. This study addresses this gap by comprehensively investigating the shear strengthening efficacy of various FRCM jacket configurations, both with and without anchorage, for deficient RC beams through experimental testing and validated numerical modeling. Nine RC beams were subjected to shear tests, including two controls and seven strengthened with one-sided, two-sided, U-wrapped, and fully wrapped FRCM jackets, incorporating both anchored and unanchored applications. Key performance indicators such as failure modes, ultimate load capacity, elastic stiffness, and energy absorption were rigorously assessed. A three-dimensional nonlinear finite element (FE) model was subsequently developed and validated against the experimental data to provide robust predictive capabilities. Results demonstrate that FRCM jackets significantly enhance shear performance. Notably, fully wrapped specimens achieved a remarkable 70 % higher ultimate load, 73 % greater stiffness, and an exceptional 356 % increased energy absorption compared to the deficient control beam. Anchorage systems proved crucial, consistently preventing premature debonding and maximizing the FRCM's contribution to shear resistance across all configurations. While one- and two-sided jackets provided moderate gains (12–39 % in peak load), U-wrap and full-wrap configurations delivered marked improvements (45–70 %), with full wrapping providing optimal performance. These findings unequivocally demonstrate that full wrapping and the integration of anchorage systems are paramount for maximizing shear resistance, delaying crack propagation, and transforming brittle shear failures into more ductile responses. The study offers crucial practical guidelines for optimizing retrofitting designs for deficient RC beams. This research significantly advances the understanding of FRCM system optimization, reinforcing its immense promise in structural rehabilitation and resilience applications.