Externally bonded and anchored engineered cementitious composite and glass fiber mesh strips for enhancing defected RC beams in shear
Galal Elsamak, Ayah A. Alkhawaldeh, Moataz Badawi, Emad Alshammari, Taher A. Tawfik, Mohamed Ghalla
Abstract
In light of the growing concerns over insufficient reinforcing details in reinforced concrete (RC) members, new innovative and effective strengthening techniques are essentially needed. Developing the behavior of RC beams using composite materials has gained potential in recent years according to their superior mechanical properties. This study introduces and evaluates a novel technique for strengthening shear-deficient RC beams using a combination of engineered cementitious composite (ECC) and glass fiber textile mesh (GFTM). The research focuses on experimentally and numerically assessing the effectiveness of externally bonding GFTM-ECC strips to the beam’s surfaces. The proposed method explores the influence of key design parameters, including the orientation angles of the strips (30°, 45°, 60°, and 90°), varying strip widths (60-, 75-, and 100-mm), and the presence of anchoring systems during installation. Finally, a parametric study covering the effect of varying reinforcement ratios of glass fiber mesh in strengthening the entire shear span was carried out. The efficiency of the strengthening methods was judged in terms of energy absorbed, elastic index, maximum deflection, ultimate load, cracking load, and failure mode. The results demonstrate that the GFTM-ECC system effectively delayed crack propagation and enhanced load-carrying capacity, achieving an increase in cracking load ranging from 27 % to 94 % relative to the unstrengthened defective beam (DB) across all investigated strengthening configurations. Moreover, the ultimate load capacity increased by up to 62 % compared to the defected beam. The failure modes shifted from sudden brittle shear failure to more ductile behavior, revealing improved energy absorption and delayed crack propagation. The use of anchors delayed the crack propagation and increased beam failure load levels. Ultimately, an analytical prediction for estimating the ultimate capacity of beams reinforced with GFTM-ECC strips was produced and was accurately verified by experimental results, provided that debonding failures are avoided. • New strengthening techniques are urgently needed for reinforced concrete (RC) members. • This study examines ECC and GFTM strips for reinforcing shear-deficient RC beams. • The method involves bonding fiberglass mesh with ECC mortar at angles of 30°, 45°, 60°, and 90°. • GFTM-ECC significantly delays cracking, boosting load capacity by 27–79 %. • Anchors further improved load levels and delayed cracks.