Numerical Investigation of Shear Response Lightweight Concrete Beams Strengthened with CFRP Reinforcement

Abstract This paper conducted a numerical analysis of the shear response of lightweight concrete (LWC) beams reinforced with carbon fiber-reinforced polymer (CFRP) reinforcement. An ABAQUS finite element (FE) model was developed and adjusted to the experimental data of Al-Allaf (2019). The model was in close agreement with tests, with ultimate load predictions within 9% and deflection predictions within 6.5%. In contrast to the majority of the current literature, which primarily deals with normal-weight concrete or flexural strengthening, the study fills the knowledge gap on shear performance of LWC beams reinforced with CFRP, which has been under-researched despite its practical importance in lightweight structures. The paper also investigated the influence of three parameters: concrete compressive strength (25, 40, and 55 MPa), CFRP modulus of elasticity (165, 240, and 640 GPa), and the number of CFRP layers (one, two, and three). Findings indicated that the ultimate capacity increased with concrete strength, which was 222.9 kN to 383.0 kN, and higher CFRP modulus enhanced stiffness but led to brittle rupture at very high values. The most significant factor was the number of CFRP layers, where the ultimate capacity was increased by up to 39 percent when three layers were used. The results indicate the precision and effectiveness of calibrated FE modelling as a cost-effective substitute to full-scale testing and offer practical advice on how to optimize CFRP retrofitting approaches in shear-critical LWC beams.