Impact of anchored CFRP on the torsional and bending behaviour of RC beams

The scientific problem considered in the study is indeed one of the problems in the modern theory of reinforced concrete. Despite a significant number of studies on the problem of bending with torsion, to date. There are no sufficiently reliable solutions to this problem that most fully reflect the physical nature of the problem. In the last two decades, using of Carbon Fiber Reinforced Polymers ( CFRP) in strengthening of deficient reinforced concrete structural elements has been increased due to their ease of installation, low invasiveness, high corrosion resistance, and high strength to weight ratio. Strengthening damage structures is a relatively new technique. Therefore, the intent was to appear at the essential CFRP external strengthening technique that provides an efficient increase in the shear and flexural strengths as maintaining ductile failure mode. However, anchoring and debonding problems remains a challenge for the accomplishment of this technique. In this study, a novel application was implemented in which the CFRP sheet was integrated as external shear strengthening for RC beams. Therefore, this study investigated the behavior of simply supported RC beams strengthened externally with anchored CFRP composite using and subjected to combined bending and torsion using Nonlinear Finite Element Analysis (NLFEA). Seventeen models have been constructed and divided into four groups to scrutinize the effect of CFRP anchored depth and CFRP strip spacing. The performance of each beam was evaluated in terms of failure mode, CFRP strain, load-deflection and torsion-twist behavior, ultimate deflection, ultimate load capacity, ultimate angle of twist, ultimate torsion capacity, elastic stiffness, and energy absorption. The enhancement percentage increased with the increase of anchored depth and decreased with the increase of CFRP strip spacing. Finally, the external strengthening with anchored had a superior effect on the ultimate load, ultimate deflection, angle of twist, torsion elastic stiffness, energy absorption.