NUMERICAL INVESTIGATION ON THE SHEAR BEHAVIOUR OF CARBON FIBER REINFORCED POLYMERS SHEETS STRENGTHENED RECYCLED AGGREGATE REINFORCED CONCRETE BEAMS WITH RECTANGULAR OPENINGS NEAR SUPPORT

Abstract

The increasing demand for sustainable construction materials has prompted a shift towards recycled aggregates in concrete production, offering environmental benefits and natural aggregate resource conservation. However, the incorporation of recycled aggregates poses challenges in mechanical properties, especially in shear-sensitive elements like beams. In order to increase the shear capacity of recycled aggregate concrete (RAC) beams—which is important in situations where rectangular holes are necessary for utilities and other critical services—carbon fiber reinforced polymer (CFRP) strengthening techniques are investigated. This study employs finite element analysis (FEA) to replicate the behavior of RAC beams with rectangular holes that have been strengthened with CFRP under static loading circumstances. Validation against experimental data ensures model accuracy. The effects of key parameters such as opening size and location, CFRP layering, and recycled aggregate replacement ratios on the shear behavior are systematically investigated. The finite element analysis (FEA) was compared to a control beam; the shear capacity of RC beams was found to be reduced by up to 32.23% when significant apertures were added. Results reveal that CFRP strengthening improves shear capacity by 21% to 31%, with beams exhibiting 90% to 95% of the failure load of solid counterparts for specified opening sizes. Additionally, reducing recycled aggregate content from 100% to 30% increases load resistance by 25%. Furthermore, the influence of various parameters on the shear response, including failure modes, load-deflection behavior and load strain curves are analyzed and discussed. These findings contribute valuable insights into enhancing the structural performance of sustainable concrete elements, guiding design and retrofitting strategies for RAC structures subject to shear loading and openings.