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.
