Flexural behavior of self-compacting damaged reinforced concrete box beams strengthening with CFRP

Abstract

Fibre Reinforced Polymer (FRP) materials appear to offer an acceptable solution for the upgrading and repair of concrete structures based on the advantages associated with these compounds. This paper presents an experimental analysis of strengthening in damaged R.C. box beams based on gluing CFRP sheets to the members. The main objective was to study the flexural behaviours of damaged R.C. box beams strengthened with CFRP sheets, and ten simply supported box beam specimens were thus tested under a monotonic two-line load. Variables investigated included the configuration of CFRP sheets used and the damage ratios (45%, 60%, and 75%). The tested box beams were designed according to ACI 318M-14 to ensure flexural failure. The study showed that adding composite fibre sheets used as External Bonding (EB) technology can offer a convenient and effective strengthening method for damaged concrete structures. The results further showed that side strengthening (extending the sheet under the beam with both sides facing each other) provided an effective tool for increasing the ultimate load capacity by over 28% on average as compared to other methods, while increasing the deflection ratio by over 40%. The behaviour of each box beam was examined with respect to the first crack load, ultimate load, crack pattern, and load-deflection, and carbon fabrics were shown play a major role in the repair of box beams.