Experimental Investigation on Flexural Behaviour of RC Beams Strengthened with Various FRP Composite Configurations

Abstract

AbstractStrengthening the reinforced concrete (RC) beams in buildings and bridges is often needed to improve flexural performance. The various reasons for strengthening are (i) defective design or construction, (ii) deterioration due to the extreme weather conditions, (iii) to carry the additional storage or vehicular loading requirements, (iv) updating to the new code requirements, and (v) seismic strengthening and retrofitting. The fibre reinforced polymer (FRP) strengthening is proven to be very practical and advantageous compared to conventional methods like concrete jacketing and steel jacketing. The available literature mainly focuses on the flexural strengthening of RC beams with external bonding (EB) of pultruded laminates and is limited to laboratory scale specimens. Understanding the flexural behaviour of large-scale specimens consisting of various strengthening configurations is essential. In this study, an experimental investigation is carried out by testing RC beams of 300 × 300 × 3500 mm size. The test matrix consists of RC control beam; three other beams strengthened with CFRP precured laminates (EB-L), CFRP fabric (EB-F) and hybrid FRP strengthening (HYB). The hybrid FRP strengthening is the combination of CFRP pre-cured laminates at the soffit and EB CFRP fabric in the overall length of the beam. All the FRP strengthened specimens had improved flexural strength. However, HYB FRP strengthening was found to be very effective in enhancing flexural strength and ductility compared to other strengthening techniques. In HYB strengthening, the EB confinement provided by the CFRP fabric improves the compression strength of the concrete at the compression zone and prevents the debonding of CFRP laminates at the tension zone.KeywordsRC beamCFRP laminatesCFRP fabricHYB FRP strengtheningFlexural loading