STRENGTHENING OF SHEAR DEFICIENT REINFORCED CONCRETE BEAMS USING NEAR SURFACE EMBEDDED FABRIC REINFORCED CEMENTITIOUS MATRIX

Abstract

This thesis presents an experimental study on the efficacy of new concepts of strengthening reinforced concrete beams deficient in shear. The first concept is referred to as “near surface embedded” fabric reinforced cementitious matrix (NSE-FRCM). The interaction between the transverse shear reinforcement (TSR) and NSE-FRCM system has been investigated. The second concept, which is a combination of the NSE-FRCM and externally bonded FRCM is also investigated and can also be referred to as hybrid “near surface embedded/ externally bonded” NSE/EB-FRCM system. The experimental program included construction and testing of twenty medium-scaled RC beams. Two beams were kept unstrengthened to act as references, while twelve beams were strengthened using the NSE-FRCM technique and the remaining six beams were strengthened using the hybrid NSE/EB-FRCM. For the NSE-FRCM technique, six beams were reinforced in shear with 6 mm diameter steel bars spaced at 215 mm within the critical shear span (CSS), while the remaining six beams had no TSR. The test variables included the FRCM type (carbon FRCM, glass FRCM and polyparaphenylene benzobisoxazole FRCM), strengthening configuration (full and intermittent strips), and presence of TSR within the CSS (for the NSE-FRCM technique). The test results revealed that both NSE-FRCM and hybrid NSE/EB-FRCM techniques can be used to significantly enhance the shear behavior of RC beams. Moreover, the NSE-FRCM system has shown to be a promising alternative to the conventional externally bonded FRCM system with the advantage of reducing the tendency to debonding of FRCM off the concrete substrate. Finally, an analytical approach has been proposed based on the simplified compression field theory (SCFT) to predict the ultimate load carrying capacity of RC beams strengthened in shear using FRCM system. A database of over sixty RC beams strengthened in shear using different FRCM fabric types, obtained from the literature, has been used to validate the proposed model.