Shear and flexural behaviour of reinforced concrete beam externally strengthened with fiber reinforced polymer (FRP) / Syed Hazni Abd Gani

The utilisation and application of natural fiber based Fibre Reinforced Polymer (FRP) as strengthening material is still rare. In addition, the repairing and strengthening method needs improvement to enhance the performance of structural strengthening. The potential of natural fibers based FRP as strengthening materials was explored in the present study and its performance was compared with those of synthetic based FRP. The performance was measured in terms of shear and flexural strength of strengthened reinforced concrete (RC) beam with respect to various of shear span distance and length of FRP plates and bars. Carbon Fiber Reinforced Polymer (CFRP), Glass Fiber Reinforced Polymer (GFRP) and Kenaf Fiber Reinforced Polymer (KenFRP) were used as strengthening materials. Two (2) techniques of strengthening namely External Bonded Plate (EBP) and Near Surface Mounted (NSM) were adopted. For EBP method, twenty four (24) RC beam specimens with the size 250 mm x 400 mm x 3000 mm were fabricated. It was a flexural strengthening but tested in shear with FRP plate size of 100 mm x 1.2 mm x 2700 mm that was glued on the tension surface of the beam specimens. Two (2) variables were investigated which are types of FRP and various shear span distance which are 300 mm, 220 mm and 100 mm. For the NSM method, twenty (20) RC beams with the size same as these strengthened with EBP method were fabricated. The beam specimens flexural strengthened with 8 mm diameter of bar and the bar was glued at groove of the beam soffit. Two (2) variables were investigated between type of FRPs and various length of FRP bar which are 1250 mm, 1750 mm and 2500 mm length. The four point bending test was adopted. The load-deflection curve was distinguished in order to determine the behaviour both of the beam specimens strengthened using two (2) methods namely EBP and NSM. The crack propagation and the effectiveness of using various FRP either synthetic or natural fiber corresponding to variables adopted were also assessed. Thus, whether natural fiber based FRP could behave equally good as other synthetic fiber based FRP as strengthening material could be established.