STRENGTHENING AND REPAIRING OF RC DEEP BEAMS USING CFRP AND GFRP

There are many reasons to upgrade an existing structure such as building code changes, accidents, design errors or building use changes. Few years ago the construction industry began using fibre reinforced polymer (FRP) for structural reinforcement, typically in combination with other building materials such as wood, steel and concrete. FRP show multiple attractive properties, such as low weight to strength ratio, non-corrosiveness high fatigue strength, and case of application. This study investigated different techniques to improve the performance of RC deep beams under two concentrated vertical loads using advanced composite materials (CFRP and GFRP sheets). The primary aim of this research was to study the behaviour of deep beams strengthened and repaired in shear using carbon and glass fibres. Thirteen RC deep beam specimens were simply supported with span lengths L=1500 mm and cross sections 140 x 450 mm. The tested beams were subjected to the effects of two concentrated loads with spacing of 560, 360 and 160 mm and were divided into five groups. The test results show that the deep beams strengthened by CFRP sheets & GFRP sheets provided improvement in ultimate loads. The maximum increase in ultimate loads reached 106% & 81% respectively and the decrease in deflection for beams was attributed to the type, configurations and orientation of the FRP sheets. An analytical model was done based on code equations to predict the deformational behaviour of RC deep beams shear-strengthened with FRP composites , and obtain the failure loads by using three codes equations and compare the results with the experimental results ,The proposed analytical model gave good compliance with theexperimental results .