Proceedings of the 4 th World Congress on Civil, Structural, and Environmental Engineering (CSEE’19) Rome, Italy – April, 2019 Paper No. ICSECT 153 DOI: 10.11159/icsect19.153 ICSECT 153-1 Predicting Flexural Capacity of Concrete Beams Reinforced with GFRP Bars and Strengthened with CFRP Sheets M. Talha Junaid 1 , Abdalla Elbana 1 , Salah Altoubat 1 1 Department of Civil and Environmental Engineering, University of Sharjah United Arab Emirates mjunaid@sharjah.ac.ae; U00045867@sharjah.ac.ae; saltoubat@sharjah.ac.ae Abstract - FRP material has proven to be a proper replacement for the traditional steel reinforcement having superior mechanical properties and high tensile strength. FRP is a highly durable material being nonmagnetic and noncorrosive material. Such materials are effectively used as a construction material that is specially situated in an aggressive environment. This paper investigates the performance of concrete beams reinforced with glass fiber reinforced polymer bars (GFRP) and the applicability of carbon fiber reinforced polymer (CFRP) sheets as a strengthening regime for such systems. With this intent, a total of four 2.4m RC beams were tested. All beams were reinforced with GFRP bars in flexure and shear. Two served as reference beams, and the remaining two were strengthened with CFRP wrap fabric. It was found that the contribution of GFRP bars in load carrying capacity for beams strengthened by CFRP sheet is not as efficient as when CFRP is used with steel rebars. This could be attributed to the difference in stress-strain relationship of the GFRP, CFRP, and steel which are distinctly different from each other. While CFRP and steel have similar modulus values, the modulus value for GFRP is substantially low. Finally, a contribution factor ( ) for predicting the flexural capacity for such systems as per ACI 440 proposal. Keywords: Glass fiber reinforced polymer, flexural capacity, carbon fiber reinforced polymer, stress-strain; strengthening. 1. Introduction Conventional steel reinforcement has long been used to provide tensile strength to conventional concrete. However, these are prone to corrosion thus leading to non-durable concrete structures [1]. Recently, fiber-reinforced polymer (FRP) reinforcement bars made of polymer matrices reinforced with glass, carbon, or basalt fibers have become an alternative to the traditional steel reinforcement for concrete [2-4]. FRP has superior durability properties being a nonmagnetic and a noncorrosive material. FRP reinforcement exhibit superior mechanical properties, such as high tensile strength and low self- weight, which make it suitable for concrete structures [5-7]. On the other hand, externally bonded fiber reinforced polymers (FRP) are used for strengthening or repairing of existing concrete members to improve load-resistance as well as serviceability [8]. The fibers are used to create composite sheets which are bonded together by resin. FRP materials are used for strengthening in several forms depending on the application including the flexural and shear strengthening of beams, slabs, columns, and walls. The fibers may be made of carbon, aramid, or glass. Carbon FRP is widely used for strengthening owing to very low creep and high strength and is the most brittle fiber among others. Although the use of Carbon FRP sheets for the strengthening of conventional steel flexural members is widely reported [9-12], the use of glass fiber reinforced polymer bars in flexural members and strengthened with Carbon FRP sheets has not been reported in open literature. This work, therefore, looks at the behavior of the flexural behavior of concrete beams reinforced with GFRP rebars and strengthened with CFRP sheets. The contribution of the reinforcement and strengthening system on the load carrying capacity of such systems is also studied. 2. Materials and Methods Ordinary Portland cement-based concrete with average compressive strength and modulus of rupture of 41 MPa and 4.05MPa, respectively. Straight GFRP bars without anchor head with a deformed surface under the product name MateenBar provided by Pultron Composites UAE were used in this study. The nominal diameters used were 16 mm for flexural reinforcement (f * fu = 690 MPa  * fu= 0.0135 and Ef = 51 ±2.5) and bar size of 10 mm was used for shear reinforcement. All beams were equipped with two 10 mm bars in the compression zone. Four beams, each 2.4m long with a simply supported