The search for a non-corrosion alternative for steel reinforcement expands daily, especially in construction exposed to chemical attacks such as carbonation in aggressive environmental conditions. Glass Fiber Reinforced Polymer (GFRP) bars have become a pioneer in alternatives because of its many advantages such as high tensile strength, lightweight and corrosion-resistant characteristics. In this research, the cracking loads, ultimate loads, crack propagation behavior, load-deflection curves, and the damage to beams were observed at the failure stage for high strength concrete beams (HSCBs) reinforced with GFRP bars through finite element analysis (FEA). A three-dimensional, finite element model of a reinforced HSCB was proposed using non-linear finite elements software. The proposed model considers the impact of cracks in concrete and includes the details of longitudinal as well as transverse reinforcement. The proposed analytical model was verified experimentally through an experimental study conducted for three simply supported beam specimens. The first specimen was reinforced in flexure with steel bars; the second specimen was reinforced with GFRP bars, and the third specimen was reinforced with GFRP bars in addition to steel fibers with volume of 1.0%. A close agreement between the experimental results and the corresponding analytical results was obtained. Then, the verified model was used to study the effect of the change in the compressive strength of concrete and the ratio of longitudinal GFRP bars on the behavior of the reinforced concrete beams. The behavior in GFRP-reinforced concrete beams was different with the change of concrete strength and GFRP ratio when subjected to a given load, where when using a GFRP ratio up to 0.5% with HSC equal to or more than 60 MPa, the rupture of the GFRP bars occurred before crushing in the concrete; Also, it was noted that the replacement of steel reinforcement with GFRP bars accelerates the appearance of the initial cracks and increases the failure load in HSCBs, where the first crack in the beams reinforced with, GFRP bars, GFRP bars and containing 1.0 % of steel fiber , and steel bars were 22.5 kN, 29 kN, and 42 kN respectively. The vertical stiffness for the HSCBs reinforced with steel bars reached BEHAVIOR OF HIGH STRENGTH CONCRETE BEAMS REINFORCED WITH (GFRP) BARS 1057 JAUES,16,61,2021 about 3.5 times and 2.6 times from the stiffness of the HSCBs reinforced with GFRP bars and the HSCBs containing 1.0 % of steel fiber reinforced with GFRP bars respectively.

In the present investigation, the behavior of ultra-high strength concrete (UHSC) beams containing different reinforcement ratio and stirrups was investigated. The concrete was successfully prepared from Egyptian local materials. Series of cubes and cylinders were prepared to examine the compressive and splitting strengths of the UHSC at different ages. Eight reinforced beams have been prepared and tested at 28 days. The outcomes indicated that the compressive strength ratio between cylinders and cubes samples are 90%, 87% and 85% at 7,28, and 56 days respectively, while the ratio between tensile strength to compressive strength is 38.5% and 36.6% at 7 and 28 days respectively. Furthermore, the beams test outcomes were presented and discussed as deflection, ultimate loads, cracking, failure modes and ductility.