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Abstract
The use of fiber reinforcement polymers (FRP) bars to reinforce concrete elements instead of the conventional steel bars is becoming more and more popular all over the world.
Glass fiber rebars (GFRP) is one of the FRP which have many advantages such as higher strength to weight, higher resistance to corrosion as well as higher resistance to fatigue loads. One of the main disadvantages of GFRP bars is its lack of ductility. The linearly behavior of the GFRP bars up to failure make their application incomparable with conventional steel bars. One solution to provide ductility is a hybrid FRP reinforced bars. The proposed hybrid rebar consists of different types of fibers which fail at different strains during the loading of the rebar, by allowing a gradual failure of the rebar. This sort of hybrid rebars is not yet popular in Egypt in spite of the high need for it, especially in structures exposed to corrosion.
This thesis presents a research program that includes a pilot trial to manufacture locally HFRP rebars using the Pultrusion method using two different types of fiber, Carbon and Aramid, with 3 different replacement ratios of Glass fiber in the volume fraction for each to improve the behavior of GFRP bars, especially its brittle sudden failure.
Twenty one rebars have been manufactured; the manufacturing of rebars process and the preliminary testing of rebars (tensile strength, stiffness, unit weight and fiber volume fraction) are described. The application of the new reinforcement rebars in concrete beams is also presented and tested in flexure. The experimental program includes 9 tested beams to examine several variables such as the effect of number of anchorage to improve the bond between GFRP bars and concrete and its effect on the beam failure behavior. The effect of different manufactured rebars on the ultimate load, strain, and deflection of beam and the semi ductile behavior of the HFRP rebars are also presented. The experimental program also include a control beam reinforced with conventional steel reinforcement bars.
Finally, conclusions were summarized and recommendations were stated for future work.