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Bonding steel plates or FRP laminates to the tension faces of reinforced concrete beams are among the common strengthening methods. Among these two strengthening materials, FRP generally is not capable of fulfilling the ductility demand while fulfilling the high strength demand. Mild steel, on the other hand, is capable of fulfilling both the strength and the ductility demands. However, the use of thick plates, whose application is impractical, might be needed in the case of high strength demand. In the present study, the effects of the composite use of the two materials to overcome the shortcomings of the individual use of each material on the behavior of reinforced concrete beams was investigated. For this purpose, a total of 11 reinforced concrete beams, including a plain beam, two reference beams strengthened with only FRP laminates and 8 beams strengthened with both steel plates and FRP laminates, were tested under transverse loading. The number of CFRP and steel layers, the bonding sequence of these layers and the plate thickness were adopted as the parameters of the present study. The composite use of CFRP and steel proved to have significant contributions to the behavior and strength of reinforced concrete beams and the bonding sequence of the layers was found to be the most important parameter influencing the beam behavior. [ABSTRACT FROM AUTHOR]

The companies give advice values for the resin, accelerator and hardener ratio used in the production of composite materials. Different practices and environmental conditions during the manufacturing stages are effective on the mechanical properties of the final product. It is useful to perform some tests before the final production. In this study, the determined values for the matrix structure are 98.5% polyester, 1% hardener and 0.5% accelerator. The compression test specimen dimensions are respectively diameter and height of 50x100 mm. The reinforcement material chopped strand E glass fiber of 6 mm in length has been used starting from 22% to 88% in 11% increments in 7 different amount of volume. The other reinforcement material of quartz particles with the sizes in the range of 0 to 0.125 mm², have been used starting from 5% to 45% in 5% increments up to 9 different amount of volume. The densities of the prepared samples of fiber and particle reinforced composites at the end of the determined standby time of 7 days and the compressive tests have been carried out. As a result of the experiments, the highest compressive strengths obtained of "fiber composite" with 55% amount of volume was 45.190 N/mm and of "the particle quartz composite" with 10% amount of volume was 131.009 N/mm². The lowest densities in these amounts of volume have been obtained respectively, 1.142 g/cm³ in "fiber composite" and 1.351 g/cm³ in "quartz particle composite". [ABSTRACT FROM AUTHOR]

The use of externally bonded fiber-reinforced plastic (FRP) laminates for strengthening of reinforced concrete beams has become effective method. This method has used because of the advantages of FRP materials such as their high strength-to-weight ratio, good corrosion resistance, and versatility in coping with different sectional shapes and corners. Many studies on this theme have been carried out since the early 1900s. In this study, interfacial stresses of reinforced concrete beams strengthened with FRP effect the parameters will be studied as experimental and numerical. Adhesives used in the beams applied to FRP's thickness, adhesive type and the state of the concrete surface, produced experimental samples were exposed to the bending effect will be studied as a comparative. Afterwards, by using the ANSYS® WB finite element program to model and analyze RC beams by externally bonding FRP will be carried out. Adhesive thickness, adhesive type, the concrete surface will be done by entering the parameters for analysis of stress can be obtained as a result. Thus, the analytical expressions of stress and normal stress equations will establish should be modified. Finite element analysis and experimental results will be compared, compatibility is investigated, the results and recommendations presented by the study will be completed. [ABSTRACT FROM AUTHOR]