INVESTIGATION ON STRENGTHENING OF REINFORCED CONCRETE BEAMS WITH GFRP COMPOSITES MODIFIED BY SILANE AGENT

Concrete structures are known as reliable structures, but some construction errors and construction negligence can lead to defects in these structures. The defects can be due to poor design practices, poor quality control, or poor structural design and detailing. In recent years, various strengthening methods, including the use of polymer composites, have gained much attention to resolve the defects, especially for the flexural elements. Glass fiber-reinforced polymers (GFRPs), as a common type of composite materials, comprise two components, namely the matrix and fibers. This paper investigates the effects of the silane surface modifier on the resistance of GFRP and the capacity of the reinforced concrete beams. For this purpose, the silanemodifying agent of 3-aminopropyltriethoxysilane (APTES) with an adequate weight percentage is used as a modifier, and the composite samples are fabricated and tested with and without the surface modifier. The results of the experimental studies are used in numerical studies. The capacity of beams strengthened with the GFRP composites (including composites with modifier and composite without a modifier) is determined using finite element analysis and compared with the capacity of a beam without strengthening. Numerical analysis results indicate that the use of GFRP composite without the silane surface modifier increases the capacity of the beam by approximately 15%. On the other hand, the use of GFRP composite with silane surface modifier increases the capacity of the selected beam by about 28%.