Strengthening of reinforced concrete beams using innovative ductile composite fiber-reinforced polymer systems.

Although the technique of external strengthening of reinforced concrete beams using externally bonded Fiber Reinforced Polymer (FRP) materials has been established as an effective tool for rehabilitating and strengthening reinforced concrete beams, it is still suffering from some drawbacks. A significant part of these drawbacks is attributed to the characteristics of currently available FRP strengthening systems. This study deals with the development and evaluation of the effectiveness of two innovative ductile FRP systems for flexural/shear strengthening of reinforced concrete beams. The systems are fabrics that are hybrid of glass and carbon fibers and designed to have the potential to avoid most of the drawbacks experienced by currently available FRP strengthening systems. The new systems are unique as they can provide yield plateaus similar to that provided by steel in tension. The ideal characteristics of a strengthening material for both flexure and shear were investigated. A parametric study was conducted on the loading behavior of triaxially braided fabrics. Based on these investigations, the systems were designed and manufactured. An experimental investigation was conducted to evaluate the behavior of reinforced concrete beams strengthened in flexure/shear using the new systems. Reinforced concrete simple and continuous beams were strengthened in flexural/shear using the new systems applying different strengthening schemes. Identical beams were strengthened using some commercially available carbon fiber sheets, fabrics, and plates, as well as steel plates, in order to compare their behavior with those strengthened with the developed systems. The beams were loaded until failure and their responses were investigated for ductility, FRP exploitability, and failure modes. The beams strengthened in flexure with the new systems exhibited greater ductility than those strengthened with the carbon fiber strengthening systems and produced yield plateaus similar to those of the unstrengthened beams and also to those strengthened using steel plates. The test results showed that the strengths of the new systems were fully exploited. Guidelines for the design of the developed systems for flexural and shear strengthening of reinforced concrete beams were presented. Numerical examples of reinforced concrete beams strengthened in flexure or shear were also presented in order to clarify the design procedures.Dept. of Civil and Environmental Engineering. Paper copy at Leddy Library: Theses & Major Papers - Basement, West Bldg. / Call Number: Thesis2003 .R34. Source: Dissertation Abstracts International, Volume: 64-10, Section: B, page: 5103. Adviser: George Abdel-Sayed. Thesis (Ph.D.)--University of Windsor (Canada), 2003