Bending and bond behavior and design of concrete beams reinforced with fiber-reinforced plastic rebars

The use of non-corrosive fiber reinforced plastic (FRP) rebars in lieu of mild steel rods is investigated. The present work cover experimental testing of twenty seven concrete beams reinforced with FRP rebars subjected to bending , twenty four cantilever specimens subjected to bond forces, and twelve straight pull-out specimens. The following response of concrete beams reinforced with FRP rebars were investigated: preand post-cracking behavior, load-deflection and stress variations, elastic and ultimate load carrying capacities, crack widths and patterns, bond stress and embedment length, and modes of failure. In order to take advantage of the high tensile strength of FRP rebars (80 to 130 ksi), high strength (610 ksi) concrete in lieu of regular strength concrete ( 4 ksi) is used. The use of sand coated FRP rebars in addition to high strength concretes improved the overall behavior of the beams. It is shown that a 90% increase in ultimate moment capacity is achieved over beams reinforced with steel rebars for the same area and strength of concrete. Theoretical correlations with experimental results are conducted in terms of elastic and ultimate bending moment, crack width, post cracking deflection, and bond and development length. Simple design equations for structural design applications are developed with similarities and parallels to current ACI 318-89 code equations. A step by step design example is presented based on the above design equations.