Experimental Studies And FEM Analysis Of Concrete Beams Reinforced With FRP Bars

Over the last decade, fiber reinforced polymer (FRP) bars have emerged as one of the most promising solutions to the corrosion problems of steel reinforcement in structural concrete. FRP bar is a composite material, which is composed of fiber acting as reinforced material, synthetic resin acting as matrix, and some adequate auxiliaries, and is formed through a pultrusion process and necessary surface treatment. It has a high strength to density ratio, excellent corrosion resistance, high fatigue, strong design ability and magnetic neutrality, so it can be used in the applications with special performance requirements or where reinforcing bars are subjected to severe chemical attack. For example, FRP reinforced concrete is used to support or surround magnetic resonance imaging (MRI) medical equipment, and FRP is also used for the constructions of some seawalls, industrial roof decks, base pads for electrical and reactor equipment, anchor in rock and ground engineering and concrete floor slabs in aggressive chemical environments. However, some disadvantages such as the low elastic modulus, liner elastic stress-strain relationship, weak lateral shear strength, and different adhesive property between FRP bar and concrete, which produce much unlikeness in structural performance between conventional reinforced concrete members and concrete members reinforced with FRP bars, so calculation and design methods applicable to the former are inapplicable to the latter, and needing further study.Based on the mechanical property test of FRP bars and the experiment studies of FRP reinforced concrete beams under vertical loads, the mechanical property indexes for structural design of FRP bar were proposed and the design method for FRP bar concrete beam were explored in this paper. Major research contents and contributions are as follows:1. Research on mechanical property of FRP bars.The mechanical property test method on tensile strength, elastic modulus and rate of elongation, etc. of FRP bar was researched. The statistical tensile test results are analyzed, based on that the mechanical property index for structural design of FRP bar are put forward. 2. Experimental research on flexural behavior for FRP bar concrete beam.Seven FRP bar concrete beams were tested under vertical loads at three-dividing point, measuring the deflection, crack width and section strain. Based on the test results, the cracking pattern, load-deflection history and section strain history were plotted. The influencing factors such as the type of FRP bar, the reinforcement ratio and the adhesive bonding action with concrete, etc. to loading capacity and deformability of members in bending were researched.3. Non-liner finite element analysis of FRP bar concrete beam.Using commercial finite element software, ANSYS, finite element simulation of FRP bar concrete beams is accomplished. It is modeling method, selecting element, defining constitutive relationship of materials and solution method that are elaborated on in this paper, and the reliability of the finite element model is testified by compared with experiment results. The influencing factors to the deformation of FRP bar concrete beam including reinforcement ratio, the type of FRP bar, the strength of concrete, sectional dimension and the type of load are analyzed using the finite element model as mentioned above.4. Research on calculation and design method of FRP bar concrete beamAccording to the experiment results, simulation results and the up-to-date analytical methods for reinforced concrete and in cooperation with loading procedure, failure mode, crack pattern and the deformation characteristics, etc, researching the flexural calculation methods for loading capacity and the calculation methods for maximum crack width and deflection of FRP bar concrete beam. The theoretical calculation and design system of the flexural performance of concrete beams reinforced with FRP bar is established systematically.