Study On Flexural Behavior Of Concrete Beam Of Circular Section Reinforced With GFRP Bars

GFRP has a series of properties such as light weight, high strength, resistance toerosion, fatigue or electro-magnetic radiation, which can be made into GFRP barswith special technique, can replace steel bars in concrete structures. However, as atype of elastic material, its sudden rupture without any yielding point or plasticproperty in the ultimate stage of tension will cause the unexpected failure of flexuralmembers. It is of great importance to study mechanical property of GFRP bars aswell as the flexural property and failure mechanism of GFRP-reinforced concretebeams.In this paper, the basic mechanical properties of GFRP bars and the influencefactors of bonding performance between GFRP bars and concrete are studied, baseon the results of it, the calculation formulas of flexural capacity for GFRP-reinforced concrete beams has be derived. The relevant experimental data ofGFRP-reinforced concrete beams and analysis of ANSYS all verify the rationalityof the formula. Besides, ANSYS analyse the key parameters which affectingdeformation performance. The Paper’s major results are as follows:(1)The mechanical property of GFRP bars of eighteen different diameter areexperimentally investigated, turned out that the stress-strain relationship is a linearand the tensile strength is great high. But the tensile strength and shear strengthdecreases with the increase of diameter and the elasticity modulus is about40Gpa.(2)The bonding strength experiment between GFRP and concrete indicate thatparameters of thread on the bars have a great influence on the bonding property. Inorder to ensure the bonding reliability, the paper suggest that the depth of threadshould be1.0~1.2mm and the pitch should be0.8~1d.Besides, blasting treatment isnecessary.(3)The paper suggest the compressive failure modes and the relative centralangle of the compression zone under critical condition, base on the current standard.And then the flexural capacity’s formulas for GFRP-reinforced concrete beams hasbe derived. It proved more reasonable than the standard’s.(4)The bending test indicate that the loading process of GFRP-reinforcedconcrete beams is constitutes by the elastic stage, the flat roof stage and the steadygrowth. The test verify the assumption of plane cross section and the formulas.Besides, it show that increasing reinforcement ratios has a bigger effect oncrack width than cracking load. (5)The numerical simulation results by ANSYS are well agree withexperimental results. According the results,deflection is greatly affected bytensile stiffness and reinforcement ratios. The deflection and bearing capacity of thebeam with GFRP bars is larger than it with rebar. Various factors should beconsidered to limit deformation and meet the require in design.