Research On Bond Behavior Of GFRP Bar And Fiber Reinforced Concrete

In construction,steel reinforced concrete is the most widely used structural material in the world nowadays.However,it is well known that under certain environments corrosion of steel reinforcement can lead to the deterioration or even the collapse of structural elements.Billions of dollars are spent every year worldwide in repairing and strengthening concrete structures whose reinforcement has deteriorated due to corrosion.An option to overcome the above-mentioned problems is the fiber-reinforced polymer(FRP)composite material.The main advantages to use fiber-reinforced polymer composite are high tension strength for a low density,absence of sensitivity to corrosion and a long fatigue life.All these factors offset the high cost of these materials.Although GFRP bars have better mechanical properties than steel bars,the poor synergy between GFRP bars and concrete makes GFRP unable to exert all mechanical properties.The incorporation of fibers into cementitious materials can effectively enhance the crack resistance and toughness of materials,thereby increasing the bond strength between GFRP bars and concrete.The purpose of this paper is to study the bond behavior between GFRP bars and glass fiber reinforced concrete and polypropylene fiber reinforced concrete.Through the comparison experiment with the bond performance of concrete,the bonding performance of concrete and GFRP reinforcement with different kinds of fiber content was observed.In this paper,there are 51 specimens.First,the bond slip behavior of polypropylene fiber reinforced concrete and glass fiber reinforced concrete and GFRP bars is studied by 39 bond slip specimens.The bond-slip properties between fiber-reinforced concrete and GFRP bars with different bond lengths and different fiber contents were studied,and the failure modes of the drawn specimens and the force-bearing process of GFRP bars in the drawing process were analyzed to determine the optimum of the fiber content and proportion of fiber-reinforced concrete,and the bond-slip constitutive model of GFRP bars and fiber-reinforced concrete.Secondly,12 specimens were used to study the distribution of bond stress between polypropylene fiber reinforced concrete and glass fiber reinforced concrete and GFRP bar along the surface of the GFRP bar.A strain gauge is placed on the surface of the reinforcing bar to measure the strain at each measuring point in the drawing process.Then,through the measured strain,we can get the bond stress between the measured points and the concrete under different loads.According to the different load levels,the corresponding curves are made to find the trend of the distribution of the bond stress on the surface of the rib with the increase of load during the loading process.As the two fibers used in this paper have good economy,polypropylene fiber can significantly improve the bonding performance of GFRP bars and concrete,which has the characteristics of being inexpensive and inexpensive.Through the research and analysis in this paper,the future research on the bonding properties of GFRP bars and fiber reinforced concrete will be provided a basis for future practical engineering.