Numerical Analysis Of Flexural Behaviour Of Concrete Beams With Hybrid FRP-steel Reinforcement

Fiber-reinforced polymer(FRP)has a lot of excellent material properties like high strength to weight ratio,brilliant resistance towards corrosion,high tensile strength.To substitute FRP bars for steel bars is expected to solve the corrosion problem of steel reinforced concrete structures,While FRP is a linear-elastic material,which could result in the brittle failure mode of concrete members.Moreover,the relatively lower elastic modulus and inferior bond behavior of FRP bars than that of steel bars could be related to greater mid-span deflection and wider cracks.So,researchers came up with the idea of hybrid reinforcement of linear-elastic FRP and elastic-plastic steel bars to enhance the flexural behavior of concrete beams.There are a lot of research has been conducted for CFRP and GFRP,while not much about AFRP.AFRP bar inherits properties like high strength,high elastic modulus,and high abrasion resistance which make these fibers well suited for Fiber-reinforced polymer(FRP)as internal reinforcement in concrete structures.Based on the finite element simulation,this research investigated the flexural behavior of concrete beams with the hybrid reinforcement of AFRP bars and steel bars.The failure mode and load-carrying capacity was analyzed.The main research contents are:(1)The numerical models of concrete beams with hybrid FRP-steel reinforcement was developed based on the geometrical and material properties of reported experimental research conducted by other researchers.The model was able to predict the capacity and the load mid-span deflection relationship of tested beams with accuracy.(2)Based on the finite elements models,the effect of concrete strength,material type of bottom longitudinal bars,size of bottom longitudinal bars and reinforcement ratio on the flextural behavior of concrete beams were investigated.(3)Three failure modes of concrete beams with hybrid FRP-steel reinforcement was analyzed and differentiated,depending on the failure of reinforcement and concrete at the ultimate limit state.The reinforcement ratios dividing the failure modes were proposed.