Flexural Behavior Of Steel Fiber Reinforced High-strength Concrete Beams With FRP Bars Under Repeated Loading

Fiber reinforced polymer bars(FRP bars)as well as steel fiber high-strength concrete with its superior characteristics have become very promising new building materials in the field of Civil Engineering.FRP steel fiber reinforced high-strength concrete beams formed by the combination of FRP bars and steel fiber reinforced high-strength concrete can enhance the bond performance between concrete and rebar,delay cracking and crack extension,increases the stiffness of the structure,which can solve the problem of traditional steel corrosion of reinforced concrete beams from the root,and can effectively solve the existence of cracks of FRP reinforced concrete beams under load is too wide,large deformation and brittle fracture problems.Therefore,the study of FRP steel fiber reinforced high-strength concrete structure is of great significance for improving the safety,applicability and durability of reinforced concrete structure.A total of five test samples,including four BFRP reinforced steel fiber highstrength and steel fiber reinforced high-strength concrete beams.Focus on loading process,failure modes,crack development,hysteretic curves,residual deformation skeleton curves,ductility,stiffness degradation,strength degradation and other properties under repeated loading.Flexural capacity and deformation behavior of high-strength concrete beams reinforced with BFRP bars and steel fiber under repeated load can be significantly improved by increasing FRP reinforcement ratio and the addition of steel fiber.Through the analysis of bending test results and the strain relation of BFRP bars and concrete in the mid-span section of high-strength concrete beams reinforced with BFRP bars and steel fiber under repeated loading.Based on the experimental and theoretical analysis,a calculating method for different failure modes,which can be used for evaluating the flexural capacity of high-strength concrete beams reinforced with FRP bars and steel fiber,was proposed.The calculated values have good agreement with test results.The finite element mode of high-strength concrete beams reinforced with BFRP bars and steel fiber are established by FEM analysis software(ANSYS).Based on the established finite element model and the element,the cracking behavior,the ultimate flexural bearing capacity and the skeleton curve before BFRP bars reaches the nominal yield strength of high-strength concrete beams reinforced with BFRP bars and steel fiber the repeated loading are obtained.The results using FEM analysis is in good agreement with test results.