Flexural Behavior Of Steel Fiber-Reinforced Concrete Beams Reinforced With BFRP Bars Eroded By Seawater Under Repeated Loading

The vast sea area of China contains abundant natural resources,and marine development has become one of our important strategic objectives.However,the durability of reinforced concrete structures in the marine environment.has become increasingly prominent.Based on the characteristics of linear elasticity,light weight and high strength,corrosion resistance of FRP bars and high compressive and tensile strength,strong deformation resistance,good toughness and excellent corrosion resistance of steel fiber reinforced high-strength concrete,the FRP bars are combined with steel fiber reinforced high-strength concrete to form steel fiber-reinforced high-strength concrete beams reinforced with BFRP bars to improve the bonding performance and reduce the bond damage between FRP bars and concrete under repeated loading,increase the cross-section stiffness,and improve the bearing capacity and ductility of FRP bars reinforced concrete structures.The application of steel fiber-reinforced high-strength concrete beams reinforced with BFRP bars in the marine environment can not only fundamentally solve the problem of steel corrosion in traditional reinforced concrete structures,but also improve the mechanical properties of structures and enhance the safety,applicability and durability of concrete structures.In this paper,eight test beams(7 of them are steel fiber-reinforced high-strength concrete beams reinforced with BFRP bars and 1 of them is steel fiber reinforced high-strength concrete beams)are applied to study the effects of reinforcement ratio,damage degree and types of reinforcement on the failure modes,crack development,hysteresis curves,residual deformation,skeleton curves,ductility,stiffness degradation and strength attenuation of steel fiber-reinforced high-strength concrete beams reinforced with BFRP bars eroded by simulated seawater solution under repeated loading.The results indicate that the ultimate tensile strength and modulus of elasticity of BFRP tendons are reduced by seawater erosion.Under repeated loading,the failuremodes of the specimens are all BFRP bar rupture.Increasing the reinforcement ratio of FRP bars properly can increase the ultimate bearing capacity and section stiffness of specimens,delay the cracking of specimens and improve the ductility of specimens;however,the degree of damage has obvious adverse effects on the flexural performance of specimens.The higher the degree of damage is,the weaker the crack resistance of steel fibers,the worse the ultimate bearing capacity,section stiffness and ductility of specimens will be.Steel fiber-reinforced high-strength concrete beams reinforced with BFRP bars eroded by sea water show better applicability and durability under repeated loading compared with steel fiber-reinforced high-strength concrete beams reinforced with steel bars.Based on the test results,the calculation model of flexural capacity of Steel fiber-reinforced high-strength concrete beams reinforced with BFRP bars eroded by sea water under repeated loading is established,and the calculation method is proposed.