Study On The Flexural Behavior Of Basalt Fiber Reinforced Fiber Reinforced Concrete Beams

Compared with the reinforced concrete structure,the BFRP bar in the BFRP bar concrete structure has the advantages of greater ultimate tensile strength and good corrosion resistance,and the BFRP bar concrete structure can be used in a variety of harsh environments,and its own weight is also lighter;in BFRP The addition of steel fiber to the reinforced concrete structure can not only reduce the deformation of the component such as the deflection and crack width,but also improve the ultimate bearing capacity.In order to better apply the structure to actual projects,it is necessary to study the bending performance of BFRP steel fiber reinforced concrete beams.This thesis mainly completed the experimental research on the bending performance of 10 BFRP steel fiber reinforced concrete beams,focusing on the analysis of the reinforcement ratio,the volume ratio of steel fiber,the type of reinforcement and the number of steel meshes on the beam,the main research content and conclusions as follows:(1)Combining the load-deflection curve and the recorded value of the load when cracking during the test,the cracking moment of the BFRP steel fiber reinforced concrete beam is analyzed,and the concrete tensile strength and the plastic deformation development capacity of the tension zone are both affected.It depends on the size of the cracking bending moment,not a single decision.The plastic development degree coefficient of the tension zone is put forward,and its size can be used as a criterion for judging the plastic deformation of the component,and combined with the test value,the plastic influence coefficient of the section resistance moment is calculated.(2)With the increase of the reinforcement ratio,the volume ratio of steel fiber and the increase of the number of steel wire meshes,the ultimate bearing capacity of BFRP steel fiber reinforced concrete beams has been improved to varying degrees.Tests have shown that the best blending The volume ratio of steel fiber is 1.5%.Compared with BFRP reinforced concrete beam,the ultimate bearing capacity is increased by 33.6%.According to different failure forms,considering the tensile strength of the steel fiber concrete in the tension zone,the corresponding calculation formula for the flexural bearing capacity of the steel fiber reinforced concrete beam with BFRP reinforcement is proposed.The analysis and comparison of the ultimate bearing capacity and the limit reinforcement ratio of domestic and foreign codes have underestimated the ultimate bearing capacity of BFRP steel fiber reinforced concrete beams,and the limit reinforcement ratio is unsafe.(3)Combined with the analysis of the load-deflection curve and the normal service load,the incorporation of steel fiber can increase the normal service load of the BFRP steel fiber reinforced concrete beam and reduce the deformation of the structure.Under the same load,the larger the volume rate of the steel fiber,the smaller the deflection.Considering the tensile strength of the steel fiber concrete in the tension zone and the large deformation of the BFRP bar,combined with the stiffness analysis method and the effective moment of inertia,the longitudinal direction between the cracks in the tension zone is corrected.Regarding the strain non-uniformity coefficient and effective moment of inertia of FRP bars under tension,the formulas for calculating the stiffness of BFRP bars steel fiber reinforced concrete beams were respectively proposed,and compared with domestic and foreign codes to verify their applicability.(4)Combining the domestic and foreign indicators of ductility evaluation,propose a calculation method suitable for the ductility coefficient of BFRP steel fiber reinforced concrete beams and calculate the ductility coefficients of all test beams.The ductility coefficient increases with the increase of the reinforcement ratio.The ductility of the structure is maximum when the volume ratio of steel fiber is 1.5%.