Study On Shear Behavior Of Concrete Beams Reinforced With Steel-fiber Composite Bar(SFCB)

In the process of civil engineering construction,reinforced concrete structure occupies the core position,but the shortcomings of steel corrosion lead to the durability problem of this traditional structure is increasingly prominent,especially in some bad conditions.In recent years,a large number of domestic and foreign scholars have done a lot of experimental research on the fiber reinforced polymer(FRP),which has the advantages of high strength,light specific gravity,fatigue resistance,corrosion resistance and so on.This new material has a good application prospect.However,in the research,it is found that the elastic modulus of FRP bars are low,the plastic deformation ability is poor and anisotropic,and it is easy to brittle failure in shear;the ductility of FRP bars is small,there is no yield stage,and there is no obvious omen of structural failure.At the same time,the cost of FRP materials is expensive,and the cost of building with full FRP structure is higher.Steel-fiber composite bar(SFCB)is a new type of steel bar,which is composed of inner core steel bar and outer longitudinal FRP bar.It has high ductility of steel and high strength of FRP bar.SFCB not only has high tensile strength,high modulus,but also has good corrosion resistance.As a coating,it also brings good corrosion resistance to the steel bar.It has stable and reliable "secondary stiffness" and excellent ductility and energy dissipation capacity in the structure.It has the advantages of small residual displacement after earthquake and easy repair.At present,some scholars have carried out experimental research on the bending resistance of SFCB concrete beams,but the research on the shear resistance of SFCB structure is less.It is necessary to fully understand the shear resistance of SFCB in practical engineering in the future.In this paper,steel-fiber composite bars are selected as test materials.Through the experimental comparison between B-SFCB beam and ordinary reinforced concrete beam and BFRP reinforced concrete beam,the influencing factors and mechanical laws of B-SFCB beam under load are analyzed.Based on the comparison of the test results of shear failure forms,ultimate bearing capacity,longitudinal strain,crack development and mid span displacement of various beams,the shear behavior of steel continuous basalt fiber reinforced concrete beams under concentrated load is analyzed.By comparing the shear calculation formulas of FRP reinforced concrete beams in different countries and combining with the test results,the influencing factors of shear capacity of beams are analyzed.Referring to the formula in the current code of our country,the calculation formula of shear capacity of SFCB beam is obtained.The calculated value is in good agreement with the experimental value,and has a certain safety reserve.The shear calculation formula of SFCB beam is extended to the shear calculation of FRP reinforced beam.The calculation formula also has a certain practical significance for the application of FRP materials.