| China has the largest automobile market in the world,and automobile tires are consumables.The number of waste tires called "black pollution" continues to rise every year.In the face of such a large number of waste tyres,recycling is directly concerned with the reuse of resources.In order to ensure the high strength and high toughness of the tire,steel wire,the skeleton material for tire preparation,is made of high quality carbon steel after wire drawing.Its surface is coated with yellow steel or bronze,and its performance is much stronger than that of ordinary steel fibers.The steel wires in industrial recycled tire beads are basically converted into low-quality steel.In this paper,steel fibers in tires are prepared to replace steel fibers in the market.This is not only a better use of steel wires,but also a higher performance steel fibers can be produced.Steel Fiber Reinforced Concrete(SFRC)is a composite material with super-high tensile strength,super-high modulus of elasticity and excellent tensile properties.It can be used as an ideal material to improve the tensile and shear properties of ordinary concrete members.In the concept of aseismic design,it is required that the structure should guarantee strong columns and weak beams,strong shear and weak bending,strong joints and weak components,and the concept of strong joints and weak components is particularly important,because the shear bearing capacity of joints as the hub of structural transmission and distribution of internal forces,as the joints of weak parts,is related to the safetyof the whole building.Recovery of steel fibers reinforced concrete is used to replace ordinary concrete in the core zone of beam-column joints in order to enhance the shear resistance of the plastic hinge zone and the energy dissipation capacity of the structure.In this paper,the basic mechanical properties and failure modes of recovery of steel fibers reinforced concrete specimens with different volume fractions are tested.The effects of different volume fractions of steel fiber on the mechanical properties of SFRC are analyzed.The experimental results show that the ultimate tensile strain of SFRC specimens can reach 2.4% and the deformation energy of SFRC specimens can reach 2.4% when the volume fraction of steel fiber is 2%.The strength and toughness are more remarkable.Through the low-cycle reciprocating load tests of beam-column side joints and a common concrete joint with four different volume fractions of recovery of steel fibers,the crack development process and failure modes in the four stages of initial crack,opening crack,limit crack and failure of five T-joints are described.The dense crack patterns in the core area and beam end are compared,and the shear failure and failure modes in the core area of concrete joints are determined.Bending failure of beam end;For load-displacement hysteresis curve and skeleton curve of five side joints,the stiffness degradation and strength degradation of joints are compared and analyzed,and the ductility and energy dissipation capacity of joints are judged comprehensively.It is found that recovery of steel fiber reinforced concrete material plays a great role inimproving the seismic performance of joints and shear capacity of core area,and with the increase of recovery of recovery of steel fiber content.Additionally,the more obvious the improvement is.Using Abaqus finite element analysis software,material properties are defined reasonably,test conditions are fully taken into account,and appropriate boundary conditions are found for finite element simulation.The simulation results are compared with the test results,and the results show that they are in good agreement. |
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