Experimental Study On Bending Behavior Of Layered Hybrid Steel Fiber Reinforced High Strength Recycled Concrete Beams

In this paper,fly ash and silica fume are used to replace part of cement,Replacing some natural aggregates with recycled coarse aggregates,and steel fiber reinforced high strength recycled concrete is prepared by changing different ways of adding steel fibers.In order to reduce the use of steel fibers,steel fibers are laid out in the tensile zone of concrete in a" layered" way,which effectively reduces the use of steel fibers.At the same time,the utilization ratio of steel fibers is improved.Firstly,the influence of steel fibers on the basic mechanical properties of high strength recycled concrete is studied by changing the different mixing methods.At the same time,the influence of different layers and dimensions on the ultimate load,failure form of beams,load-deflection curve,initial cracking load and strain analysis of tensioned steel bars is analyzed.It is concluded that the addition of steel fibers has no obvious effect on improving the compressive strength of concrete,but can effectively improve the splitting tensile strength,elastic modulus,tension-compression ratio and other properties of concrete.When steel fibers B and C are mixed,high strength recycled concrete with good mechanical properties can be obtained.At the same time,steel fibers B and C have the most obvious effect on improving crack resistance of beams.Secondly,the combination of mixed steel fibers B and C is selected,and mixed steel fibers are added to the lower tension zone of the reference beam with different thickness.The section heights of the beams are 30 mm,60 mm,90 mm,120 mm,150 mm and 180 mm,respectively.The test results show that the number,width and length of cracks are the smallest when the thickness of hybrid steel fibers is 180 mm,while the thickness of90 mm and 120 mm is slightly worse than that of180 mm,but the crack resistance of hybrid steel fibers is also better.Thirdly,the flexural capacity of laminated hybrid steel fiber high strength recycled concrete and hybrid steel fiber high strength recycled concrete are analyzed in a scientific and reasonable way,and the theoretical formulas are deduced and demonstrated many times.Then the test results and theoretical analysis results are compared comprehensively,and the application is obtained by proposing the correction coefficient.Formulas for flexural capacity of normal sections of steel fiber reinforced high strength recycled concrete beams and layered hybrid steel fiber reinforced high strength recycled concrete beams are given.Finally,with the help of ANSYS finite element analysis software and relevant analysis results,the flexural behavior of laminated hybrid steel fiber reinforced high strength recycled concrete beams is simulated,and the simulation results are thoroughly and comprehensively explored.The results show that the results of theoretical analysis and ANSYS software analysis are highly similar.