Experimental Study On Flexural Behavior Of Recycled Steel Fiber Reinforced Concrete Beam With BFRP Bars

Fiber reinforced polymer(FRP)bar is a new high-performance bar that can be used to replace traditional steel bar,and has wide application prospects in concrete structures.Among them,basalt fiber reinforced polymer(BFRP)bars have been widely recognized by the engineering community for their advantages such as high cost performance,light weight,high strength,and corrosion resistance.On the other hand,FRP bars reinforced concrete structures have problems such as wide cracks and large deformations.By recycling steel fibers from waste tires,replacing them with traditional industrial steel fibers,and incorporating them into FRP bars reinforced concrete structures,the development of cracks and deformations in concrete structures can be limite.At the same time,it can reduce the cost of steel fiber concrete and improve the environmental pollution caused by waste tires.In this paper,BFRP bars and recycled steel fibers(RSF)reinforced concrete are combined.Experiments and ABAQUS finite element simulations are used to study the flexural behavior of recycled steel fibers reinforced concrete beam with BFRP bars.The main research contents and results are as follows:(1)Based on the flexural test of the recycled steel fibers reinforced concrete beam with BFRP bars,the failure mode,cracking load and ultimate load of the test beam are analyzed.The variation rules of BFRP bars’ stress-strain,deflection,crack development and crack width of the test beams were studied.The influence of the RSF volume content and BFRP bar reinforcement ratio on the flexural behavior of the recycled steel fibers reinforced concrete beam with BFRP bars is comprehensively analyzed.The results show that the failure modes of beams can be divided into concrete crushing failure,equilibrium failure and BFRP bar breaking failure.Increasing the RSF volume content and BFRP bar reinforcement ratio can improve the flexural performance of the recycled steel fibers reinforced concrete beam with BFRP bars.RSF have a significant role in limiting development of cracks and deformations in the test beams.(2)The fractal theory is used to analyze the flexural behavior of the recycled steel fibers reinforced concrete beam with BFRP bars.The fractal characteristics of the cracks distribution were verified.Their fractal dimension is between 0.89 and 1.07.The relationship between the fractal dimension and the load level,the volume of RSF,the reinforcement ratio and the mid-span deflection were discussed.The results show that the fractal dimension has a logarithmic growth relationship with the load level and midspan deflection.In the limit state,the incorporation of RSF reduces the fractal dimension.When the volume content of RSF is 1.5%,the minimum fractal dimension is 0.9722.With the increase of the reinforcement ratio,the cracks on the surface of the beam develop more fully,and the fractal dimension also become larger.(3)The ABAQUS finite element software was used to simulate the flexural test of the recycled steel fibers reinforced concrete beam with BFRP bars.The results were compared and verified with the test results.The results show that the finite element simulation results are in good agreement with the experimental results,which verifies the correctness and reliability of the model for the analysis of the recycled steel fibers reinforced concrete beam with BFRP bars.The finite element simulation results can be used as a reference for the test.(4)Based on the existing codes,combined with the test results and numerical simulations,the calculation methods of the flexural capacity of the recycled steel fibers reinforced concrete beam with BFRP bars under different failure modes,as well as the calculation formulas for the equilibrium reinforcement ratio,are proposed.