Experimental Study On Mechanical Property Of Steel Fiber-Reinforced High Strength Concrete Beams

Steel fiber-reinforced high strength concrete beams is a new composite structure system which is formed by optimizing the combination of reinforced high-strength concrete beam and section steel.This kind of structure system endows the structure with more superior performance by the way of embedding profiled steel inside,which has the characteristics of high strength,light deadweight and high stiffness.However,due to the high fragility and the low ductility of the high-strength concrete,its tension-compression ratio decreases continuously with the increase of strength grade of concrete,resulting in the inadequate crack resistance in the tensile region of the total structure and reduction of structure ductility.The mixture of steel fiber reinforced materials into the high strength concrete matrix can effectively restrain the cracks and enhance the ductility of the structure.Therefore,this paper carries out the mechanical performance test of several steel fiber-reinforced high strength concrete beams and reveals its destruction characteristics and stress mechanism.the calculation formula suitable for this study was established.The main contents and conclusions of this research are as follows.(1)It carries out static force loading test on 8 steel fiber-reinforced high strength concrete beams,analyzes the different shear span ratio and the impact of steel fiber volume fraction on mechanical property of structures and reveals the failure mode and stress mechanism.The results show that the mixture of steel fiber can effectively improve the ductility and improve the bearing capacity of the structure.(2)Based on the theory of composite strength,the tensile strength of steel fiber reinforced high strength concrete is calculated by the theory method and the test method,respectively.After comparing and analyzing the calculated values with the measured values,it is found that the calculated results of the test method are more consistent with the measured values.The calculation formula of test method is selected and combined with relevant specifications,revise the existing normal section calculation model,introducing the theory that concrete in the core area is always under tension,and finally establishing the calculation formula of flexural bearing capacity suitable for the study object in this paper.(3)It analyzes the steel fiber-reinforced high strength concrete beams normal section crack develop mechanism and modifies the computational formula of the existing maximum crack width in accordance with the related test data and literature.Considering the influence of residual stress of steel fiber reinforced concrete,it introduces the crack width transformation coefficient and the maximum crack width coefficient of different sections and finally establishes the calculation formula of the maximum crack width suitable for the research object in this paper through regression analysis.(4)The steel fiber reinforced high strength concrete flexural specimens were simulated by the finite element analysis software ABAQUS.A finite element analysis model suitable for this study was established by changing the material structure.The reliability of the model was verified by comparing the simulated data with the experimental data.The stress-strain variation law of concrete and section steel was analyzed by using the simulation results,and the stress mechanism of the specimens was revealed...