Research On Uniaxial Compression Performance And Constitutive Relationship Of Steel Fiber Reinforced Concrete

FRP(fiber reinforced plastic)reinforced concrete structure is short of poor ductility,because the plain concrete in compression zone is easy to be crushed,which will result in the failure of the structure.Steel fiber reinforced concrete(SFRC)can be used to replace plain concrete in the compression zones of FRP reinforced concrete structures.The bridging effect of steel fibers can effectively control the initiation and expansion of cracks.Therefore,research on the uniaxial compression performance of SFRC is of great significance expanding the applications of FRP reinforced concrete structures.This paper combines the findings of experiments the experiments with theory to study the axial compression performance of 63 cubic and 63 cylindrical specimens(in 21 groups of each type).The proportion of steel fiber in concrete(0%,1.0%,1.3%,and 1.6%),the strength grade of concrete(C30,C40,and C50),and the type of steel fiber(anchor point type,and shear-type)are the experimental variables.The highlights of the research and the results are presented below.(1)Experiments were conducted to test the compressive strength of cubic and cylindrical specimens.Three experimental variables,is the type of steel fiber,the proportion of steel fibers,and the strength of concrete,were used to study the failure characteristics of steel fiber concrete,and the mechanisms for increasing compressive strength.The test results,were analyzed to compare and determine the relationship between the compressive strength of cubic and cylindrical specimens.A computational method for the compressive strength of different types of steel fiber concrete was formulated,which showed good agreement with the experimental result,there by establishing its computational value.(2)Uniaxial compression tests were conducted on cylindrical specimens of different strengths,to study the effects of steel fiber type,and the proportions of steel fiber,on the mechanical properties of steel fiber type,and the proportions of steel fiber on the mechanical properties of concrete.A computational formula for the peak strain was developed,using the characteristics of the fiber as parameters.The feasibility of this formula was verified by comparison with experimental results,and thus an empirical relationship between the ultimate compressive strain and the peak strain was obtained from a linear regression analysis.(3)Based on experimental date,the curves of stress-versus strain for various steel fiber concrete specimens were used to select an appropriate constitutive relationship model.Through comparisons with experimental curves,it was proved that the model could well describe the process of uniaxial compression of steel fiber concrete.(4)Based on a computational model for residual stress and toughness index,the toughness of steel fiber concrete was evaluated.By analyzing the effect on toughness,the design method for determining the proportion of steel fiber to achieve the best overall toughness for CF30,CF40 and CF50 types of concrete,was selected.