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In this article，the stress—strain behavior of SFRC under uniaxial tension Was analyzed for different types of fiber．The tensile characteristics of SFRC influenced by the matrix strength and the steel fiber content were studied also．In addition，the stress—strain curves of high strength SFRC with different factors were well acquired．The mechanism of fiber reinforced concrete to enhance research, to obtain steel fiber reinforced concrete in tension curve of the whole process, using the most appropriate method of axial tension, but to make sure the testing methods improved, and the testing machine must have enough stiffness to ensure the testing process stability. Is well known in engineering practice, process, technology and economic conditions due to construction constraints, SFRC-doped fiber volume in the rate of generally not more than 2%, while most of the engineering example, the fiber fraction are about 1%. In this paper the design of the axial tension SFRC material testing, fiber dosage to take 1%, and using different types of fiber-reinforced forms, were analyzed.
2. Experimental Content
The specimens were tested on a 60 kn universal testing machine．Four high steel bars were added to enhance the stiffness of the testing machine．In addition，spheric-hinges were used to abate the initial axial eccentricity of the specimens．．
It was ensured that specimens should be pulled under uniaxial tension by adjusting the four high strength bolts which connect the specimens to the crossbeam．And the difference between the tensile strains of the opposite sides of the specimen should be less than 1 5％ of their mean value．When the fiber content was low (0 and 0.5％ by volume)，the cyclic quire the whole stress—strain.
2．1 Materials
Four types of steel fibers shown in Table were chosen for this test． Three of these fibers (F1，F2 and F3) were hooked—end and the other one(F4)was smooth．
Three concrete mixtures，shown in Table 2，were investigated．Water reducing agents were used in C60 and C80 mixes(DK一5 made by Dalian Structure Research Institute and Sika made in Switzerland respectively). The compressive strengths of these C30，C60，C80 mixes were determined according to “Test Methods Used for Steel Fiber Reinforced Concrete”(CECS 13：89)"8 3 at 28 days using 150 mm×150 mm ×150 mm cube s．Averaged results for 3 specimens are given in Table 2．0rdinary Portland cement(yielded by Dalian Huanaco On-oda Cement Company)of 32．5 and 52．5 (according to China standard) were chosen．River sand(modulus of fineness is 2.6)and crushed limestone coarse aggregates(5—20 Bin) were used．
Matrix
code Strength grade Of cement
(ISO) Cement
Kg/m3 u/c
ratio Sand
ratio Sand
Kg/m3 Crushed
Stane
Kg/m3 Water
reducing Compressive
Strength
（M pa）
C30 32.5 450 0.44 0.36 667 ¬1155 ---- 37.07
C60 52.5 500 0.35 0.33 602 1223 DK-5 67.59
C80 52.5 600 0.29 0.31 535 1190 Sika 82.96
Table
2．2 Specimen
The tensile specimen was bonded to steel padding plates at both ends by tyro weld．A total of 1 1 0 specimens were pided into 22 groups according to certain parameters．The parameters of these specimens are shown in Table 3．