毕设设计翻译.docx

1、毕设设计翻译Concrete stress experiment1 Introduction In this paper，the stressstrain behavior of SFRC under uniaxial tension Was analyzed for different types of fiberThe tensile characteristics of SFRC influenced by the matrix strength and the steel fiber content were studied alsoIn addition，the stressstra

2、in curves of high strength SFRC with different factors were well acquiredThe 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 m

3、ethods 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 mo

4、st 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 testi

5、ng machineFour high steel bars were added to enhance the stiffness of the testing machineIn addition，spherichinges were used to abate the initial axial eccentricity of the specimensIt was ensured that specimens should be pulled under uniaxial tension by adjusting the four high strength bolts which c

6、onnect the specimens to the crossbeamAnd the difference between the tensile strains of the opposite sides of the specimen should be less than 1 5 of their mean valueWhen the fiber content was low (0 and 0.5 by volume)，the cyclic quire the whole stressstrain.21 Materials Four types of steel fibers sh

7、own in Table were chosen for this test Three of these fibers (F1，F2 and F3) were hookedend and the other one(F4)was smooth Three concrete mixtures，shown in Table 2，were investigatedWater reducing agents were used in C60 and C80 mixes(DK一5 made by Dalian Structure Research Institute and Sika made in

8、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 mm150 mm 150 mm cube sAveraged results for 3 specimens are given in Table 20rdinary Portland cement

9、(yielded by Dalian Huaneng Onoda Cement Company)of 325 and 525 (according to China standard) were chosenRiver sand(modulus of fineness is 2.6)and crushed limestone coarse aggregates(520 Bin) were usedTableMatrixcodeStrength gradeOf cement(ISO)Cement Kg/m3u/cratio SandratioSandKg/m3CrushedStrneKg/m3W

10、aterreducingCompressiveStrengthMpaC3032.54500.440.366671155-37.07C6052.55000.350.336021223DK-567.59C8052.56000.290.315351190Sika82.9622 SpecimenThe tensile specimen was bonded to steel padding plates at both ends by tygoweldA total of 1 1 0 specimens were divided into 22 groups according to certain

11、parametersThe parameters of these specimens are shown in Table 323 Items At the age of 28 daysplain concrete and steel fiber concrete specimens were tested for tensile strength，respectively .The tensile stressstrain curves were acquiredMany other tensile characters of the high strength steel fiber c

12、oncrete such as tensile work，etc were calculated also. Enhanced class steel fiber reinforced concrete toughness category than the strength of steel fiber reinforced concrete an average of 13%; while cracking from the basic to the crack width of 0.5mm interval (the corresponding strain of about 2000)

13、 showed the fracture energy integral: toughening class steel fiber reinforced concrete enhanced class than the fracture energy of steel fiber reinforced concrete an average of 20%. from Table 3 also shows that most of the SFRC first peak corresponds to the limit of tensile strain value and plain con

14、crete rather, in the 100 around, indicating a low rate of fiber-containing incorporation in improving the role of ultimate tensile strain of concrete is not very obvious. The toughening class SFRC second peak corresponds to a much greater strain, up to 1000, From this second peak has greatly enhance

15、d the appearance of toughness. DRAMIX Fiber because of the length of other three kinds of fiber length of 2 times the fracture toughness and better in the test curve can be seen in the strain is attained, the load continues to maintain a high level of intensity, until the strain when the load so as

16、to maintain 10000 its peak level of 50%.3 Results and Discussion31 Crack stress and ultimate tensile strength The crack stress and ultimate tensile strength of different specimens are listed in Table 3The addition of steel fibers into concrete increased its crack stress an d ultimate tensile strengt

17、hAnd the ratios of these two parameters of SFRC to those of plain concreue (with the same mix proportion)are given in Table 3，too311 Effect of matrix strength an(1 fiber type From table 3It can be seen that the effects of steel fibers 0n crack stress are little influenced by the matsix strengthThat

18、is to sayWhen the matrix strength increases, the ratios of crack stresses of SFRC ( with the same type of fibers contained)to those of plain concrete ones with the same mix proportion are invariable However，the condition for ultimate tensile strength is differentWhen the matrix strength increasesthe

19、se ratios of ultimate tensile strengths(shown in Table 3)vary dissimilarly according to the type of steel fiberMoreoverthe increments are bigger than those of crack stress The heightening efficiency of fiber F1 for ultimate tensile strength rises as matrix strength increasesIt is because that the st

20、rength of this kind of fiber is very high(1 100 MPa)No fiber broken was observed during the test and the hookedends of the fibers were straightened when the matrix strength was high(C80)The higher the matrix strength this kind of steel fiber takes on its strengthening effect more efficiently for the

21、 increasing of bond stressThe strengths of fibers F2 and F3 are midhigh(700 MPa)They all have hooked ends and both of their surfaces are coarseWhen the matrix strength was high(C80)fiber breaking occurred in the testAnd this phenomenon impaired the heightening efficiency of these two kinds of steel

22、fiberSo they should be used in middle strength concrete to exert their strengthening effect more efficientlyFiber F4 is smoothand its bond stress with matrix is comparatively lowT1ereforeits strengthening effect is 1ess notable than those of other kinds of fiberBecause of the low bond stressno fiber

23、 broken was found during the test and its heightening efficiency for ultimate tensile strength rises as matrix strength increases312 Effect of fiber content The effect of fiber content on the crack stress and u1ultimate tensile strength was investigated for SFRC contained fiber F3And the fiber conte

24、nt varied from 05 to 15 by volume(shown in Table 3)It can be seen from Fig1 and Fig2 that as the fiber content increases The crack stress and ultimate strength of SFRC improve obviouslyMoreoverthe rising trends of the curves in these two figures are stupendously similarIn other words，the effect of f

25、iber content on the characters of tensile stress of SFRC is positive and consistentTable 4 Fiber type factorsFiber code atF1 0.642F2 0.862F3 0.794F4 0.589 The tensile strength of SFRC can be calculated with the follow formula： (1)where，fft is the ultimate tensile strength of SFRC； the ultimate tensi

26、le strength of plain concrete with the same mixing proportion；a，the fiber type factor，which is shown Table 4； is the fiber content 0f volume and l/d is the aspect ratio of steel fibers.32 Tensile strain and toughness characters321 Crack strain and the strain at peak tensile load The tensile strains

27、were acquired by averaging the readings of the four displacement sensors fixed around the specimenIn addition，the specimens whose difference between the tensile strains of its opposite sides is larger than 15 of their mean value were blanked out The crack strain or the strains at peak tensile load o

28、f SFRC are much bigger than those of plain concrete(as shown in Table 5)And the increments go up as the matrix strength or the fiber content increasesCompared to that on crack strainthe increscent effect of steel fiber onthe strain at peak tensile load is more remarkable322 Tensile work and toughnes

29、s modulus The tensile work was defined as the area under the load-displacement curve from 0 to 05 rainMoreover，a tensile toughness modulus was introduced(shown in Table 5)It was defined as： (2) where，fft is the ultimate tensile strength of SFRC； A，the area of the cross section of specimenBoth these

30、two parameters were quoted to evaluate the toughness characters of SFRC under uniaxial tensionThe tensile toughness modulus is a dimensionless factorCompared to what the tensile work doesit can avoid the influence of the ultimate tensile strength when studying the toughness of SFRC It call be found

31、from Table 5 that the altering regularities of these two factors along with the changes of matrix strength and fiber content are approximateTherefore，the emphasis of analysis was put on the toughness modulus The relationship between the matrix strength and toughness modulus of SFRC with four kinds o

32、f steel fiber are shown in Fig3whose fiber contents are all 1Oby volumetogether with that relationship of plain concreteThe tensile toughness of SFRC is much better than that of plain concreteThe tensile toughening effect of steel fiber is remarkableAs the matrix strength risesThe brittleness of concrete increases obviously，and then the te