【正文】 成的試件，在標(biāo)準(zhǔn)情況下養(yǎng)護(hù) 28天。 二、實(shí)驗(yàn)內(nèi)容 試驗(yàn)在 60噸萬能試驗(yàn)機(jī)上進(jìn)行。然而它對(duì)其它性質(zhì)的改進(jìn)很小，因此在正常實(shí)驗(yàn)方法下如此低得的纖維含量很難難得到鋼纖維混凝土軸拉應(yīng)力 —— 應(yīng)變曲線的平穩(wěn)段。為了找到一個(gè)合適易行的方法來研究 SFRC軸拉性能人們做了很多工作并且有報(bào)告稱可通過添加剛性組件方法來獲得軸拉全曲線。在試驗(yàn)裝置中添加了四個(gè)高強(qiáng)鋼桿以增大試件的卸載剛度，并通過在試件兩端添加球鉸來消除試件的初始偏心率。三種試件的平均強(qiáng)度見于表一。對(duì)于高強(qiáng)度鋼纖維混凝土諸如抗拉能力等拉伸特性也由此得到。由于黏結(jié)強(qiáng)度的提高，基體強(qiáng)度越高，該纖維對(duì)高強(qiáng)混凝土軸拉極限強(qiáng)度的增強(qiáng)效果越好。兩圖中曲線的上升趨勢很相似。其定義為： (2) 式中 : fft 為鋼纖維混凝土軸拉極限強(qiáng)度； A 為軸拉試件的破壞橫截面面積。 F1 型纖維從基體中拔出其實(shí)是一個(gè)纖維端鉤被拉直，纖維端部周圍混凝土被擠碎的過程。摩擦力隨基體強(qiáng)度的升高而增大，且該黏結(jié)類型的拔出破壞是一個(gè)持續(xù)過程，因此基體強(qiáng)度升高對(duì)摻有這兩種鋼纖維的混凝土韌性起積極作用。另外，鋼纖維摻量的提高可以大大地改善曲線的豐滿程度。 曾經(jīng)有許多鋼纖維混凝土軸拉應(yīng)力一應(yīng)變?nèi)€模型提出大多數(shù)為分段函數(shù)，以應(yīng)力峰值點(diǎn)為分界點(diǎn)。 五、 理論曲線與試驗(yàn)結(jié)果的比較 鋼纖維高強(qiáng)混凝土軸拉應(yīng)力一應(yīng)變理論曲線和試驗(yàn)曲線的比較如圖 l2所示 (以試件 F3— 6010為例 )。通過對(duì)實(shí)驗(yàn)曲線的分析與回歸，給出了考慮上述影響因素的鋼纖維高強(qiáng)混凝土軸拉應(yīng)力應(yīng)變?nèi)€表達(dá)式。 外文翻譯原文 Concrete stress test 1 Test Introduction The tensile properties of concrete can be enhanced substantially by incorporating high strength and small diameter short steel fibers． which leads to the steel fiber reinforced concrete(SFRC)． In conventional SFRC， the steel fiber content is usually within the range of 0． 2％ —2％ by volume． At such a low 6her content． the tensile response of SFRC would assume a nonhardening type． which is characterized by the widening of a single crack， similar to an unreinforced concrete ． The contribution of fibers is apparent in the post—cracking response, represented by an increase in post—cracking ductility due to the work associated with pullout of fibers bridging a failure crack. However， improvements in some other properties are insignificant ． Moreover，the softening segment of the stress—strain curve of SFRC with such a low fiber content under uniaxial tension is difficult to be got with normal experimental methods． Many works have been done to find a suitable and relatively easy way to analyze the tensile characteristics ． And it was reported that the whole curve could be got on a normal testing machine with stiffening ponents added. 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, SFRCdoped 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 fiberreinforced 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， spherichinges 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 ％ 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 pressive 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 s． Averaged results for 3 specimens are given in Table 2． 0rdinary Portland cement(yielded by Dalian Huaneng Onoda Cement Company)of 32． 5 and 52． 5 (according to China standard) were chosen． River sand(modulus of fineness is )and crushed limestone coarse aggregates(5—20 Bin) were used． Table Matrix code Strength grade Of Cement Kg/m3 u/c ratio Sand ratio Sand Kg/m3 Crushed Strne Water reducing Compressive Strength cement (ISO) Kg/m3 Mpa C30 450 4 667 1155 C60 500 5 602 1223 DK5 C80 600 9