2023年全國碩士研究生考試考研英語一試題真題(含答案詳解+作文范文)_第1頁
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1、1850 英文單詞, 英文單詞,9400 英文字符,中文 英文字符,中文 2900 字文獻(xiàn)出處: 文獻(xiàn)出處:Danilov A I. Some aspects of CFRP steel structures reinforcement in civil engineering[J]. Procedia Engineering, 2016, 153: 124-130.Some aspects of CFRP steel structur

2、es reinforcement in civil engineeringDanilov A.I.AbstractThe FRP materials application in various branches of technology is under examination for at least for about half a century. In civil engineering the most attention

3、 was given to practical aspects of FRP application for RC (reinforced concrete) elements strengthening. As for steel structures there is much less done in this field, high elastic modulus of steel being one of the critic

4、al points for this delay. Bonding between the adherents represents another problem point when dealing with the FRP reinforcement of steel structures. In RF there are few works concerning this problem.In this paper the ca

5、se of axial tension is considered and formulae for the ultimate bonding layer length and other parameters are given with worked numerical examples. Also some prospects of application of CFRP in building are discussed.Key

6、words: steel structures; carbon fiber reinforced polymers (CFRP); CFRP Strengthening, axial tension; adhesion; bonded connection1. GeneralCarbon fiber reinforced polymers (CFRP) application in strengthening structural el

7、ements is being rapidly developed in recent several decades. Compared to conventional using steel variants of reinforcement the CFRP have much higher strength-to-weight ratio, are easy to handle and apply, don’t need any

8、 heavy lifting and handling equipment. These qualities make CFRP to be advantageous for repair, retrofit and rehabilitation of civil engineering structures.A state-of-the-art review of progress in this emerging and rapid

9、ly developing area in Russian Federation with an extensive list of citations is presented in [1]. By now many publications can be found on experimental and theoretical investigations aimed on obtaining of reliable data a

10、bout behavior of steel-CFRP systems in tension, compression and bending ([2-9] etc.).CFRP may be high strength (hsCFRP), high modulus (hmCFRP) and, most recently, ultra-high modulus (uhmCFRP). Generally an increase in CF

11、RP stiffness is accompanied by a reduction in strength and rupture strain of the fibres and also by increase in cost. The modulus of the FRP selected for a particular application should be compatible with the substrate m

12、aterial for effective strengthening application. For this reason, CFRP materials should be used in most cases for steel substrate.The key problem is connection between strengthened steel elements and CFRP reinforcement.

13、Here may be distinguished relatively popular bonded and less developed unbounded joints. The application of first kind connections is overvelming in RC (reinforced concrete) elements strengthening.Epoxy resin systems are

14、 most commonly used as the matrix in hand lay-up applications and as the adhesive in plate bonding techniques. Polyester resin systems are often used as the matrix material in preformed composite materials such as those

15、used for plate bonding applications.The epoxy resins are usually much stronger than concrete and in criteria of durability of Minimal necessary glue layer lengthThe effective (rational) for accepted value of P≤[P] glue l

16、ayer length (further lengthening does not result in decrease of shear stress in glue) may be calculated by a number of iterations using the expressionIt may be taken as approximately (3 to 4) dmin or more.The worked Exam

17、ple 1Conditions:The two steel tapes of 50x5 cross-sectional dimensions are glued symmetrically on the top and bottom with two tapes of 50 mm width and 1.2 mm depth each (fig. 1). The necessary and effective bond layer le

18、ngths are to be defined for given assembly parameters.Table 1. Steel element parameters:b, mm t, mm As, mm² Es, MPa (AE)s, N50 5 250 206000 51500000Table 2. CFRP tapes parameters:bp, mm tp, mm Ap, mm² Ep, MPa (

19、AE)p, N100 1.2 120 300000 36000000Table 3. Glue layer parameters:Ga, MPa ta, mm Ga /ta Ras, MPa700 1 700 15Calculations:Using (2), ? = 0.057478. Using (1), [P] = 26097 N. Accepted tension force value is P = 25000 N Using

20、 (4), Y = 0.958. Using (3), dmin = 33 mm.Using (5) :Table 4d, mm 33 50 100 150 200?max, mm 15.031 14.461 14.370 14.369 14.369So, for given parameter values of bonded connection the ultimate applied tension force value is

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