外文翻譯---預(yù)應(yīng)力碳纖維布加固鋼筋混凝土梁抗彎性能研究（英文）

1、Research on Deflection of Strengthening Concrete Beam with Prestressed CFRP SheetsWANG Xiangyang, JI Shaobo, ZHAO Guanghui School of Transportation, Wuhan University of Technology Wuhan, China, 430063 Wangxy2003@163.co

2、m Abstract CFRP sheets have been widely used in strengthening concrete structures as a new material and prestressed CFRP sheets can improve the carrying capacity of beams. This paper researched the affection abo

3、ut the deflection and rigidity of concrete structures after strengthening with prestressed CFRP sheets, and derived related theoretic formulas. It is shown that the prestressed CFRP sheets can not dramatically change

4、 the deflection of the structures because the prestressed CFRP sheets are generally thin with small moment of inertia for the structural sections. Keywords: prestressed; strengthening; theoretic formulas; deflection

5、; 1. Introduction Carbon fiber reinforced plastic (CFRP) sheets which are characteristic of high strength, light weight and anticorrosion are widely adopted in strengthening, but the capacity of high strength in CFRP

6、 can't fully exert with general strengthening method. Prestressed CFRP sheets (as shown in Fig.1) can improve the mechanical behaviors of the members in usage and bear great significance in promoting the research

7、es of this technology and for the engineering practices. Figure1 Carbon fiber reinforced plastic sheets Taking the currently widely used box girder bridges as a model, this paper derives the method of calculating the

8、 deflection of bridges strengthened with prestressed CFRP sheets and theoretically analyzes the mechanical behaviors of the structures after the strengthening. 2. Calculation of the deflection 2.1. Calculation principl

9、e When strengthening concrete beams with prestressed CFRP sheets the components are commonly under the action of loads; the reinforced bar have already been under some tensile strain and the concrete in the te

10、nsile area may have already had cracks. The deflection of the structures in usage should be calculated separately. Taking B-type prestressed concrete member as a reference, according to Reference [3], the bending rig

11、idity is calculated segment by segment according to the moment of the combination for short-term action effects. under the action of cracking moment cr M ：0 0 95 . 0 I E B c =（1） under the action of moment cr s M M ? ：

12、 cr c cr I E B =（2） The impacts of prestressed CFRP sheets on deflection mainly lie in altering the rigidity of the section and causing displacement in the members. The deflection of prestressed concrete components is c

13、omposed of two parts： the displacement generated by eccentric pretension and deflection generated by external load（permanent load and live load）.For prestressed concrete members of prestressed CFRP sheets, the displa

14、cement generated by CFRP sheets prestress should be considered. The deflection of 3.2. Calculation of 0 I 0 I is calculated by the section composed of the cross section area of the concrete and the converted area of

15、 plain reinforced bars, prestressed steel strands and prestressed CFRP sheets. 3 ' ' 2 30 ) )( ( 121 ) 2 ( 121f f h b b x h bh bh I ? + ? + =3 2'' ' ) )( ( 121 ) 2 ( ) ( f fff f h b b x h h b b ? + ?

16、 ? +202 ) ( ) 1 ( ) 2 ( ) ( x h A h x h h b b S Esff f ? ? + ? ? ? + α2 2 ' ' ) ( ) 1 ( ) ( ) 1 ( x a h A a x A p p Ep S Es ? ? ? + ? ? + α α2 2 ' ' ) ( ) 1 ( ) ( ) 1 ( x h A a x A fe Ecf p p Ep ? ? + ? ?

17、 + α α（7） In which, X——the depth of compression x can be calculated by the static balancing of the tensile area, the compression area and the neutral axis. b——the width of the web of the I-Section h——the depth of th

18、e web of the I-Section f b′ ——the effective width of the compressed flange of the I-Section f h' ——the effective depth of the compressed flange of the I-Section f b ——the effective width of the tensile flange of the

19、I-Section f h ——the effective depth of the tensile flange of the I-Section Es α ——the ratio of the elastic modulus of the steel bar to that of the concrete Ep α ——the ratio of the elastic modulus of the prestressed steel

20、 strands to that of the concrete Ecf α ——the ratio of the elastic modulus of the CFRP sheets to that of the concrete According to equations （ 6 ） and （ 7 ） , the reinforcement of CFRP sheets changes the rigidity of the

21、section in a very limited way. Though CFRP sheets are of high strength, they are quite thin and of small area and a small section moment inertia. Therefore they generally have a small impact on the rigidity. This is

22、why the strengthening of CFRP sheets does little in changing the rigidity of the structure in long span bridges. 4. Conclusions The analysis above shows that: The influences of prestressed CFRP sheets on deflection ma

23、inly lie in altering the rigidity of the section and causing displacement in the members. For long span bridges, altering the thickness of CFRP sheets can not dramatically ameliorate the deflection of midspan in bridge

24、s. This can be proved by the way of FEM: though CFRP sheets are of high strength, they are quite thin and of small area and a small section moment of inertia. Therefore they generally have a small impact on the rigid

25、ity. References [1] Chinese National Standards, “Concrete Structure Design Specification-GB50367-2006,” Beijing：China Architecture & Building Press，2006 [2] Li Liankun, “Structural Mechanics,” Beijing：Higher Educat

26、ion Press，1996 [3] Chinese Standards of Ministry of Communication, “Code for Design of Highway Reinforced Concrete and Prestressed Concrete Bridges and Culverts-JTJ062- 2004,” Beijing：China Communications Press，2004 [4]

27、 Chinese National Standards, “Concrete Structure Design Specification- GB50010-2002,” Beijing ： People's Republic of China Ministry of Construction， 2002 [5] Ye Jianshu, “Principle of Structural Design,” Beijing：Chin