外文翻译预应力碳纤维布加固钢筋混凝土梁抗弯性能研究.doc

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1、翻译材料 题目：预应力碳纤维布加固钢筋混凝土梁抗弯性能研究出处：Web Mining and Web-based Application, 2009. WMWA 09. Second Pacific-Asia Conference .目 录第一节1 Abstract1 2 英文论文原文部分1第二节1 汉语翻译部分 8 第一章Research on Deflection of Strengthening Concrete Beam with Prestressed CFRP SheetsWANG Xiang yang, JI Shao bo, ZHAO Guang huiSchool of Tr

2、ansportation, Wuhan University of TechnologyWuhan, China, 430063Wangxy2003Abstract：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 about the deflection

3、 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 the deflection of the structures because the prestressed CFRP sheets are generally thin with small m

4、oment of inertia for the structural sections Keywords: prestressed; strengthening; theoretic formulas; deflection;1 IntroductionCarbon fiber reinforced plastic (CFRP) sheets which are characteristic of high strength, light weight and anticorrosion are widely adopted in strengthening, but the capacit

5、y of high strength in CFRP cant 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 researches of this technology and for the engineering practices.Figure1

6、 Carbon fiber reinforced plastic sheetsTaking the currently widely used box girder bridges as a model, this paper derives the method of calculating the deflection of bridges strengthened with prestressed CFRP sheets and theoretically analyzes the mechanical behaviors of the structures after the stre

7、ngthening.2 Calculation of the deflection2.1 Calculation principleWhen 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 tensile area may have already

8、 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 rigidity is calculated segment by segment according to the moment of the combination for short-term action effects u

9、nder the action of cracking moment cr M ： B0= 0.95EC I0 （1）under the action of moment Ms-Mcr: Bcr=EcIcr （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 componen

10、ts is composed 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 displacement generated by CFRP sheets prestress should be considered. The deflectio

11、n of prestressed CFRP sheets mainly includes the following four parts:1) Deflection under the action of permanent load2) Displacement generated by prestressed steelbars3) Deflection under the action of live load4) Displacement generated by prestressed CFRPsheets2.2 Deflection under the permanent and

12、 live load （3）In which:M p bending moment caused by the action of permanent load and live load at any section x；M x bending moment at any section at virtual state x；I0 converted second moment of cross section after the strengthening of CFRP sheets；I cr converted second moment of cracking section aft

13、er the strengthening of CFRP sheets；2.3. Displacement generated by the prestressed steel Under the prestress of steel strands, the moment of inertia of prestressed concrete members should adopt that of the pretension stage. The displacement is calculated according to the following formula: （4）In whi

14、ch， M pe bending moment caused by existing pretension of steel strands at any section x； I n moment of inertia of the members at the stage of longitudinal steel strands pretension；2.4.Displacement generated by prestressed CFRP sheetsUnder CFRP sheets prestress, the moment of inertia of prestressed c

15、oncrete members should take the converted second moment of area at the strengthening stage. The displacement is calculated according to the following formula: （5）In which M cfe bending moment caused by CFRP sheets existing pretension at any section x；3. Analysis of rigidityRigidity B0 and B cr are d

16、ecided by 0 I and I cr . The paper is to derive the calculation method of prestressed CFRP strengthening concrete box girderssection I0 and I cr under the premise that the depth of the tensile area is covered by the web (as shown in Fig.2).According to Reference 5, the members work with cracks. At t

17、he tensile area the concrete fails and transforms the tension on it to the longitudinal reinforcement which at this stage does not yield and the compressive stress of the concrete takes the shape of triangle. With the CFRP sheets, the sectional area of the steel bar and CFRP sheets should be convert

18、ed into the concrete sectional area which is located at the gravity center of the steel bar and the CFRP sheets separately.3.1 Calculation of IcrThe moment of inertia I cr of the converted section of cracking section for central axis is:3.2. Calculation of i s calculated by the section composed of t

19、he cross section area of the concrete and the converted area of plain reinforced bars, prestressed steel strands and prestressed CFRP sheets.In which,Xthe depth of compression x can be calculated by the static balancing of the tensile area, the compression area and the neutral axis.bthe width of the

20、 web of the I-Sectionh-the depth of the web of the I-Section the effective width of the compressed flange of the I-Sectionthe effective depth of the compressed flange of the I-Sectionb f the effective width of the tensile flange of the I-Sectionh fthe effective depth of the tensile flange of the I-S

21、ectionthe ratio of the elastic modulus of the steel bar to that of the concretethe ratio of the elastic modulus of the prestressed steel strands to that of the concrete -the ratio of the elastic modulus of the CFRP sheets to that of the concreteAccording to equations （ 6 ） and （ 7 ） , the reinforcem

22、ent of CFRP sheets changes the rigidity of the 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 why the strengthening of CFRP sheets

23、does little in changing the rigidity of the structure in long span bridges.4. ConclusionsThe analysis above shows that: The influences of prestressed CFRP sheets on deflection mainly lie in altering the rigidity of the section and causing displacement in the members. For long span bridges, altering

24、the thickness of CFRP sheets can not dramatically ameliorate the deflection of midspan in bridges. 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

25、on the rigidity.References1 Chinese National Standards, “Concrete Structure Design Specification-GB50367-2006,” Beijing：ChinaArchitecture & Building Press，2006.2 Li Liankun, “Structural Mechanics,” Beijing：HigherEducation Press，19963 Chinese Standards of Ministry of Communication, “Code for Design o

26、f Highway Reinforced Concrete and Prestressed Concrete Bridges and Culverts-JTJ062-2004,” Beijing：China Communications Press，20044 Chinese National Standards, “Concrete Structure Design Specification- GB50010-2002,” Beijing,Peoples Republic of China Ministry of Construction,20025 Ye Jian shu, “Princ

27、iple of Structural Design,” Beijing:China Communications Press，2005,56 X.Y. Wang，S.B. Ji ，P. Zhong, “Study on Long Span Bridge with Externally Bonded Prestressed CFRP Sheets,” ICHMM2008, 1647-1650 Authorized.预应力碳纤维布加固钢筋混凝土梁抗弯性能研究（王向阳 季少波 赵光辉 武汉理工大学交通运输学院430063）摘要：在混凝土结构加固中，碳纤维布作为一种新材料，已经在实际工程中被广泛使用。

28、预应力碳纤维布同时，预应力碳纤维布除了具有碳纤维布的优良性能外,还可以提高梁的承载能力。本文主要研究了采用预应力碳纤维布加固对原混凝土结构的挠度和刚度的影响，并且推导了相关的理论公式。结果表明，由于预应力碳纤维布比较细小，通常对结构部分只会产生小的惯性矩作用，因此采用预应力碳纤维布进行加固不会明显地引起改变原结构变形的改变。关键词：预应力 碳纤维布 加强 理论公式 挠度 1 简介碳纤维增强塑料（CFRP）布（板）具有高强、质轻、耐腐蚀的特性，因而被广泛地有应用在加固中，但是在加固中采用一般的方法，碳纤维复合材料的高强性能力并不能得到充分发挥。相反，预应力碳纤维布（如在图1所示）则可以在使用中大

29、为改善构件的力学性能，从而对推动该项技术的研究发展以及工程应用起到重要作用。本文以当前广泛使用的箱形梁桥为模型，推导了使用碳纤维加固后桥梁挠度的计算方法和并且对结构加固后的力学性能做了理论上的分析。2 挠度计算2.1 计算原则当采用碳纤维布对混凝土梁进行加固时，混凝土预应力板梁的组成部分通常会受到荷载的作用；钢筋在受到拉应变作用的同时,受拉区混凝土可能已经产生裂缝。因此,在使用过程中的结构变形应该单独计算。弯曲刚度的计算方法是按照组合弯矩以B型预应力混凝土构件混凝土作为参照，根据参考文献3，逐段来进行计算的，而其中的组合弯矩是由于在开裂弯矩作用下短期荷载的作用而产生的。 B0= 0.95EC

30、I0 （1）在极限和开裂弯矩的作用下有以下公式：Bcr=EcIcr （2）预应力碳纤维布对挠度的的影响主要在于它能改变截面的刚性和引起构件产生位移。预应力混凝土构件的挠度是由两部分组成：由偏心预拉力产生的位移和由外部荷载产生的位移（永久荷载和活荷载）。对于用预应力碳纤维布加固的混凝土构件，由于碳纤维布而产生的位移应该被考虑。预应力碳纤维布加固后结构产生的挠度主要包括以下四个部分： 1）永久荷载作用下的变形2）预应力钢筋作用下产生的位移3）活荷载作用下的变形4）预应力碳纤维布作用下产生的位移2.2 活荷载和永久荷载作用下的变形 （3）其中：由永久荷载和活荷载作用的行用在任意截面x产生的弯矩；在任

31、何实际状态x下的弯矩; 用碳纤维布加固混凝土后横截面的二次转换弯矩；用碳纤维布加固混凝土后开裂截面的二次转换弯矩。2.3 预应力钢筋产生的位移在钢绞线的预拉力作用下，预应力混凝土的惯性矩通常应该采用预拉阶段的惯性矩。位移的计算应采用以下公式： （4）其中：在任意截面由于现存钢绞线的预应力产生的弯矩 在纵筋钢绞线预拉阶段构件的惯性矩。2.4 预应力碳纤维布作用下产生的位移在预应力碳纤维布作用下，预应力混凝土的惯性矩应该采用预拉阶段的惯性矩。位移按照下列公式计算： （5）其中：在任意截面x由于现存的碳纤维布预应力所产生的弯矩3 刚度的分析刚度和由和所决定。刚度分析的目的在于推导预应力碳纤维布加固箱

32、梁 和 的计算方法。在受拉区， 和 受拉区的深度由腹板传递（如图2所示）。按照参考文献5，构件带裂缝工作，受拉区混凝土破坏并且将拉力传递给纵筋；在这个阶段钢筋没有屈服受压区混凝土的应力呈三角形分布。3.1 Icr的计算裂缝截面对中心轴的折算偏心距由以下公式来进行计算。3.2 的计算要根据组成的混凝土截面和折算钢筋截面（普通钢筋、预应力钢绞线和预应力碳纤维布）来计算。其中，X受压区高度，x可以根据静态平衡的拉伸面积、受压区面积以及中和轴来计算。 b“”字形截面的腹板宽度；h“”字形截面腹板深度；“”字形截面受压翼缘板的有效宽度；“”字形截面受压翼缘板的有效高度；b f“”字形截面受拉翼缘板的有效

33、宽度； h f“”字形截面受拉翼缘板的有效高度； 普通钢筋弹性模量与混凝土弹性模量的比值； 预应力钢绞线弹性模量与混凝土弹性模量的比值； 碳纤维布的弹性模量与混凝土弹性模量的比值。根据公式6与公式7，碳纤维布加固的钢筋能够很明显地改变截面的刚度。尽管碳纤维布具有强度高的特性，但是它们通常非常薄，并且偏心距很小。因此，它们对结构的刚度影响较小，这也是为什么采用碳纤维布加固大跨度桥梁后结构刚度会改变很小的原因。 4 结论上述分析表明：预应力碳纤维布对结构变形的影响主要表现在于它能够改变截面的刚度和引起构件的位移。对于大跨度桥梁来说，改变了碳纤维片的厚度并不能很明显地改变桥梁跨中的挠度。这个特点可以

34、通过有限元分析的方法来进行说明：虽然碳纤维布具有强度高的特点，但是由于它的厚度薄，面积与惯性矩都比较小。因而，采用碳纤维布加固后，对截面刚度造成的影响相对比较小。参考资料 1中华人民共和国国家标准“混凝土结构设计规范- GB50367 2006，北京：中国建筑工业出版社，2006。 2李濂昆，结构力学，北京：的高等教育出版社，1996。 3交通部中国标准，对公路设计规范钢筋混凝土预应力混凝土桥梁及涵洞，JTJ062 2004，北京：中国交通出版社，2004。4中华人民共和国国家标准“混凝土结构设计规范- GB50010 2002，北京：中华人民共和国中国建设部，卫生部2002年。 5叶建树，结构设计原理，北京：中国交通出版社，2005,5。 6 X.Y.王森基籍，第钟，大跨径桥梁的研究与体外粘结预应力碳纤维复合材料。