【正文】 cracking moment significantly. The cracking moment is given by Mcr=(fr? fcs)Ig / yt, where fcs is maximum shrinkageinduced tensile stress in the uncracked section at the extreme fibre at which cracking occurs（Gilbert 2003）. （2）where distribution coefficient accounting for moment level and degree of cracking and is given by （3）and 1= for deformed bars and for plain bars。 Mcr=cracking moment =(frIg / yt)。Ig=moment of inertia of the gross cross section about the centroidal axis [but more correctly should be the moment of inertia of the uncracked transformed section, Iuncr]。 Concrete slabs.1Professor of Civil Engineering, School of Civil and EnvironmentalEngineering, Univ. of New South Wales, UNSW Sydney, 2052, . Associate Editor: Rob Y. H. Chai. Discussion open untilNovember 1, 2007. Separate discussions must be submitted for individualpapers. To extend the closing date by one month, a written request mustbe filed with the ASCE Managing Editor. The manuscript for this technicalnote was submitted for review and possible publication on May 22,2006。 Serviceability。 Deflection。 畢業(yè)設(shè)計(jì) (論文)外文翻譯設(shè)計(jì)（論文）題目： 寧波天合家園某住宅樓 2號(hào)軸框架結(jié)構(gòu)設(shè)計(jì)與建筑制圖 學(xué) 院 名 稱： 建筑工程學(xué)院 專 業(yè)： 土木工程 姓 名： 陳紹樑 學(xué) 號(hào) 09404010421 指 導(dǎo) 教 師： 馬永政、陶海燕 2012 年 12 月 10 日寧波工程學(xué)院本科畢業(yè)設(shè)計(jì)（論文）—外文翻譯外文原稿1Tension Stiffening in Lightly Reinforced Concrete Slabs1R. Ian Gilbert1Abstract: The tensile capacity of concrete is usually neglected when calculating the strength of a reinforced concrete beam or slab, even though concrete continues to carry tensile stress between the cracks due to the transfer of forces from the tensile reinforcement to the concrete through bond. This contribution of the tensile concrete is known as tension stiffening and it affects the member’s stiffness after cracking and hence the deflection of the member and the width of the cracks under service loads. For lightly reinforced members, such as floor slabs, the flexural stiffness of a fully cracked section is many times smaller than that of an uncracked section, and tension stiffening contributes greatly to the postcracking stiffness. In this paper, the approaches to account for tension stiffening in the ACI, European, and British codes are evaluated critically and predictions are pared with experimental observations. Finally, remendations are included for modeling tension stiffening in the design of reinforced concrete floor slabs for deflection control.CE Database subject headings: Cracking。 Creep。 Concrete, reinforced。 Shrinkage。 approved on December 28, 2006. This technical note is part of theJournal of Structural Engineering, Vol. 133, No. 6, June 1, 2007.11Professor of Civil Engineering, School of Civil and Environmental Engineering, Univ. of New South Wales, UNSW Sydney, 2052, Australia. 28寧波工程學(xué)院本科畢業(yè)設(shè)計(jì)（論文）—外文翻譯Journal of Structural Engineering, Vol. 133, No. 6, June 1, 2007. The tensile capacity of concrete is usually neglected when calculatingthe strength of a reinforced concrete beam or slab, eventhough concrete continues to carry tensile stress between thecracks due to the transfer of forces from the tensile reinforcementto the concrete through bond. This contribution of the tensileconcrete is known as tension stiffening, and it affects the member’sstiffness after cracking and hence its deflection and thewidth of the cracks. With the advent of highstrength steel reinforcement, reinforcedconcrete slabs usually contain relatively small quantities oftensile reinforcement, often close to the minimum amount permittedby the relevant building code. For such members, the flexuralstiffness of a fully cracked cross section is many times smallerthan that of an uncracked cross section, and tension stiffeningcontributes greatly to the stiffness after cracking. In design, deflectionand crack control at serviceload levels are usually thegoverning considerations, and accurate modeling of the stiffnessafter cracking is required. The most monly used approach in deflection calculationsinvolves determining an average effective moment of inertia [Ie]for a cracked member. Several different empirical equations areavailable for Ie, including the wellknown equation developed byBranson [1965] and remended in ACI 318 [ACI 2005]. Othermodels for tension stiffening are included in Eurocode 2 [CEN1992] and the [British Standard BS 8110 1985]. Recently,Bischoff [2005] demonstrated that Branson’s equation grossly overestimates thtie average sffness of reinforced concrete memberscontaining small quantities of steel reinforcement, and heproposed an alternative equation for Ie, which is essentially patiblewith the Eurocode 2 approach. In this paper, the various approaches for including tensionstiffening in the design of concrete structures, including the ACI318, Eurocode 2, and BS8110 models, are evaluated critically andempirical predictions are pared with measured , remendations for modeling tension stiffening instructural design are included. Response after Cracking Consider the loaddeflection response of a simply supported, reinforcedconcrete slab shown in Fig. 1. At loads less than thecracking load, Pcr, the member is uncracked and behaves homogeneouslyand elastically, and the slope of the load deflection plotis proportional to the moment of inertia of the uncracked transformedsection, Iuncr. The member first cracks at Pcr when theextreme fiber tensile stress in the concrete at the section of maximum moment reaches the flexural tensile strength of the concrete or modulus of rupture, fr. There is a sudden change in the local stiffness at and immediately adjacent to this first crack. On the section containing the crack, the flexural stiffn