资源描述：
《土木工程英语翻译.doc》由会员上传分享，免费在线阅读，更多相关内容在行业资料-天天文库。
1、翻译6Lateralbucklingofbeams6.1IntroductionInthediscussiongiveninChapter5ofthein-planebehaviourofbeams,itwasassumedthatwhenabeamisloadedinitsstifferprincipalplane,itdeflectsonlyinthatplane.Ifthebeamdoesnothavesufficientlateralstiffnessorlateralsupporttoensurethatthisisso,thenitmaybu
2、ckleoutoftheplaneofloading,asshowninFig.6.1.Theloadatwhichthisbucklingoccursmaybesubstantiallylessthanthebeam'sin-planeloadcarryingcapacity,asindicatedinFig.6.2.6.梁的侧面翘曲6.1说明在第五章关于梁的平面内性能的讨论中，假定梁按刚性主平面放置时，梁仅在该平面内倾斜。如果梁没有足够的侧向刚度或侧面支撑，梁会发生平面外屈曲，如图6.1所示。如图6.2所示，当发生平面外屈曲时梁的承载能力会大大减小。
3、27/27Foranidealizedperfectlystraightelasticbeam,therearenoout-of-planedeformationsuntiltheappliedmomentMreachestheelasticbucklingmomentM0b,whenthebeambucklesbydeflectinglaterallyandtwisting,asshowninFig.6.1.Thesetwodeformationsareinterdependent:whenthebeamdeflectslaterally,theapp
4、liedmomenthasacomponentwhichexertsatorqueaboutthedeflectedlongitudinalaxiswhichcausesthebeamtotwist.Thisbehaviour,whichisimportantforlongunrestrainedI-beamswhoseresistancestolateralbendingandtorsionarelow,iscalledelasticflexural-torsionalbuckling.作为一个理想的弹性直梁，当施加弯矩达到弹性屈曲弯矩时，梁才会发生侧
5、向弯曲和扭转变形，发生平面外屈曲，如图6.1所示。这两种变形是相互联系的：当梁侧向倾斜时，所承受的弯矩会对侧向梁轴产生扭矩并引起梁扭转。这种特性，对于抵抗侧向弯曲和扭转能力差的无限制I形梁来说很重要，被成为弯扭屈曲。Thefailureofaperfectlystraightslenderbeamisinitiatedwhentheaddi-tionalstressesinducedbyelasticbucklingcausefirstyield.However,aper-fectlystraightbeamofintermediateslenderne
6、ssmayyieldbeforetheelasticbucklingmomentisreached,becauseofthecombinedeffectsofthein-planebendingstressesandanyresidualstresses,andmaysubsequentlybucklein-elastically,asindicatedinFig.6.2.Forverystockybeams,theinelasticbucklingmomentmaybehigherthanthein-planeplasticcollapsemoment
7、inwhichcasethemomentcapacityofthebeamisnotaffectedbylateralbuckling.理想弹性直梁的屈服始于因为因为弹性屈曲产生的附加应力导致的屈服，然而，受平面内弯曲应力和残余应力的影响，理想弹性直梁的中间部位可能在到达屈服弯矩前先行屈服，并发生塑形弯曲，如图6.2所示。对于短梁，其非弹性屈曲弯矩会大于平面内塑形破坏弯矩，受弯承载力不由侧向屈曲控制。Inthischapter,thebehaviouranddesignofbeamswhichfailbylateralbucklingandyieldin
8、garediscussed.Itisassumedthatlocalbuckli
