大跨径简支转连续箱梁桥收缩徐变效应

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1、第9卷第2期交通运输工程学报Vol.9No.22009年4月JournalofTrafficandTransportationEngineeringApr.2009文章编号:1671-1637(2009)02-0039-06大跨径简支转连续箱梁桥收缩徐变效应1,22222周绪红,乔朋,狄谨,吕忠达,崔婷(1.兰州大学土木工程与力学学院,甘肃兰州730000;2.长安大学公路学院,陕西西安710064)摘要:利用杆系有限元模型计算了大跨径简支转连续箱梁预制和施工过程中的应力分布和线形变化,研究了预应力束二次张拉对收缩徐变的作用。以6×70m连续箱梁为例,按照老化理论原始算法、老化理论修正算

2、法、JTJ023—85规范附录算法与JTGD62—2004规范附录算法,进行了收缩徐变效应对简支状态和连续状态下箱梁结构应力和变形影响的对比分析。分析结果表明:不同算法的收缩徐变效应对各跨跨中或支点应力影响的最大差值均在15%以内,对边跨、次边跨、中跨跨中挠度影响的最大差值分别为36%、79%、54%,其中JTJ023—85规范附录算法计算的挠度最小,JTGD62—2004规范附录算法计算的挠度最大,也最接近实测挠度,因此,收缩徐变理论的计算分析结果可靠。关键词:桥梁工程;预应力混凝土箱梁;收缩徐变;二次张拉;结构变形中图分类号:U448.213文献标志码:AShrinkageandcr

3、eepeffectsoflong-spansimple-supported-to-continuousboxgirderbridge1,22222ZHOUXu-hong,QIAOPeng,DIJin,LUZhong-da,CUITing(1.SchoolofCivilEngineeringandMechanics,LanzhouUniversity,Lanzhou730000,Gansu,China;2.SchoolofHighway,ChanganUniversity,Xian710064,Shaanxi,China)Abstract:Thestressdistributionsa

4、nddeformationsoflong-spansimple-supported-to-continuousboxgirderbridgeduringdifferentconstructionstageswerecalculatedbybarfiniteelementmodels.Theinfluenceofprestressedbarssecond-timestretchingonshrinkageandcreepeffectswasstudied.Takingthe6×70mcontinuousboxgirderbridgeasanexample,accordingtodiffe

5、renttypesofcalculatingmethods,includingtheoriginalalgorithmofagingtheory,themodifiedalgorithmofagingtheory,thealgorithmintheannexofJTJ023—85CodeandthealgorithmintheannexofJTGD62—2004Code,theinfluencesofshrinkageandcreepeffectsonthestressesanddeformationsofboxgirdersduringsimple-supportedstageandc

6、ontinuousstagewerecompared.Computationalresultshowsthatthemaximuminfluencingdiscrepanciesofstressesatmidspansandsupportingpointsarewithin15%,andthemaximuminfluencingdiscrepanciesofdeflectionsatthemid-sectionsofendspan,sidespanandmidspanareseparately36%,79%and54%.Thedeflectioncalculatedbythealgori

7、thmintheannexofJTJ023—85Codeissmallest,whilethatcalculatedbythealgorithmintheannexofJTGD62—2004Codeisbiggestandalsoisclosesttotheactualmeasuredvalue.Itsconfirmedthatthetheoreticanalysisofshrinkageandcreepeffectsisreli