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1、預應力損失對大跨度PC連續(xù)梁橋撓度的影響卜建清崔金燦(石家莊鐵道大學,石家莊050043)摘要:研究目的:近年來國內(nèi)外多座大跨度預應力混凝土連續(xù)梁橋在通車一段時間后主跨跨中出現(xiàn)較大的撓度,不但影響了過橋車輛的舒適性和安全性,而且威脅著橋梁的安全,縮短了橋梁的使用壽命。本研究旨在分析預應力損失對大跨度連續(xù)梁橋長期撓度的影響規(guī)律,為采取有效的設計、施工及加固等措施抑制大跨度預應力混凝土連續(xù)梁橋跨中持續(xù)下?lián)咸峁├碚撘罁?jù)。研究結論:(1)大跨預應力混凝土連續(xù)梁橋撓度是長期增長的,增長速率不確定,其跨中撓度隨跨徑的增
2、大而增大,增長率與跨徑的大小、預應力損失程度都有著密切關系,且橋梁跨度越大,主跨跨中撓度受預應力損失影響越明顯;(2)橋梁頂板縱向預應力損失比底板縱向預應力損失對跨中撓度的影響顯著;(3)混凝土收縮徐變及由其引起的預應力損失是引起大跨PC連續(xù)梁橋跨中下?lián)系闹饕?(4)該研究成果可應用于大跨度預應力混凝土連續(xù)梁橋優(yōu)化設計。關鍵詞:大跨度預應力混凝土連續(xù)梁橋;預應力損失;收縮;徐變;長期撓度中圖分類號:U448.215,U448.35文獻標識碼:AImpactsofPrestressLossontheDeflec
3、tionforLarge-spanPrestressedConcreteContinuousGirderBridgesBUJian-qing,CUIJin-can(ShijiazhuangTiedaoUniversity,Shijiazhuang,Hebei050043,China)Abstract:Researchpurposes:Inrecentyearsseverallarge-spanprestressedconcretecontinuousgirderbridgesappearlargedeflecti
4、oninthemainspanafteropenedaperiodoftimeathomeandabroad,whichnotonlyinfluencesthecomfortandsecurityofthepassingvehicle,butalsothreatensthesafetyofthebridgeandshortenstheservicelifeofthebridge.Thisstudyaimstoanalyzehowtheprestresslossaffectlong-termdeflectionof
5、large-spancontinuousgirderbridge,theresearchconclusionsmaybethetheorybasisfortakingeffectivemeasurestocontrolthecontinuousdown-warpinginthedesign,constructionandreinforcementforlarge-spanprestressedconcretecontinuousgirderbridgeacross.Researchconclusions:Thed
6、eflectionoflarge-spanprestressedconcretecontinuousgirderbridgesislong-termgrowth,anditsgrowthrateisuncertain.Themid-spandeflectionincreaseswiththespanlength,thegrowthratehasacloserelationshipwiththespanlengthandprestresslossdegree,andtheprestresslosseffectism
7、oreobviouswhenbridgespanlengthisgreater.Theprestresslossoftopdeckhasmoreeffectonmid-spandeflectionthanthatofbottomslab.Thecreepandshrinkageofconcreteandtheprestresslosscausedbythesearethemainreasonofmid-spandeflectionlarge-spanprestressedconcretecontinuousgir
8、derbridges.Thisresearchresultscanbeappliedtooptimizationdesignandconstructionforlarge-spanprestressedconcretecontinuousgirderbridges.Keywords:Large-spanprestressedconcretecontinuousgirder