体外横张预应力加固布束方案的探讨

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1、体外横张预应力加固布束方案的探讨秦晓东，朱世峰，钟继卫71文章编号：1003—4722(2010)03—0071—04体外横张预应力加固布束方案的探讨秦晓东，朱世峰，钟继卫(1．江苏海通建设工程有限公司，江苏连云港222001；2．中铁大桥局集团桥科院有限公司，湖北武汉430034)摘要：结合连续刚构桥后期挠度逐渐增大特点，提出首先采用纵向张拉、结构后期运营中采用横向张拉的技术调控连续刚构桥跨中后期挠度。通过分析体外横张预应力束张拉空间可知，伸长率随着预应力束上、下张拉角度的增加而线性增大，布束时应结合最小上、下张拉角选择下弯点位置。通过探讨3种预

2、应力束布置方案可知，当所需调控主梁挠度较小且箱梁高度较高时，可在箱梁内布置预应力束；当所需调控主梁挠度较大且箱梁高度难以满足张拉要求时，可在箱梁腹板外侧或中跨锚固点至L／4(L／3)的箱梁内布置预应力束，但方案选择应以少损伤原结构为宜。关键词：体外预应力；横向张拉；布柬方式；桥梁加固；探讨中图分类号：U445．7l；U448．23文献标志码：AStudyofPrestressingStrandLayoutforStrengtheningwithExternalTransversely。·TensioningPrestressQINXiao—dong

3、，ZHUShi—feng，ZHONGJi—wei。(1．JiangsuHaitongConstructionEngineeringCo．，Ltd．，Lianyungang22200i，China；2．BridgeScienceResearchInstituteLtd．，ChinaRailwayMajorBridgeEngineeringGroup，Wuhan430034，China)Abstract：Inaccordancewiththecharacteristicofgradualincreaseofthelateperioddeflection

4、ofcontinuousrigid—framebridge，thetechniqueoflongitudinallytensioningonlyforthefirsttimeandthentransverselytensioninginthelateoperationperiodisputforwardforadjustingandcon—trollingthelateperiodmidspandeflectionofsuchtypeofthebridge．Fromtheanalysisoftensio—ningspaceoftheexternal

5、transversely—tensioningprestressingstrands，itisknownthattheelon—gationratioofthestrandslinearlyincreaseswiththeincreaseoftheupperandlowertensioninganglesofthestrands．WhentheprestressingstrandsarelaidOUt，thedrapingpointpositionsofthestrandsshouldbeselectedinconsiderationofthemi

6、nimumupperandlowertensioningan—gles．Furtherfromthestudyofthreekindsoftheprestressingstrandlayoutschemes，itisknownthatthestrandscanbelaidinsidetheboxgirderincasethedeflectionofthegirdertobeadjustedandcontrolledislittleandthedepthofthegirderisgreatwhileincasethedeflectiontObeadj

7、us—tedandcontrolledisgreatandthedepthofthegirdercannotmeettherequirementoftensioning，thestrandscanbelaidoutsidethewebofgirderorinthesectionfromthecentralspananchorpointtOL／4(L／3)insidethegirder，however，theselectionofanylayoutschemesshouldcauseaslessdamagetOtheoriginalgirderstr

8、uctureaspossible．Keywords：externalprestressing；transversely—t