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1、保證箱梁橋豎向預(yù)應(yīng)力筋有效預(yù)應(yīng)力的探討2010年3月第3期(總138)鐵道工程JOURNALOFRAILWAYENGINEERINGSOCIETYMar20l0NO.3(Ser.138)文章編號:1006—2106(2010)03—0052—05保證箱梁橋豎向預(yù)應(yīng)力筋有效預(yù)應(yīng)力的探徐華軒(中鐵十六局集團(tuán)有限公司,北京100018)討摘要:研究目的:通過理論分析,試驗(yàn),實(shí)踐,研究混凝土箱梁腹板內(nèi)豎向預(yù)應(yīng)力筋預(yù)應(yīng)力損失大,作用效果差的成因,提出對策與措施,以保證豎向預(yù)應(yīng)力作用效果,避免腹板出現(xiàn)主拉應(yīng)力裂紋.研究結(jié)論:設(shè)計(jì)中,對豎向筋控制應(yīng)力與屈服強(qiáng)度的比值進(jìn)行控制;計(jì)算由錨具變形和縫隙壓縮等引起的
2、預(yù)應(yīng)力損失時(shí),取1.65mro的回縮值;增加由錨墊板安裝誤差引起的預(yù)應(yīng)力損失,并取3.3mm的回縮值;考慮混凝土和水泥漿水化熱引起的預(yù)應(yīng)力損失,施工中重視施工工藝的改進(jìn)和完善;控制錨墊板安裝傾角誤差,做到"兩平一直",控制錨墊板與螺帽的夾角在1.以內(nèi);使用扭矩扳手?jǐn)Q緊螺帽,對632和幣25豎向筋的錨固扭矩分別取1200N?m和600N?m;采取二次張拉和超張拉工藝;前段梁與后段梁連接處的4組豎向筋與后段梁的豎向筋同步張拉.關(guān)鍵詞:預(yù)應(yīng)力混凝土;箱梁;豎向預(yù)應(yīng)力;預(yù)應(yīng)力損失;控制中圖分類號:U445.4文獻(xiàn)標(biāo)識碼:ADiscussionontheMeasuresforGuaranteeingEf
3、fectivePrestressofVerticalPrestressedReinforcementofBoxGirderBridgeXUHna—xuan(ChinaRailway16thGroupCo.Ltd.,Beijing100018,China)Abstract:Researchpurposes:Basedonthetheoreticanalysis,testandpractice,theresearchisdoneonthereasonsf0rthebigpretresslossandpooreffectofprestressedreinforcementofthewebplateo
4、fconcreteboxgirder,andthemeasuresforthemarepresentedtoguaranteetheeffectoftheve~iealprestressandavoidtheappearanceofstresscrackonthewebplate.Researchconclusions:Indesign,theratiobetweenthestressandyielddegreeofverticalreinforcementshouldbecontrolled.Thereboundvalueof1.65mmshouldbeadoptedwhencalculat
5、ingthestresslOSScausedbyanchordeformationandgapcompression.Thestresslosscausedbyinstallationerrorofanchorbackershouldbeaddedandthereboundof3.3mmshouldbeused.ThestresslOSScausedbywaterthermalizationofconcreteandeementgroutshouldbeconsideredandtheattentionshouldbepaidtoimprovementoftheconstructiontech
6、niqueinconstruction.Theerrorofinclineangleshouldbecontrolledtomaketwoflatandonestraightandmaketheincludedanglewithin1.wheninstallingtheanchorbacker.Theanchortorqueof1200N?mand600N?mwithtorquespannershouldbeusedto632reinforcementand+25reinforcement.Thetensionandsupertensiontechniquesshouldbeused.Thef
7、ourgroupsofverticalreinforcementsonthejointplaceofthefrontpartandtherearpartofthegirderandthereinforcementsontherearpartofthegirdershouldbetensedatthesametime.Keywords:prestressedconcrete;boxgirder;ve
