预应力混凝土箱梁桥悬浇梁段竖向接缝强度研究
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摘要
为了分析悬臂浇注施工的预应力混凝土(PC)箱梁桥在梁段之间存在的竖向接缝对混凝土整体强度影响,通过2座实桥与室内模型梁的接缝混凝土强度测试和承载能力试验发现:在正常施工条件下,大部分接缝处混凝土强度与腹板一般位置相比存在一定折减,其主要原因在于接缝附近端部混凝土由于振捣比较困难,混凝土沉积不均匀,导致接缝处混凝土质量要比一般位置混凝土质量差;接缝处不同混凝土粗糙度对混凝土箱梁抗拉强度有影响,其开裂荷载比整体一次浇注模型梁有所降低。因此施工中必须控制其接缝质量,增加交界面混凝土粗糙度,以提高新老混凝土结合面的粘结性能。
To analyse the influence of vertical joints lied between cantilever-cast segments of prestressed concrete box girder bridge on concrete strength,the vertical joints of two actual bridges and an interior girder model were applied to test the concrete strength and load-bearing capacity.It is found that(1) the concrete strengths of most vertical joints are lower than the strength in normal position of web under normal construction condition,the main reason of which is the vibrating difficulty and non-uniform deposition of concrete in the vertical joints,resulted in the concrete quality in that position is poor than that in normal position;(2) the tensile strength of concrete at the vertical joints is affected by the roughness of concrete,and the cracking load is lower than that of the whole model of box girder.Therefore,the quality of the vertical joints must be well controlled to improve the roughness and bond of concrete in combining site of old-new concrete during construction.
To analyse the influence of vertical joints lied between cantilever-cast segments of prestressed concrete box girder bridge on concrete strength,the vertical joints of two actual bridges and an interior girder model were applied to test the concrete strength and load-bearing capacity.It is found that(1) the concrete strengths of most vertical joints are lower than the strength in normal position of web under normal construction condition,the main reason of which is the vibrating difficulty and non-uniform deposition of concrete in the vertical joints,resulted in the concrete quality in that position is poor than that in normal position;(2) the tensile strength of concrete at the vertical joints is affected by the roughness of concrete,and the cracking load is lower than that of the whole model of box girder.Therefore,the quality of the vertical joints must be well controlled to improve the roughness and bond of concrete in combining site of old-new concrete during construction.
引文
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[2]何畅.竖向接缝对连续刚构桥后期挠度的影响[J].重庆交通大学学报:自然科学版,2009,28(3):480-483.HE Chang.Influence of Vertical Joints on the Post-construction Deflection of Continuous Rigid Frame Bridges[J].Journal of Chongqing Jiaotong University:NaturalScience Edition,2009,28(3):480-483.
[3]张开敬,赵人达,马忠国.武汉长江斜拉桥主梁分段施工混凝土接缝性能试验[J].西南交通大学学报,1994,29(4):436-441.ZHANG Kaijing,ZHAO Renda,MA Zhongguo.A Studyon the Behavior of the Joints on Cast-in-placeSegmental Box Girder of PC Cable-stayed Highway Bridgeover the Yangtze River at Wuhan[J],Journal ofSouthwest Jiaotong University,1994,29(4):436-441.
[4]钟明全,张开敬.预应力混凝土梁分段灌筑接缝的静力性能研究[J].西南交通大学学报,1994,29(4):429-435.ZHONG Mingquan,ZHANG Kaijing.ExperimentalInvestigation of the Static Behavior of Cast-in-placeJoint in FPC and PPC Beams[J].Journal of SouthwestJiaotong University,1994,29(4):429-435.
[5]詹建辉,陈卉.特大跨度连续刚构主梁下挠及箱梁裂缝成因分析[J].中外公路,2005,25(1):56-58.ZHANG Jianhui,CHEN Hui.Analysis of the Cause forDown-warping and Cracking of Large Span PrestressedConcrete Continuous Bridge[J].Journal of China&Foreign Highway,2005,25(1):56-58.
[6]楼庄鸿.大跨径梁式桥的主要病害[J].公路交通科技,2006,23(4):84-87.LOU Zhuanghong.Main Faults in Large Span BeamBridges[J].Journal of Highway and TransportationResearch and Development,2006,23(4):84-87.
[7]楼庄鸿.现有预应力混凝土梁式桥的缺陷[M].北京:人民交通出版社,2004.LOU Zhuanghong.Existing Prestressed Concrete BeamBridge Defect[M].Beijing:China CommunicationsPress,2004.
[8]王凡.桥梁预应力混凝土施工技术及标准规范实施手册[M].北京:人民交通出版社,2004.WANG Fan.Manual of Practice for Bridge PrestressedConcrete Construction and Standard Code[S].Beijing:China Communications Press,2004.
[9]JTG D62-2004,公路钢筋混凝土及预应力混凝土桥涵设计规范[S].JTG D62-2004,Code for Design of Highway ReinforcedConcrete and Prestressed Concrete Bridges and Culverts[S].
[10]JGJ/T23-2001,回弹法检测混凝土抗压强度技术规程[S].JGJ/T23-2001,Technical Specification for Inspection ofConcrete Compressive Strength by Rebound Method[S].
[11]吴德义.龄期对回弹法检测混凝土强度的影响[J].安徽建筑工业学院学报:自然科学版,2005,13(5):5-7.WU Deyi.Influence of Maintain Duration on Prediction ofConcrete Strength by Rebound Method[J].Journal ofAnhui Institute of Architecture&Industry:Natural ScienceEdition,2005,13(5):5-7.
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