PC连续箱梁桥箱梁压应力超限的综合处治
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摘要
为解决预应力混凝土连续箱梁桥因施工缺陷造成的箱梁压应力超限问题,以某预应力混凝土连续箱梁桥为工程背景,提出了箱内采用活性粉末混凝土(RPC)薄层加固、主跨合龙前在主跨侧箱梁最大悬臂端施加临时压重及减小铺装层厚度的综合处治方法,并以有限元分析结果和现场测试结果验证其适用性。结果表明:处治后箱梁压应力超限处的压应力最大降幅为16.8%,并满足现行相关规范的应力限值要求;RPC加固层与原结构整体工作状态良好,局部区域6cm厚的RPC加固薄层可使箱梁整体刚度提高5.8%;对于压应力降幅最大的截面,RPC加固薄层对压应力降低的贡献达58.7%;RPC可实现加固层的轻薄化,所提出的综合处治措施对解决箱梁压应力超限问题有效、实用。
In order to solve the problem of overloading compressive stress in prestressed concrete continuous box girder bridge caused by construction defects,selecting aprestressed concrete continuous box girder bridge as project background,we proposed to take comprehensive treatment measures,such as adopting a thin-layer of reactive powder concrete(RPC)to reinforce in the box,exerting temporary loads at cantilever ends in main span of the bridge before the closure of the main span,and reducing the pavement thickness.Meanwhile,the applicability of the proposed measures was validated by the results of finite element analysis(FEA)and site tests.The results indicate that the compressive stresses at the overloading edges in the box girder after treatment were reduced by a maximum percentage of 16.8% and thus can meet the requirements of the stress limit of current relative design norms;the RPC reinforeced layer can match the original structures in working conditions,and the overall stiffness of the box girder is increased by 5.8% after the 6 cm thick reinforced RPC thin-layer is applied in local regions;the thick RPC reinforced thin layer can lead to decrease in stress by 58.7%for the section with the largest reduction of compressive stress.Therefore,the application of RPC can lighten and thin the reinforcement layer,and the measures proposed in the present study can effectively solve the problem of aforementioned overstressing in box girder.
In order to solve the problem of overloading compressive stress in prestressed concrete continuous box girder bridge caused by construction defects,selecting aprestressed concrete continuous box girder bridge as project background,we proposed to take comprehensive treatment measures,such as adopting a thin-layer of reactive powder concrete(RPC)to reinforce in the box,exerting temporary loads at cantilever ends in main span of the bridge before the closure of the main span,and reducing the pavement thickness.Meanwhile,the applicability of the proposed measures was validated by the results of finite element analysis(FEA)and site tests.The results indicate that the compressive stresses at the overloading edges in the box girder after treatment were reduced by a maximum percentage of 16.8% and thus can meet the requirements of the stress limit of current relative design norms;the RPC reinforeced layer can match the original structures in working conditions,and the overall stiffness of the box girder is increased by 5.8% after the 6 cm thick reinforced RPC thin-layer is applied in local regions;the thick RPC reinforced thin layer can lead to decrease in stress by 58.7%for the section with the largest reduction of compressive stress.Therefore,the application of RPC can lighten and thin the reinforcement layer,and the measures proposed in the present study can effectively solve the problem of aforementioned overstressing in box girder.
引文
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[10]Caijun Shi,Zemei Wu,Jianfan Xiao,et al.A Review on Ultra High Performance Concrete:Part I.Raw Materials and Mixture Design[J].Construction and Building Materials,2015,101:741-751.
[11]刘超,马汝杰,王俊颜,等.超高性能混凝土薄层加固法在槽形梁桥中的应用[J].桥梁建设,2017,47(5):112-116.(LIU Chao,MA Ru-jie,WANG Jun-yan,et al.Application of Reinforcement Method of UHPC Thin Layers to Trough Beam Bridges[J].Bridge Construction,2017,47(5):112-116.in Chinese)
[2]Jun Wang,Jin Xu,Danying Gao.Numerical Relationship Between Creep Deformation Coefficients of Prestressed Concrete Beams[J].Materials and Structures,2016,49(4):1 443-1 453.
[3]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 Reinforced and Prestressed Concrete Bridges and Culverts[S].)
[4]周泳涛,鲍卫刚,刘延芳,等.桥梁加固工程关键技术研究[J].桥梁建设,2010(6):49-52.(ZHOU Yong-tao,BAO Wei-gang,LIU Yan-fang,et al.Study of Key Techniques for Bridge Strengthening Engineering[J].Bridge Construction,2010(6):49-52.in Chinese)
[5]JTG/T J22-2008,公路桥梁加固设计规范[S].(JTG/T J22-2008,Specifications for Strengthening Design of Highway Bridges[S].)
[6]杨俊,周建庭,程俊,等.基于断裂力学的UHPC复合拱圈加固效率研究[J].桥梁建设,2018,48(4):74-78.(YANG Jun,ZHOU Jian-ting,CHENG Jun,et al.Study of Reinforcement Efficiency of UHPC Composite Arch Ring Based on Fracture Mechanics[J].Bridge Construction,2018,48(4):74-78.in Chinese)
[7]Pierre Richard,Marcel Cheyrezy.Composition of Reactive Powder Concretes[J].Cement and Concrete Research,1995,25(7):1 501-1 511.
[8]方志,郑辉,杨剑,等.超高性能混凝土结构的设计方法[J].建筑科学与工程学报,2017,34(5):59-67.(FANG Zhi,ZHENG Hui,YANG Jian,et al.Design Principles for Ultra-High Performence Concrete Structures[J].Journal of Architecture and Civil Engineering,2017,34(5):59-67.in Chinese)
[9]GB/T 31387-2015,活性粉末混凝土[S].(GB/T 31387-2015,Reactive Powder Concrete[S].)
[10]Caijun Shi,Zemei Wu,Jianfan Xiao,et al.A Review on Ultra High Performance Concrete:Part I.Raw Materials and Mixture Design[J].Construction and Building Materials,2015,101:741-751.
[11]刘超,马汝杰,王俊颜,等.超高性能混凝土薄层加固法在槽形梁桥中的应用[J].桥梁建设,2017,47(5):112-116.(LIU Chao,MA Ru-jie,WANG Jun-yan,et al.Application of Reinforcement Method of UHPC Thin Layers to Trough Beam Bridges[J].Bridge Construction,2017,47(5):112-116.in Chinese)