索塔锚固区拓扑优化拉压杆模型及预应力构造分析
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摘要
针对混凝土索塔锚固区承载力准确计算及预应力设计难题,提出拓扑优化拉压杆模型,以龙川枫树坝大桥为背景,采用变密度拓扑优化法构建索塔锚固区拉压杆模型,分析索塔锚固区压杆和节点的承载力、计算环向预应力需求数量,建立索塔锚固区节段有限元模型进行预应力构造优化分析,确定预应力沿高度方向布置方式、预应力盲区设计及预应力配置数量,并对优化后的模型进行应力验算。结果表明:分散布束较集中布束产生的锚固区主拉应力更小;在导管处预应力盲区增加短束可均匀提高塔侧壁的预压应力;受材料泊松效应影响,索塔锚固区预应力钢筋必须适量配置;按提出的拉压杆模型及构造优化方式布置预应力钢束可较好满足索塔锚固区受力要求。
In view of the difficulties regarding the bearing capacity accurate calculation and the prestress design for the anchorage zone in concrete pylon,the topologically optimized strutand-tie model was proposed.The Fengshuba Bridge in Longchuan was taken as an example and the strut-and-tie model for the anchorage zone in the pylon was established,using the variable density topology optimization method.The bearing capacity of the struts and nodes of the anchorage zone was analyzed and the amount of the loop prestress required by the anchorage zone was calculated.The finite element model for the segments of the anchorage zone was established as well.The structural optimization analysis of the prestress for the anchorage zone was conducted,the arrangement way of the prestress along the height,the design of the prestress blind areas and the amount of the prestress arrangement were determined and the stress calculation of the optimized model was checked.The results show that the principal tensile stress in the anchorage zone caused by the scattered arrangement of the prestressing tendons is less than that in the anchorage zone caused by the concentrated arrangement of the tendons.The adding of the short prestressing tendons to the prestress blind areas close to the prestressing ducts can uniformly improve the compressive prestress of the side walls of the pylon.Affected by the Poisson effect of the concrete materials,the prestressing tendons for the anchorage zone should be arranged in an appropriate amount.The arrangement of the prestresssing tendons according to the proposed strut-and-tie model and the described structural optimization way can well satisfy the stress requirements for the anchorage zone.
In view of the difficulties regarding the bearing capacity accurate calculation and the prestress design for the anchorage zone in concrete pylon,the topologically optimized strutand-tie model was proposed.The Fengshuba Bridge in Longchuan was taken as an example and the strut-and-tie model for the anchorage zone in the pylon was established,using the variable density topology optimization method.The bearing capacity of the struts and nodes of the anchorage zone was analyzed and the amount of the loop prestress required by the anchorage zone was calculated.The finite element model for the segments of the anchorage zone was established as well.The structural optimization analysis of the prestress for the anchorage zone was conducted,the arrangement way of the prestress along the height,the design of the prestress blind areas and the amount of the prestress arrangement were determined and the stress calculation of the optimized model was checked.The results show that the principal tensile stress in the anchorage zone caused by the scattered arrangement of the prestressing tendons is less than that in the anchorage zone caused by the concentrated arrangement of the tendons.The adding of the short prestressing tendons to the prestress blind areas close to the prestressing ducts can uniformly improve the compressive prestress of the side walls of the pylon.Affected by the Poisson effect of the concrete materials,the prestressing tendons for the anchorage zone should be arranged in an appropriate amount.The arrangement of the prestresssing tendons according to the proposed strut-and-tie model and the described structural optimization way can well satisfy the stress requirements for the anchorage zone.
引文
[1]肖林,叶华文,卫星,等.斜拉桥桥塔钢-混结合段的力学行为和传力机理研究[J].土木工程学报,2014,47(3):88-96.(XIAO Lin,YE Hua-wen,WEI Xing,et al.Study on Mechanical Behavior and Load Transfer of Steel-Concrete Composite Joint of Cable-Stayed Bridge Pylon[J].China Civil Engineering Journal,2014,47(3):88-96.in Chinese)
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[3]刘玉擎,陈聪,郑双杰.钢锚箱嵌固型索塔锚固结构受力机理分析[J].桥梁建设,2015,45(1):33-38.(LIU Yu-qing,CHEN Cong,ZHENG Shuang-jie.Analysis of Force Mechanism of Pylon Anchorage Structure of Fixed-End Steel Anchor Box Type[J].Bridge Construction,2015,45(1):33-38.in Chinese)
[4]崔楠楠,贾布裕,余晓琳,等.斜拉桥单向预应力体系索塔锚固区足尺模型试验研究[J].湖南大学学报(自然科学版),2016,43(5):61-69.(CUI Nan-nan,JIA Bu-yu,YU Xiao-lin,et al.FullScale Model Test Study of Anchorage Zone with OneWay Prestressing Tendons in Pylon of Cable-Stayed Bridge[J].Journal of Hunan University(Natural Sciences),2016,43(5):61-69.in Chinese)
[5]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].)
[6]AASHTO LRFD Bridge Design Specification,Fifth Edition[S].
[7]ACI 318-14,Building Code Requirements for Structural Concrete and Commentary[S].
[8]EN 1992-2-2005,Eurocode 2-Design of Concrete Structures-Part 2:Concrete Bridges-Design and Detailing Rules[S].
[9]熊治华,刘永健,田文民,等.拓扑优化拉杆-压杆模型在索塔锚固区的应用[J].桥梁建设,2013,43(4):74-79.(XIONG Zhi-hua,LIU Yong-jian,TIAN Wen-min,et al.Application of Topologically Optimized Strut-andTie Model to Pylon Anchorage Zone[J].Bridge Construction,2013,43(4):74-79.
[10]孟杰,吴后伟,郑和晖.基于拉压杆模型的混凝土索塔锚固区环向预应力设计方法[J].结构工程师,2016,32(1):5-9.(MENG Jie,WU Hou-wei,ZHENG He-hui.Design Method for Loop Prestress of Anchorage Zone in Concrete Pylon Based on Strut-and-Tie Model[J].Structural Engineers,2016,32(1):5-9.in Chinese)
[11]Bruggi M.Generating Strut-and-Tie Patterns for Reinforced Concrete Structures Using Topology Optimization[J].Computers&Structures,2009,87(23/24):1 483-1 495.
[12]Shao X D,Pan R S,Zhao H,et al.Prestress Loss of a New Vertical Prestressing Anchorage System on Concrete Box-Girder Webs[J].Journal of Bridge Engineering,2014,19(2):210-219.
[2]Qazi S,Michel L,Ferrir E,et al.Strut-and-Tie Model for a Reinforced Concrete Wall Strengthened with Carbon Fibre-Reinforced Polymers[J].Composite Structures,2015,128:87-99.
[3]刘玉擎,陈聪,郑双杰.钢锚箱嵌固型索塔锚固结构受力机理分析[J].桥梁建设,2015,45(1):33-38.(LIU Yu-qing,CHEN Cong,ZHENG Shuang-jie.Analysis of Force Mechanism of Pylon Anchorage Structure of Fixed-End Steel Anchor Box Type[J].Bridge Construction,2015,45(1):33-38.in Chinese)
[4]崔楠楠,贾布裕,余晓琳,等.斜拉桥单向预应力体系索塔锚固区足尺模型试验研究[J].湖南大学学报(自然科学版),2016,43(5):61-69.(CUI Nan-nan,JIA Bu-yu,YU Xiao-lin,et al.FullScale Model Test Study of Anchorage Zone with OneWay Prestressing Tendons in Pylon of Cable-Stayed Bridge[J].Journal of Hunan University(Natural Sciences),2016,43(5):61-69.in Chinese)
[5]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].)
[6]AASHTO LRFD Bridge Design Specification,Fifth Edition[S].
[7]ACI 318-14,Building Code Requirements for Structural Concrete and Commentary[S].
[8]EN 1992-2-2005,Eurocode 2-Design of Concrete Structures-Part 2:Concrete Bridges-Design and Detailing Rules[S].
[9]熊治华,刘永健,田文民,等.拓扑优化拉杆-压杆模型在索塔锚固区的应用[J].桥梁建设,2013,43(4):74-79.(XIONG Zhi-hua,LIU Yong-jian,TIAN Wen-min,et al.Application of Topologically Optimized Strut-andTie Model to Pylon Anchorage Zone[J].Bridge Construction,2013,43(4):74-79.
[10]孟杰,吴后伟,郑和晖.基于拉压杆模型的混凝土索塔锚固区环向预应力设计方法[J].结构工程师,2016,32(1):5-9.(MENG Jie,WU Hou-wei,ZHENG He-hui.Design Method for Loop Prestress of Anchorage Zone in Concrete Pylon Based on Strut-and-Tie Model[J].Structural Engineers,2016,32(1):5-9.in Chinese)
[11]Bruggi M.Generating Strut-and-Tie Patterns for Reinforced Concrete Structures Using Topology Optimization[J].Computers&Structures,2009,87(23/24):1 483-1 495.
[12]Shao X D,Pan R S,Zhao H,et al.Prestress Loss of a New Vertical Prestressing Anchorage System on Concrete Box-Girder Webs[J].Journal of Bridge Engineering,2014,19(2):210-219.