大型LNG储罐外罐长期预应力损失分析
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摘要
由于混凝土收缩徐变及钢筋应力松弛的耦合作用,LNG储罐外罐预应力系统将产生长期预应力损失,严重影响储罐的安全性能。为此,基于按龄期调整的有效模量法及混凝土结构设计规范中的相关模型,以国内某大型LNG储罐外罐为研究对象,应用ABAQUS有限元软件,建立了多组模型分别模拟收缩徐变损失、应力松弛损失及其耦合作用下的损失,分析了混凝土收缩徐变及应力松弛的相互作用对长期预应力损失的影响规律,并讨论了双向设置预应力对长期预应力损失的影响。研究结果表明:(1)环向、竖向预应力筋长期损失终值(50年)最大值分别达到张拉控制应力的10.97%、17.02%;(2)环向、竖向预应力筋在收缩徐变和应力松弛耦合作用下的损失分别为收缩徐变损失与应力松弛损失代数和的83.59%和86.33%;(3)提出相互作用折减系数,当收缩徐变损失和应力松弛损失大小相近时的折减系数最小;(4)竖向预应力对环向预应力筋长期预应力损失的影响较为明显。结论认为,该研究成果有助于提高大型LNG储罐混凝土外罐的安全性。
Due to the coupling effect of concrete shrinkage creep and tendon stress relaxation, the prestressed system of the external walls of LNG tanks suffers from long-term prestress losses, which seriously affect the safety performance of the tanks. In this paper, a large LNG storage tank in China was taken as the research object. By using the age-adjusted effective modulus method and the relevant models in the design code of concrete structure, the multiple models were established by using the ABAQUS finite element software to simulate the prestress loss caused by shrinkage creep, stress relaxation and coupling effect. Then, the influence law of the interaction between shrinkage creep and stress relaxation on the long-term prestress loss was analyzed. Finally, the influence of two-way prestress on the long-term prestress loss was discussed. And the following research results were obtained. First, the ultimate(50 years) maximum of long-term losses in circumferential and vertical prestressing tendons reach 10.97% and 17.02% of the tension control stress, respectively. Second, the losses in circumferential and vertical prestressing tendons under the coupling effect of shrinkage creep and stress relaxation are 83.59% and 86.33% of the algebraic sum of shrinkage creep loss and stress relaxation loss. Third, the interaction reduction coefficient is proposed, and it reaches the minimum value when the shrinkage creep loss and the stress relaxation loss are close. Fourth, the effect of vertical prestress on the long-term prestress loss in circumferential prestressing tendons is obvious. In conclusion, the research results are crucial to the design safety of concrete wall of large LNG tanks.
Due to the coupling effect of concrete shrinkage creep and tendon stress relaxation, the prestressed system of the external walls of LNG tanks suffers from long-term prestress losses, which seriously affect the safety performance of the tanks. In this paper, a large LNG storage tank in China was taken as the research object. By using the age-adjusted effective modulus method and the relevant models in the design code of concrete structure, the multiple models were established by using the ABAQUS finite element software to simulate the prestress loss caused by shrinkage creep, stress relaxation and coupling effect. Then, the influence law of the interaction between shrinkage creep and stress relaxation on the long-term prestress loss was analyzed. Finally, the influence of two-way prestress on the long-term prestress loss was discussed. And the following research results were obtained. First, the ultimate(50 years) maximum of long-term losses in circumferential and vertical prestressing tendons reach 10.97% and 17.02% of the tension control stress, respectively. Second, the losses in circumferential and vertical prestressing tendons under the coupling effect of shrinkage creep and stress relaxation are 83.59% and 86.33% of the algebraic sum of shrinkage creep loss and stress relaxation loss. Third, the interaction reduction coefficient is proposed, and it reaches the minimum value when the shrinkage creep loss and the stress relaxation loss are close. Fourth, the effect of vertical prestress on the long-term prestress loss in circumferential prestressing tendons is obvious. In conclusion, the research results are crucial to the design safety of concrete wall of large LNG tanks.
引文
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[7]中华人民共和国交通部.公路钢筋混凝土及预应力混凝土桥涵设计规范:JTG D62-2004[S].北京:人民交通出版社,2004.Ministry of Transport of the PRC.Code for design of highway reinforced concrete and prestressed concrete bridge and culverts:JTG D62-2004[S].Beijing:China Communications Press,2004.
[8]British Standards Institution.Eurocode 2:Design of concrete structures.Part 2:Concrete bridges--design and detailing rules:EN 1992-2:2005[S].London:British Standards Institution,2005.
[9]American Association of State Highway and Transportations.Bridge design specifications:AASHTO-L-RFD[S].Washington,DC:AASHTO,2004.
[10]廖开星,李毅,孔祥龙,汤志杰,遆文新.核电站安全壳混凝土结构长期预应力损失模型初步研究[J].混凝土,2015,37(5):140-144.Liao Kaixing,Li Yi,Kong Xianglong,Tang Zhijie&Ti Wenxin.Primary research on nuclear power station containment concrete structure long-term prestress forecasting model[J].Concrete,2015,37(5):140-144.
[11]Anderson P.Thirty years of measured prestress at Swedish nuclear reactor containments[J].Nuclear Engineering&Design,2005,235(21):2323-2336.
[12]泮忠元,王社良.大体积混凝土(核电站安全壳)预应力损失分析[J].水利与建筑工程学报,2009,7(1):78-84.Pan Zhongyuan&Wang Sheliang.Analysis on prestressing losses of mass concrete(safety shell of nuclear power plant)[J].Journal of Water Resources and Architectural Engineering,2009,7(1):78-84.
[13]林树潮.LNG储罐变曲率摩擦隔震与罐壳结构预应力施工仿真[D].北京:北京工业大学,2016.Lin Shuchao.VCFPB base isolation and prestressed tendon construction research for LNG storage tanks[D].Beijing:Beijing University of Technology,2016.
[14]Hsuan TH&Lin JX.Ultimate analysis of PWR prestressed concrete containment under long-term prestressing loss[J].Annals of Nuclear Energy,2016,87(1):500-510.
[15]周履,陈永春.收缩徐变[M].北京:中国铁道出版社,1994.Zhou Lü&Chen Yongchun.Shrinkage and creep[M].Beijing:China Railway Publishing House,1994.
[16]高嵩.静力及风荷载作用下LNG储罐混凝土外罐手受力性能分析[D].哈尔滨:哈尔滨工业大学,2014.Gao Song.Mechanical behavioral of LNG concrete of containment outer tank under static and wind loads[D].Harbin:Harbin Institute of Technology,2014.
[17]傅作新.工程徐变力学[M].北京:中国水利电力出版社,1995.Fu Zuoxin.Engineering creep mechanics[M].Beijing:China Water Power Press,1995.
[18]Bazant ZP.Prediction of concrete creep effects using age adjusted effective modulus method[J].ACI Journal,1972,69(4):212-217.
[19]卓旬,梅明荣.混凝土徐变计算理论和方法综述[J].水利与建筑工程学报,2012,10(2):14-19.Zhuo Xun&Mei Mingrong.Summarized account for calculation theory and methods of concrete creep[J].Journal of Water Resources and Architectural Engineering,2012,10(2):14-19.
[20]张超.ABAUQS在LNG储罐设计与分析中的应用[M].北京:北京理工大学出版社,2015.Zhang Chao.Application of ABAQUS in LNG storage tank design and analysis[M].Beijing:Beijing Institute of Technology Press,2015.
[2]程旭东,彭文山,孙连方,李潇南,尹铸华.热应力作用下LNG储罐外罐裂缝及失效时间分析[J].天然气工业,2015,35(3):819-823.Cheng Xudong,Peng Wenshan,Sun Lianfang,Li Xiaonan&Yin Zhuhua.Analysis of the fracture pattern and failure time of LNGouter tanks under the action of thermal load[J].Natural Gas Industry,2015,35(3):819-823.
[3]程旭东,朱兴吉,胡晶晶,于晓玮.LNG储罐预应力混凝土外罐应力分布与裂缝形态[J].油气储运,2011,30(10):746-749.Cheng Xudong,Zhu Xingji,Hu Jingjing&Yu Xiaowei.Stress distribution and crack form of the prestressed concrete outer tank of LNG tank[J].Oil&Gas Storage and Transportation,2011,30(10):746-749.
[4]韩明一.大型LNG储罐外罐预应力损失研究[D].青岛:中国石油大学(华东),2015.Han Mingyi.Loss of prestress analyses on external walls of LNGstorage tanks[D].Qingdao:China University of Petroleum(East China),2015.
[5]中华人民共和国住房和城乡建设部,中华人民共和国国家质量监督检查检疫总局.混凝土结构设计规范:GB 50010-2010[S].北京:中国建筑工业出版社,2010.Ministry of Housing and Urban-Rural Development of the PRC&General Administration of Quality Supervision,Inspection and Quarantine of the PRC.Code for design of concrete structure:GB50010-2010[D].Beijing:China Architecture&Building Press,2010.
[6]中华人民共和国铁道部.铁路桥涵钢筋混凝土和预应力混凝土结构设计规范:TB 10002.3-2005[S].北京:中国铁道出版社,2005.Ministry of Railways of the PRC.Code for design on reinforced and prestressed concrete structure of railway bridge and culvert:TB 10002.3-2005[S].Beijing:China Railway Publishing House,2005.
[7]中华人民共和国交通部.公路钢筋混凝土及预应力混凝土桥涵设计规范:JTG D62-2004[S].北京:人民交通出版社,2004.Ministry of Transport of the PRC.Code for design of highway reinforced concrete and prestressed concrete bridge and culverts:JTG D62-2004[S].Beijing:China Communications Press,2004.
[8]British Standards Institution.Eurocode 2:Design of concrete structures.Part 2:Concrete bridges--design and detailing rules:EN 1992-2:2005[S].London:British Standards Institution,2005.
[9]American Association of State Highway and Transportations.Bridge design specifications:AASHTO-L-RFD[S].Washington,DC:AASHTO,2004.
[10]廖开星,李毅,孔祥龙,汤志杰,遆文新.核电站安全壳混凝土结构长期预应力损失模型初步研究[J].混凝土,2015,37(5):140-144.Liao Kaixing,Li Yi,Kong Xianglong,Tang Zhijie&Ti Wenxin.Primary research on nuclear power station containment concrete structure long-term prestress forecasting model[J].Concrete,2015,37(5):140-144.
[11]Anderson P.Thirty years of measured prestress at Swedish nuclear reactor containments[J].Nuclear Engineering&Design,2005,235(21):2323-2336.
[12]泮忠元,王社良.大体积混凝土(核电站安全壳)预应力损失分析[J].水利与建筑工程学报,2009,7(1):78-84.Pan Zhongyuan&Wang Sheliang.Analysis on prestressing losses of mass concrete(safety shell of nuclear power plant)[J].Journal of Water Resources and Architectural Engineering,2009,7(1):78-84.
[13]林树潮.LNG储罐变曲率摩擦隔震与罐壳结构预应力施工仿真[D].北京:北京工业大学,2016.Lin Shuchao.VCFPB base isolation and prestressed tendon construction research for LNG storage tanks[D].Beijing:Beijing University of Technology,2016.
[14]Hsuan TH&Lin JX.Ultimate analysis of PWR prestressed concrete containment under long-term prestressing loss[J].Annals of Nuclear Energy,2016,87(1):500-510.
[15]周履,陈永春.收缩徐变[M].北京:中国铁道出版社,1994.Zhou Lü&Chen Yongchun.Shrinkage and creep[M].Beijing:China Railway Publishing House,1994.
[16]高嵩.静力及风荷载作用下LNG储罐混凝土外罐手受力性能分析[D].哈尔滨:哈尔滨工业大学,2014.Gao Song.Mechanical behavioral of LNG concrete of containment outer tank under static and wind loads[D].Harbin:Harbin Institute of Technology,2014.
[17]傅作新.工程徐变力学[M].北京:中国水利电力出版社,1995.Fu Zuoxin.Engineering creep mechanics[M].Beijing:China Water Power Press,1995.
[18]Bazant ZP.Prediction of concrete creep effects using age adjusted effective modulus method[J].ACI Journal,1972,69(4):212-217.
[19]卓旬,梅明荣.混凝土徐变计算理论和方法综述[J].水利与建筑工程学报,2012,10(2):14-19.Zhuo Xun&Mei Mingrong.Summarized account for calculation theory and methods of concrete creep[J].Journal of Water Resources and Architectural Engineering,2012,10(2):14-19.
[20]张超.ABAUQS在LNG储罐设计与分析中的应用[M].北京:北京理工大学出版社,2015.Zhang Chao.Application of ABAQUS in LNG storage tank design and analysis[M].Beijing:Beijing Institute of Technology Press,2015.