斜拉弯桥有限元分析模型的对比研究
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摘要
目的对比研究某斜拉弯桥不同的有限元分析模型,给出该桥合理的有限元分析模型,为该桥的长期监测和安全评估提供基础.方法分别采用板壳单元、即考虑弯曲又考虑剪切变形的梁格单元以及考虑弯曲但不考虑剪切变形的梁格单元处理某斜拉弯桥的钢箱梁.对比分析3种不同有限元分析模型的计算结果,确定出该斜拉弯桥合理的有限元模型.结果桥面钢箱梁分别采用3种有限元分析模型计算时,不同模型给出的下游侧拉索应力值差别较大,上游侧拉索及背索的应力值差别较小.采用即考虑弯曲又考虑剪切变形的梁格单元与采用板壳单元模型时,计算给出的主塔弯矩值以及桥面下游纵向腹板处上顶板和下底板的等效应力值较为接近.结论钢箱梁采用即考虑弯曲又考虑剪切变形的梁格单元与钢箱梁采用板壳单元模型,都可以作为该桥合理的有限元分析模型.当钢箱梁横隔板间距不远大于梁高时,不能忽略梁剪切变形的影响,此时采用考虑弯曲但不考虑剪切变形的梁格单元模拟钢箱梁不合理.
The establishment of the reasonable finite element model is studied for a cable-stayed curved bridge in order to provide the basis of long term monitoring and safety evaluation for the bridge.The shell element and beam-gird element are used to simulate steel box girder of the bridge.Two kinds of beam-gird elements are used for the finite element model respectively.One(Timoshenko beam)takes both the bending deflection and shear deflection into consideration.The other(Euler-Bernoulli beam)considers the bending deflection but neglects the shear deflection.The states of stresses are analyzed for the main members of the bridge under the dead weight for the three models of this bridge respectively.The reasonable finite element model for this bridge can be given by comparing the calculation results obtained from the three different finite element models.The corresponding stress values of downstream cable given by the three different models are quite different,but the corresponding upstream cable and back-stays stress values are close to one another.The bending moments of the main tower and the equivalent stresses of the top and bottom wings just at the outer downstream steel web,obtained from the model of Timoshenko beam element,are closer to those of the shell element model rather than the Euler-Bernoulli beam model.The conclusions are that the shell element model and Timoshenko beam element model are the reasonable models for simulating steel box girder of the bridge.The Euler-Bernoulli beam model is unreasonable because the distances between the diaphragms are not so much bigger than the height of the steel box girder that the effect of shear deflection can not be neglected.
The establishment of the reasonable finite element model is studied for a cable-stayed curved bridge in order to provide the basis of long term monitoring and safety evaluation for the bridge.The shell element and beam-gird element are used to simulate steel box girder of the bridge.Two kinds of beam-gird elements are used for the finite element model respectively.One(Timoshenko beam)takes both the bending deflection and shear deflection into consideration.The other(Euler-Bernoulli beam)considers the bending deflection but neglects the shear deflection.The states of stresses are analyzed for the main members of the bridge under the dead weight for the three models of this bridge respectively.The reasonable finite element model for this bridge can be given by comparing the calculation results obtained from the three different finite element models.The corresponding stress values of downstream cable given by the three different models are quite different,but the corresponding upstream cable and back-stays stress values are close to one another.The bending moments of the main tower and the equivalent stresses of the top and bottom wings just at the outer downstream steel web,obtained from the model of Timoshenko beam element,are closer to those of the shell element model rather than the Euler-Bernoulli beam model.The conclusions are that the shell element model and Timoshenko beam element model are the reasonable models for simulating steel box girder of the bridge.The Euler-Bernoulli beam model is unreasonable because the distances between the diaphragms are not so much bigger than the height of the steel box girder that the effect of shear deflection can not be neglected.
引文
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[12]Batoz J L,Bathe K J,Ho L W.A study of three-node triangular plate bending elements[J].Interna-tional Journal for Numerical Methods in Engineer-ing,1980,15(12):1771-1812.
[13]Cook R D.Concepts and applications of finite ele-ment analysis[M].Toronto:John Wiley and Sons,1974.
[2]Zong Zhouhong,Jaishi B,Ge Jiping,et al.Dynamic analysis of a half-through concrete-filled steel tu-bular arch bridge[J].Engineering Structures,2005,27:3-15.
[3]孙正华,李兆霞.润扬斜拉桥有限元模拟及模态分析[J].地震工程与工程震动,2006,26(2):25-32.(Sun Zhenghua,Li Zhaoxia.Finite element modeling and modal analysis of Runyang Cable-stayed Bridge[J].Earthquake Engineering and Engineering Vibration,2006,26(2):25-32.)
[4]Anun P,Worsak K.Health monitoring of highway bridges based on a Global Flexibility Index[J].En-gineering Structures,2005,27:1385-1391.
[5]Stephen G A,Brownjohn J M W,Taylor C A.Meas-urements of static and dynamic displacement from visual monitoring of the Humber Bridge[J].Engi-neering Structures,1993,15(3):197-208.
[6]Fryba L,Pirner M.Load tests and modal analysis of bridges.Engineering Structures,2001,23:102-109.
[7]孙颖,卓卫东.曲线箱梁桥动力计算模型与动力特性参数分析[J].福建建筑,2007(12):101-104.(Sun Ying,Zhuo Weidong.FEM-model and pa-rameter-analysis on dynamic characteristics for curved box beam bridges[J].Fujian Architecture&Construction,2007(12):101-104.)
[8]周勇军,赵小星.弯钢箱梁桥的动力分析及模态试验[J].郑州大学学报:工学版,2005,26(4):20-24.(Zhou Yongjun,Zhao Xiaoxing.Dynamic analysis and modal test of a curved steel box girder[J].Jour-nal of Zhengzhou University:Engineering Science,2005,26(4):20-24.)
[9]彭大文,袁燕,江见虹.厦门海沧大桥西航道桥的动力特性研究[J].福州大学学报:自然科学版,1999,27(3):11-14.(Peng Dawen,Yuan Yan,Jiang Jianhong.Dynamic behavior analysis of western approach bridge of Xia-men Haicang Bridge[J].Journal of Fuzhou Universi-ty:Natural Science,1999,27(3):11-14.)
[10]张发春,杨昌正.梁格法在弯箱梁桥上的分析及应用[J].重庆交通大学学报:自然科学版,2008,27(1):13-16.(Zhang Fachun,Yang Changzheng.Analysis and ap-plication of grillage method to curved girder bridge[J].Journal of Chongqing Jiaotong University:Nat-ural Science,2008,27(1):13-16.)
[11]刘铁林,王刚,刘博.吊杆损伤下钢管混凝土拱桥的超载研究[J].沈阳建筑大学学报:自然科学版,2010,26(1):86-91.(Liu Tielin,Wang Gang,Liu Bo.Research on over-loading of concrete-filled steel tubular arch bridge with suspender damage[J].Journal of Shenyang Jianzhu University:Natural Science,2010,26(1):86-91.)
[12]Batoz J L,Bathe K J,Ho L W.A study of three-node triangular plate bending elements[J].Interna-tional Journal for Numerical Methods in Engineer-ing,1980,15(12):1771-1812.
[13]Cook R D.Concepts and applications of finite ele-ment analysis[M].Toronto:John Wiley and Sons,1974.
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