基于Pushover分析的群桩基础抗震性能分析方法
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摘要
把桥梁群桩基础作为一个整体构件,基于Pushover分析,提出群桩基础的抗震性能分析方法,建立承台底荷载模型和非线性群桩基础结构模型(弹塑性桩身模型、非线性边界条件),并提出衡量群桩基础抗震性能的双指标(位移延性系数和抗力增大系数)。根据这一方法,选取一个实际的桥梁群桩基础作为背景建立群桩基础的非线性结构模型以及一系列的荷载工况,计算各种荷载水平对应的群桩基础推倒曲线,并采用本文建议的位移延性系数和抗力增大系数进行抗震性能评价。结果表明:承台底的轴力和弯矩水平虽然对群桩基础的屈服状态和极限状态对应的水平力和位移有显著影响,但对整体抗震性能指标影响很小;在各种荷载水平下,群桩基础的位移延性系数和抗力增大系数都较小。
Treating a group pile foundation as one entity component,an approach of seismic performance analysis for group pile foundations was developed,based on Pushover analysis. A load model and a nonlinear structure model (inelastic pile model and nonlinear boundary condition) for group pile foundations were established,and two specific seismic performance indices,displacement ductility factor and resistance amplification factor,were proposed. The seismic performance analysis of a real group pile foundation was conducted. Based on the nonlinear structural model of the group pile foundation,a series of load cases were developed,the corresponding Pushover curves,the displacement ductility factors,and the resistance amplification factors were calculated. The results indicated that,the axial force and bending moment at the bottom of the pile cap slightly influenced the seismic performance index,while their effects on the lateral force and displacement in yield and ultimate limit state were significant. The displacement ductility factors and resistance amplification factors were quite small under all types of loadings.
Treating a group pile foundation as one entity component,an approach of seismic performance analysis for group pile foundations was developed,based on Pushover analysis. A load model and a nonlinear structure model (inelastic pile model and nonlinear boundary condition) for group pile foundations were established,and two specific seismic performance indices,displacement ductility factor and resistance amplification factor,were proposed. The seismic performance analysis of a real group pile foundation was conducted. Based on the nonlinear structural model of the group pile foundation,a series of load cases were developed,the corresponding Pushover curves,the displacement ductility factors,and the resistance amplification factors were calculated. The results indicated that,the axial force and bending moment at the bottom of the pile cap slightly influenced the seismic performance index,while their effects on the lateral force and displacement in yield and ultimate limit state were significant. The displacement ductility factors and resistance amplification factors were quite small under all types of loadings.
引文
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[8]王成华,孙冬梅.横向受荷桩的p-y曲线研究与应用述评[J].中国海湾建设,2005,(2):1-4(Wang Chenghua,Sun Dongmei.Review of the researches and applications ofp-ycurves for laterally loaded piles[J].China Harbour Engineering,2005,(2):1-4(in Chinese))
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[10]鲁传安.桥梁群桩基础的抗震性能研究[D].上海:同济大学,2008(Lu Chuan′an.Seismic performance analysis of bridge group pile foundation[D].Shanghai:Tongji University,2008(in Chinese))
[2]陈跃庆,吕西林.几次大地震中地基基础震害的启示[J].工程抗震,2001,(2):8-15(Chen Yueqing,Lu Xilin.Lessons learned from damages of soils and foundations during several strong earthquakes[J].Earthquake Resistant Engineering,2001,(2):8-15(in Chinese))
[3]Freeman S A,Nicoletti J P,Tyrell J V.Evaluations of existing buildings for seismic risk-A case study of puget sound naval shipyard[C]//Proceedings of1st U.S.National Conference on Earthquake Engineering.California:Berkeley,1975:113-122
[4]Krawinkler H,Seneviratna G D PK.Pros and cons of a pushover analysis of seismic performance evaluation[J].Engineering Structures,1998,20(4/6):452-464
[5]卓卫东.桥梁延性抗震设计研究[D].上海:同济大学,2000(Zhuo Weidong.Seismic design of ductile bridges[D],Shanghai:Tongji University,2000(in Chinese))
[6]Mander J B,Priestley M J N,Park R..Observed stress-strain behavior of confined concrete[J].Journal of Structural Engineering,ASCE,114(8):1827-1849
[7]Spacone E,Filippou F C,Taucer F F.Fibre beam-column model for non-linear analysis of R/C frames:Part I.Formulation[J].Earthquake Engineering and Structural Dynamics,1996,25(7):711-725
[8]王成华,孙冬梅.横向受荷桩的p-y曲线研究与应用述评[J].中国海湾建设,2005,(2):1-4(Wang Chenghua,Sun Dongmei.Review of the researches and applications ofp-ycurves for laterally loaded piles[J].China Harbour Engineering,2005,(2):1-4(in Chinese))
[9]黎杰仑.冲刷桩基承受侧向载重之变位分析[D].台湾:国立成功大学,1994(Li Chieh Lun.Displacement analysis of scoured pile foundation under lateral loading[D].Taiwan:National Chenggong University,1994(in Chinese))
[10]鲁传安.桥梁群桩基础的抗震性能研究[D].上海:同济大学,2008(Lu Chuan′an.Seismic performance analysis of bridge group pile foundation[D].Shanghai:Tongji University,2008(in Chinese))
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