桩基础抗震性能的简易评价方法
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摘要
桩基础的抗震性能可从承载力和变形两方面来评价。承载力可考虑地震时作用于结构上的荷载组合,多采用拟静力法进行分析,不同因素变异的影响可用概率分析或可靠度方法予以考虑。变形分析多为按承载力设计之后的校核,其中地震力和土体参数以及地质条件等因素影响可分别加以评估。本文着重阐明基于一维波动方程和概率分析的桩基抗震性能实用分析方法,并以桥梁桩基础为例进行讨论,其中考虑的关键因素为设计地震加速度、测站记录、基桩尺寸及其配筋率。研究表明,当土层液化可忽略时最大弯矩会发生在桩顶,故增加桩顶延性可有效提升桩基础的抗震性能。
Performance based design for pile foundations can be analyzed on bearing capacities and deformations.The foundation capacities are often computed knowing the superstructural loads and their combinations.The design needs to consider ordinary and special conditions.Conventional calculation methods or other reliable methods can be adopted.Influence factors are assessed by probability and/or reliability analyses to match the PBD requirements.On the other hand,foundation deformations can be analyzed further.The effects of seismic forces,soil parameters and geological structure could be evaluated independently.This paper introduces the seismic PBD analysis on piles using one-dimensional wave equation analysis and the so called PBEE analysis.A case study is discussed on the bridge pile foundations.The key issues in the analysis are design PGA,accelerogram,pile dimensions and the amount of steel bars in use.It is found that if the soil liquefaction influence could be negligible,then the maximum bending moment would occur at pile head,in which to increase the ductility of the pile at the pile head will help the seismic performance of the piles.
Performance based design for pile foundations can be analyzed on bearing capacities and deformations.The foundation capacities are often computed knowing the superstructural loads and their combinations.The design needs to consider ordinary and special conditions.Conventional calculation methods or other reliable methods can be adopted.Influence factors are assessed by probability and/or reliability analyses to match the PBD requirements.On the other hand,foundation deformations can be analyzed further.The effects of seismic forces,soil parameters and geological structure could be evaluated independently.This paper introduces the seismic PBD analysis on piles using one-dimensional wave equation analysis and the so called PBEE analysis.A case study is discussed on the bridge pile foundations.The key issues in the analysis are design PGA,accelerogram,pile dimensions and the amount of steel bars in use.It is found that if the soil liquefaction influence could be negligible,then the maximum bending moment would occur at pile head,in which to increase the ductility of the pile at the pile head will help the seismic performance of the piles.
引文
[1]Poulos H G,Davis E H.Pile Foundation Analysis and Design[M].New York:Wiley,1980.
[2]Randolph M F.Design Methods for Pile Groups and PiledRafts[A]//Proceedings of XIII ICSMFE[C].New Delhi:[s.n.],1994:61-82.
[3]Poulos H G.Piled Raft Foundations:Design and Applications[J].Geotechnique,2001,51(2):95-113.
[4]Reese L C,Van Impe W F.Single Piles and Pile Groups underLateral Loading[M].Rotterdam,The Netherlands:[s.n.],2001.
[5]Boulanger R W,Curras C J,Kutter B L,et al.Seismic Soil-pile-structure Interaction Experiments and Analyses[J].Jour-nal of Geotechnical and Geoenvironmental Engineering,1999,125(9):750-759.
[6]Chang D W,Lin B S.Wave Equation Analyses on Seismic Re-sponses of Grouped Piles[A]∥Proceedings of the 12th AsianRegional Conference on Soil Mechanics and Geotechnical Engi-neering[C].Singapore:[s.n.],2003:581-586.
[7]Chang D W,Lin B S.EQWEAP—A Simplified Procedure toAnalyze Dynamic Pile-soil Interaction with Soil LiquefactionConcerns[A]∥Proceedings of the 2nd Taiwan-Japan JointWorkshop on Geotechnical Hazards from Large Earthquakeand Heavy Rainfall[C].Japan:[s.n.],2006:155-162.
[8]Japan Road Association Specification for Highway Bridges,part IV:Underground Structure Design[S].Japan:[s.n.],1990.
[9]Finn W D L,Lee K W,Martin G R.An Effective Stress Mod-el for Liquefaction[J].Journal of the Geotechnical EngineeringDivision,1977,103(6):657-692.
[10]Seed H B,Idriss I M.Ground Motions and Soil LiquefactionDuring Earthquakes[M].California:Earthquake EngineeringResearch Institute,1982.
[11]张建民.水平地基液化后大变形对桩基础的影响[J].建筑结构学报,2001,22(5):75-78.ZHANG Jian-min.Effect of Large Horizontal Post-liquefac-tion Deformation of Level Ground on Pile Foundation[J].Journal of Building Structures,2001,22(5):75-78.
[12]张建民,王刚.考虑地基液化后大变形的桩-土动力相互作用分析[J].清华大学学报(自然科学版),2004,44(3):429-432.ZHANG Jian-min,WANG Gang.Pile-soil Dynamic Interac-tion Analysis Considering Large Post-liquefaction Ground De-formation[J].Journal of Tsinghua University(Science andTechnology),2004,44(3):429-432.
[13]Kramer S L.Performance-based Earthquake Engineering:Opportunities and Implications for Geotechnical EngineeringPractice[M].Geotechnical Earthquake Engineering and SoilDynamics.ASCE Geotechnical Special Publication 181,2008.
[14]Shin H S.Numerical Modeling of a Bridge System and ItsApplication for Performance-Based Earthquake Engineering[D].Washington:University of Washington,2007.
[15]Bradley B,Cubrinovski M,Dhakal R.Performance-basedSeismic Response of Pile Foundations[M].GeotechnicalEarthquake Engineering and Soil Dynamics.ASCE Geotech-nical Special Publication 181,2008.
[16]Chang D W,Lin B S,Cheng S H.Lateral Load Distributionson Grouped Piles from Dynamic Pile-to-pile Interaction Fac-tors[J].International Journal for Numerical and AnalyticalMethods in Geomechanics,2009,33(2):173-191.
[17]Chang D W,Yang T Y,Yang C L.Seismic Performance ofPiles from PBEE and EQWEAP Analyses[J].GeotechnicalEngineering,2010,41(2):1-8.
[18]Dobry R,Gazetas G.Simple Method for Dynamic Stiffnessand Damping of Floating Pile Groups[J].Geotechnique,1988,38(4):557-74.
[19]Byrne P M.A Cyclic Shear-volume Coupling and Pore Pres-sure Model for Sand[A]//Proceedings of the 2nd Interna-tional Conference on Recent Advances in Geotechnical Earth-quake and Soil Dynamics[C].St.Louis:[s.n.],1991:47-56.
[20]Skempton A W.Standard Penetration Test Procedures andthe Effects in Sands of Overburden Pressure,Relative Densi-ty,Particle Size,Aging and Overconsolidation[J].Geotech-nique,1986,36(3):425-447.
[21]Johnson S M,Kavanaugh T C.The Design of Foundations forBuildings[M].New York:McGraw Hill,1968:393.
[22]Chang D W,Yeh S H.Time-Domain Wave Equation Analysisof Single Piles Utilizing Transformed Radiation Damping[J].Soils and Foundations,1999,39(2):31-44.
[23]Chang D W,Rosset J M,Wen C H.A Time-Domain ViscousDamping Model Based on Frequency-Depend Damping Ratios[J].Soil Dynamic and Earthquake Engineering,2000,19(8):551-558.
[24]Kunnath S K,Reinhom A M.Inelastic Three-dimensionalResponse Analysis of Reinforced Concrete Building Structure(IDARC-3D)Part I—Modeling[R].Buffalo,New York:Technical Report NCEER-89-0011,National Center forEarthquake Engineering Research,State University at NewYork,1989.
[25]Tokimatsu K,Asaka Y.Effects of Liquefaction-inducedGround Displacement on Pile Performance in the 1995Hyogoken-Nambu Earthquake[J].Soils and Foundations,(Special Issue),1998:163-78.
[26]Zhang J-M,Shamoto Y,Tokimatsu K.Evaluation of EarthPressure under Any Lateral Deformation[J].Soils and Foun-dations,1998,38(1):15-33.
[27]Zhang J-M,Shamoto Y,Tokimatsu K.Seismic Earth Pres-sure Theory for Retaining Walls under Any Lateral Displace-ment[J].Soils and Foundations,1998,38(2):143-63.
[28]Chang D W,Cheng S H,Wang Y L.One-Dimensional WaveEquation Analyses for Pile Responses to Horizontal GroundMotions of Earthquake[J].Soils and Foundations(under re-view),2012.
[29]Jalayer F.Direct Probability Seismic Analysis:ImplementingNon-linear Dynamic Assessments[D].California:StanfordUniversity,2003.
[30]郑锦桐.台湾地区地震危害度的不确定性分析与参数拆解[D].桃园:中央大学,2002.Cheng C T.Uncertainty Analysis and Deaggregation of Seis-mic Hazard in Taiwan[D].Taoyuan:National Central Uni-versity,2002.
[31]吴伟特.台北盆地地盘分区土壤之工程特性[J].地工技术杂志,1988,22:5-27.Wu W T.Geotechnical Engineering Characteristics of Soils inrelation to Horizontal Zoning in Taipei Basin[J].Sino-Geotechnics,1988,22:5-27.
[32]陈正兴,杨鹤雄,黄俊鸿,等.交通结构物基础耐震性能设计之研议[J].地工技术,2006,109:73-82.Chen C H,Yang H H,Huang C H.et al.Study on SeismicPerformance Design for Foundations of Transportation Sys-tem[J].Sino-Geotechnics,2006,109:73-82.
[2]Randolph M F.Design Methods for Pile Groups and PiledRafts[A]//Proceedings of XIII ICSMFE[C].New Delhi:[s.n.],1994:61-82.
[3]Poulos H G.Piled Raft Foundations:Design and Applications[J].Geotechnique,2001,51(2):95-113.
[4]Reese L C,Van Impe W F.Single Piles and Pile Groups underLateral Loading[M].Rotterdam,The Netherlands:[s.n.],2001.
[5]Boulanger R W,Curras C J,Kutter B L,et al.Seismic Soil-pile-structure Interaction Experiments and Analyses[J].Jour-nal of Geotechnical and Geoenvironmental Engineering,1999,125(9):750-759.
[6]Chang D W,Lin B S.Wave Equation Analyses on Seismic Re-sponses of Grouped Piles[A]∥Proceedings of the 12th AsianRegional Conference on Soil Mechanics and Geotechnical Engi-neering[C].Singapore:[s.n.],2003:581-586.
[7]Chang D W,Lin B S.EQWEAP—A Simplified Procedure toAnalyze Dynamic Pile-soil Interaction with Soil LiquefactionConcerns[A]∥Proceedings of the 2nd Taiwan-Japan JointWorkshop on Geotechnical Hazards from Large Earthquakeand Heavy Rainfall[C].Japan:[s.n.],2006:155-162.
[8]Japan Road Association Specification for Highway Bridges,part IV:Underground Structure Design[S].Japan:[s.n.],1990.
[9]Finn W D L,Lee K W,Martin G R.An Effective Stress Mod-el for Liquefaction[J].Journal of the Geotechnical EngineeringDivision,1977,103(6):657-692.
[10]Seed H B,Idriss I M.Ground Motions and Soil LiquefactionDuring Earthquakes[M].California:Earthquake EngineeringResearch Institute,1982.
[11]张建民.水平地基液化后大变形对桩基础的影响[J].建筑结构学报,2001,22(5):75-78.ZHANG Jian-min.Effect of Large Horizontal Post-liquefac-tion Deformation of Level Ground on Pile Foundation[J].Journal of Building Structures,2001,22(5):75-78.
[12]张建民,王刚.考虑地基液化后大变形的桩-土动力相互作用分析[J].清华大学学报(自然科学版),2004,44(3):429-432.ZHANG Jian-min,WANG Gang.Pile-soil Dynamic Interac-tion Analysis Considering Large Post-liquefaction Ground De-formation[J].Journal of Tsinghua University(Science andTechnology),2004,44(3):429-432.
[13]Kramer S L.Performance-based Earthquake Engineering:Opportunities and Implications for Geotechnical EngineeringPractice[M].Geotechnical Earthquake Engineering and SoilDynamics.ASCE Geotechnical Special Publication 181,2008.
[14]Shin H S.Numerical Modeling of a Bridge System and ItsApplication for Performance-Based Earthquake Engineering[D].Washington:University of Washington,2007.
[15]Bradley B,Cubrinovski M,Dhakal R.Performance-basedSeismic Response of Pile Foundations[M].GeotechnicalEarthquake Engineering and Soil Dynamics.ASCE Geotech-nical Special Publication 181,2008.
[16]Chang D W,Lin B S,Cheng S H.Lateral Load Distributionson Grouped Piles from Dynamic Pile-to-pile Interaction Fac-tors[J].International Journal for Numerical and AnalyticalMethods in Geomechanics,2009,33(2):173-191.
[17]Chang D W,Yang T Y,Yang C L.Seismic Performance ofPiles from PBEE and EQWEAP Analyses[J].GeotechnicalEngineering,2010,41(2):1-8.
[18]Dobry R,Gazetas G.Simple Method for Dynamic Stiffnessand Damping of Floating Pile Groups[J].Geotechnique,1988,38(4):557-74.
[19]Byrne P M.A Cyclic Shear-volume Coupling and Pore Pres-sure Model for Sand[A]//Proceedings of the 2nd Interna-tional Conference on Recent Advances in Geotechnical Earth-quake and Soil Dynamics[C].St.Louis:[s.n.],1991:47-56.
[20]Skempton A W.Standard Penetration Test Procedures andthe Effects in Sands of Overburden Pressure,Relative Densi-ty,Particle Size,Aging and Overconsolidation[J].Geotech-nique,1986,36(3):425-447.
[21]Johnson S M,Kavanaugh T C.The Design of Foundations forBuildings[M].New York:McGraw Hill,1968:393.
[22]Chang D W,Yeh S H.Time-Domain Wave Equation Analysisof Single Piles Utilizing Transformed Radiation Damping[J].Soils and Foundations,1999,39(2):31-44.
[23]Chang D W,Rosset J M,Wen C H.A Time-Domain ViscousDamping Model Based on Frequency-Depend Damping Ratios[J].Soil Dynamic and Earthquake Engineering,2000,19(8):551-558.
[24]Kunnath S K,Reinhom A M.Inelastic Three-dimensionalResponse Analysis of Reinforced Concrete Building Structure(IDARC-3D)Part I—Modeling[R].Buffalo,New York:Technical Report NCEER-89-0011,National Center forEarthquake Engineering Research,State University at NewYork,1989.
[25]Tokimatsu K,Asaka Y.Effects of Liquefaction-inducedGround Displacement on Pile Performance in the 1995Hyogoken-Nambu Earthquake[J].Soils and Foundations,(Special Issue),1998:163-78.
[26]Zhang J-M,Shamoto Y,Tokimatsu K.Evaluation of EarthPressure under Any Lateral Deformation[J].Soils and Foun-dations,1998,38(1):15-33.
[27]Zhang J-M,Shamoto Y,Tokimatsu K.Seismic Earth Pres-sure Theory for Retaining Walls under Any Lateral Displace-ment[J].Soils and Foundations,1998,38(2):143-63.
[28]Chang D W,Cheng S H,Wang Y L.One-Dimensional WaveEquation Analyses for Pile Responses to Horizontal GroundMotions of Earthquake[J].Soils and Foundations(under re-view),2012.
[29]Jalayer F.Direct Probability Seismic Analysis:ImplementingNon-linear Dynamic Assessments[D].California:StanfordUniversity,2003.
[30]郑锦桐.台湾地区地震危害度的不确定性分析与参数拆解[D].桃园:中央大学,2002.Cheng C T.Uncertainty Analysis and Deaggregation of Seis-mic Hazard in Taiwan[D].Taoyuan:National Central Uni-versity,2002.
[31]吴伟特.台北盆地地盘分区土壤之工程特性[J].地工技术杂志,1988,22:5-27.Wu W T.Geotechnical Engineering Characteristics of Soils inrelation to Horizontal Zoning in Taipei Basin[J].Sino-Geotechnics,1988,22:5-27.
[32]陈正兴,杨鹤雄,黄俊鸿,等.交通结构物基础耐震性能设计之研议[J].地工技术,2006,109:73-82.Chen C H,Yang H H,Huang C H.et al.Study on SeismicPerformance Design for Foundations of Transportation Sys-tem[J].Sino-Geotechnics,2006,109:73-82.
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