基于桥梁多灾害设计的典型桥梁实证分析
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摘要
目前美国的桥梁设计规范在考虑重力荷载和卡车荷载组合时分别采用1.25和1.75的系数,但是当考虑地震荷载作用时,取地震系数1.0,一般不考虑卡车荷载,特殊情况需要考虑时卡车荷载系数为0.5。这说明地震与卡车组合时候,其概率理论的不完备性。基于此,参考文献[16,17]不仅给出了地震和重卡车作用下的组合理论,还给出其共同作用下荷载系数的计算方法。本文的主要目的是用一个典型桥梁实例对求解的荷载系数进行检验。通过有限元软件对采用新的荷载系数的桥墩截面配筋进行重新设计,然后,对新桥进行地震作用下的pushover分析,并与现行LRFD规范的规定值进行对比。结果表明,新的荷载系数能够保证桥梁结构的安全,可以按其设计。
The current Guide Specification for LRFD Seismic Bridge Design uses 1. 25 for dead load and 1. 75 for truck load,but 1. 0 for earthquake alone or 1. 0 earthquake and 0. 5 times truck load for special conditions when considering earthquake effects,which indicates that the probabilistic theory for earthquake and heavy truck load combination is not complete. Based on which,papers[16,17]present the theory for their combination and the method for load factor calculation. The purpose of this paper is checking the load factor calculated by the new method using a typical bridge case study. The reinforcement of the bridge pier is redesign using the new load factors through element software. The pushover analysis of the redesign pier is carried on and the results are compared with those of LRFD. The results show that the new factor can ensure the safety of the bridge and can be employed in seismic bridge design.
The current Guide Specification for LRFD Seismic Bridge Design uses 1. 25 for dead load and 1. 75 for truck load,but 1. 0 for earthquake alone or 1. 0 earthquake and 0. 5 times truck load for special conditions when considering earthquake effects,which indicates that the probabilistic theory for earthquake and heavy truck load combination is not complete. Based on which,papers[16,17]present the theory for their combination and the method for load factor calculation. The purpose of this paper is checking the load factor calculated by the new method using a typical bridge case study. The reinforcement of the bridge pier is redesign using the new load factors through element software. The pushover analysis of the redesign pier is carried on and the results are compared with those of LRFD. The results show that the new factor can ensure the safety of the bridge and can be employed in seismic bridge design.
引文
[1]AASHTO Guide Specification for LRFD Seismic Bridge Design[S],1st Ed.,Washington,DC.,2009.
[2]AASHTO LRFD Bridge Design Specifications[S],4th Ed.,Washington,D.C.,2007.
[3]Nowak A.S.,Chan-Hee Park,J.R.Casas.Reliability Analysis of Prestressed Concrete Bridge Girders:Comparison of Eurocode,Spanish NORMA IAP and AASHTO LRFD[C].8th ASCE Specialty Conference on Probabilistic Mechanics and Structural Reliability.2000.
[4]Nowak A.S.,Hong Y.K..Bridge Live Load Models[J].ASCE Journal of Structural Engineering.1991,117(9).
[5]R.M.Barker,J.M.Duncan,K.B.Pojiani et al..Manuals for the Design of Bridge Foundations[R].NCHRP Rep.343,Transportation Research Board,National Research Council,Washington,D.C.,1991.
[6]Fred Moses.Calibration of Load Factors for LRFR Bridge Evaluation[R].NCHRP 454[R].Transportation Research Board,National Research Council,Washington,D.C.,2001.
[7]Gongkang Fu,Ji You.Extrapolation for Future Maximum Load Statistics[J].Journal of Bridge Engineering.2011,7/8:527~535.
[8]Laramie WY,Newark DE.Simplified Live Load Distribution Factor Equations[R].NCHRP 592.Transportation Research Board,National Research Council,Washington,D.C.,2007.
[9]NCHRP.NCHRP Report 575[R].Legal Truck Loads and AASHTO Legal Loads for Posting.2007.
[10]Lee,Liang,Shen,Shiuojuka.A Framework for Development of Multi-hazard Load and Resistance Factor Design[R].MCEER Technical Report,2011.
[11]Joseph M.Bracci,Andrei M.Reeinhorn,John B.Mander.Seismic Retrofit of Reinforced Concrete Buildings Designed for Gravity Loads:Performance of Structural Model[J].ACI Structural Journal.1995,92(5):597~609.
[12]Michel Ghosn,Fred Moses,Jian Wang.Design of Highway Bridges for Extreme Events[R].NCHRP 489.Transportation Research Board,National Research Council,Washington,D.C.,2003.
[13]Miranda,E..Strength Reduction Factors in Performance-Based Design[M].EERC-CUREe Symposium in Honor of Vitelmo V.Bertero,Berkeley,CA.1997.
[14]NCHRP.NCHRP Report 575.Legal Truck Loads and AASHTO Legal Loads for Posting.2007.
[15]Wen Y.K..Development of Reliability-Based Design Criteria for Buildings Under Seismic Load[R].1994,8.Buffalo.
[16]孙得璋,孙柏涛,George C.Lee.基于Ferry Borges理论的地震与重卡车作用下桥梁内力的组合问题[J].地震工程与工程振动.2011,31(6):8-13.Sun Dezhang,Sun Baitao,George C.Lee.Study on combination of internal forces on bridges subjected to earthquake and heavy trucks based on Ferry Borges theory[J].Journal of Earthquake Engineering and Engineering Dynamics.2011,31(6):8-13.(in Chinese)
[17]孙得璋,孙柏涛,George C.Lee.桥梁多灾害设计荷载系数确定方法探讨[J].土木工程学报.2012,45(2):76-79.Sun Dezhang,Sun Baitao,George C.Lee.Method of load factor determination for multi-hazards bridge design[J].China Civil Engineering Journal..2012,45(2):76-79.(in Chinese)
[18]陈惠发,段炼.桥梁工程抗震设计[M].机械工业出版社,2008,北京.Chen Huifa,Duan Lian.Bridge Engineering Seismic Design[M].Mechanical industry press,2008,Beijing.(in Chinese)
[19]工程结构可靠度设计统一标准(GB50153-92)[S].北京:中国计划出版社,1992.Unified standard for reliability design of engineering structure(GB50153-92)[S].Beijing:China Planning Press.(in Chinese)
[20]Michel Ghosn,Fred Moses,Jian Wang.Design of Highway Bridges for Extreme Events[R].NCHRP 489.Transportation Research Board,National Research Council,Washington,D.C.,2003.
[2]AASHTO LRFD Bridge Design Specifications[S],4th Ed.,Washington,D.C.,2007.
[3]Nowak A.S.,Chan-Hee Park,J.R.Casas.Reliability Analysis of Prestressed Concrete Bridge Girders:Comparison of Eurocode,Spanish NORMA IAP and AASHTO LRFD[C].8th ASCE Specialty Conference on Probabilistic Mechanics and Structural Reliability.2000.
[4]Nowak A.S.,Hong Y.K..Bridge Live Load Models[J].ASCE Journal of Structural Engineering.1991,117(9).
[5]R.M.Barker,J.M.Duncan,K.B.Pojiani et al..Manuals for the Design of Bridge Foundations[R].NCHRP Rep.343,Transportation Research Board,National Research Council,Washington,D.C.,1991.
[6]Fred Moses.Calibration of Load Factors for LRFR Bridge Evaluation[R].NCHRP 454[R].Transportation Research Board,National Research Council,Washington,D.C.,2001.
[7]Gongkang Fu,Ji You.Extrapolation for Future Maximum Load Statistics[J].Journal of Bridge Engineering.2011,7/8:527~535.
[8]Laramie WY,Newark DE.Simplified Live Load Distribution Factor Equations[R].NCHRP 592.Transportation Research Board,National Research Council,Washington,D.C.,2007.
[9]NCHRP.NCHRP Report 575[R].Legal Truck Loads and AASHTO Legal Loads for Posting.2007.
[10]Lee,Liang,Shen,Shiuojuka.A Framework for Development of Multi-hazard Load and Resistance Factor Design[R].MCEER Technical Report,2011.
[11]Joseph M.Bracci,Andrei M.Reeinhorn,John B.Mander.Seismic Retrofit of Reinforced Concrete Buildings Designed for Gravity Loads:Performance of Structural Model[J].ACI Structural Journal.1995,92(5):597~609.
[12]Michel Ghosn,Fred Moses,Jian Wang.Design of Highway Bridges for Extreme Events[R].NCHRP 489.Transportation Research Board,National Research Council,Washington,D.C.,2003.
[13]Miranda,E..Strength Reduction Factors in Performance-Based Design[M].EERC-CUREe Symposium in Honor of Vitelmo V.Bertero,Berkeley,CA.1997.
[14]NCHRP.NCHRP Report 575.Legal Truck Loads and AASHTO Legal Loads for Posting.2007.
[15]Wen Y.K..Development of Reliability-Based Design Criteria for Buildings Under Seismic Load[R].1994,8.Buffalo.
[16]孙得璋,孙柏涛,George C.Lee.基于Ferry Borges理论的地震与重卡车作用下桥梁内力的组合问题[J].地震工程与工程振动.2011,31(6):8-13.Sun Dezhang,Sun Baitao,George C.Lee.Study on combination of internal forces on bridges subjected to earthquake and heavy trucks based on Ferry Borges theory[J].Journal of Earthquake Engineering and Engineering Dynamics.2011,31(6):8-13.(in Chinese)
[17]孙得璋,孙柏涛,George C.Lee.桥梁多灾害设计荷载系数确定方法探讨[J].土木工程学报.2012,45(2):76-79.Sun Dezhang,Sun Baitao,George C.Lee.Method of load factor determination for multi-hazards bridge design[J].China Civil Engineering Journal..2012,45(2):76-79.(in Chinese)
[18]陈惠发,段炼.桥梁工程抗震设计[M].机械工业出版社,2008,北京.Chen Huifa,Duan Lian.Bridge Engineering Seismic Design[M].Mechanical industry press,2008,Beijing.(in Chinese)
[19]工程结构可靠度设计统一标准(GB50153-92)[S].北京:中国计划出版社,1992.Unified standard for reliability design of engineering structure(GB50153-92)[S].Beijing:China Planning Press.(in Chinese)
[20]Michel Ghosn,Fred Moses,Jian Wang.Design of Highway Bridges for Extreme Events[R].NCHRP 489.Transportation Research Board,National Research Council,Washington,D.C.,2003.
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