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    Impact Load Calculation

    Uploaded by

    Akshay Agatkar
    This document discusses methods for calculating impact loads from passing trains according to various standards: 1. Per IRS Bridge Rule, the Coefficient of Dynamic Augmentation (CDA, or impact factor) depends on span length and ranges from 15-23%. This is only valid up to 160 kmph. 2. Spanish IAPF 2006 Code and SNCF Document give equations relating impact factor to characteristic length and train speed up to 220 kmph. Above 220 kmph, full dynamic analysis is required. 3. UIC method relates impact factor to equivalent span, train speed, and structure's natural frequency. 4. Japanese Code gives two impact factors - one for speed effect and one for vehicle

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    Impact Load Calculation

    Uploaded by

    Akshay Agatkar
    118 views2 pages
    This document discusses methods for calculating impact loads from passing trains according to various standards: 1. Per IRS Bridge Rule, the Coefficient of Dynamic Augmentation (CDA, or impact factor) depends on span length and ranges from 15-23%. This is only valid up to 160 kmph. 2. Spanish IAPF 2006 Code and SNCF Document give equations relating impact factor to characteristic length and train speed up to 220 kmph. Above 220 kmph, full dynamic analysis is required. 3. UIC method relates impact factor to equivalent span, train speed, and structure's natural frequency. 4. Japanese Code gives two impact factors - one for speed effect and one for vehicle

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    Impact Load.docx

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    This document discusses methods for calculating impact loads from passing trains according to various standards: 1. Per IRS Bridge Rule, the Coefficient of Dynamic Augmentation (CDA, or impact factor) depends on span length and ranges from 15-23%. This is only valid up to 160 kmph. 2. Spanish IAPF 2006 Code and SNCF Document give equations relating impact factor to characteristic length and train speed up to 220 kmph. Above 220 kmph, full dynamic analysis is required. 3. UIC method relates impact factor to equivalent span, train speed, and structure's natural frequency. 4. Japanese Code gives two impact factors - one for speed effect and one for vehicle

    Copyright:

    © All Rights Reserved
    Download as DOCX, PDF, TXT or read online from Scribd
    Download as docx, pdf, or txt
    118 views2 pages

    Impact Load Calculation

    Uploaded by

    Akshay Agatkar
    This document discusses methods for calculating impact loads from passing trains according to various standards: 1. Per IRS Bridge Rule, the Coefficient of Dynamic Augmentation (CDA, or impact factor) depends on span length and ranges from 15-23%. This is only valid up to 160 kmph. 2. Spanish IAPF 2006 Code and SNCF Document give equations relating impact factor to characteristic length and train speed up to 220 kmph. Above 220 kmph, full dynamic analysis is required. 3. UIC method relates impact factor to equivalent span, train speed, and structure's natural frequency. 4. Japanese Code gives two impact factors - one for speed effect and one for vehicle

    Copyright:

    © All Rights Reserved
    Download as DOCX, PDF, TXT or read online from Scribd
    Download as docx, pdf, or txt
    of 2

    Impact Load Calculation

    A. As per IRS: Bridge Rule

    Coefficient of Dynamic Augmentation (Same as Impact factor) depends on the span length and is
    given by

    CDA=0.15+ ( 6+8 L )
    But, the validation of this relation is valid only with the trains moving with speeds up to 160
    Kmph.

    B. As per Spanish IAPF 2006 Code


    Impact factor is given by the expression,
    1.44
    ɸ 2= +0.82
    √ Lɸ −0.2
    Where Lɸ =Characterstic length of Viaduct .
    The validation of this expression depends on following conditions,
    a) Upper speed limit should not be greater than 220 Kmph.
    b) The frequency of viaduct should be in between the upper and lower bound.
    f min =2.73 Hz and f max =6.23 Hz
    For the trains moving with speed greater than 220 Kmph, a complete and specific dynamic
    analysis of structure in high seed lines is required. From the results of analysis, the impact
    coefficient ɸ is obtained and compared with ɸ2. Maximum of two is considered for design.
    δ idin, rel
    ''
    ɸ=(1+0.5 ɸ )
    δ est ,tipo
    where,
    δ idin, rel =Max . movement obtained for thei ' thtrain .
    δ est , tipo=Movement obtained statically using the train defined∈IAPF 200 6
    ɸ' ' =Cefficient related with tracking irregularitis

    C. As per SNCF Document (French National Railway Company)


    For the trains running below 220 Kmph,
    1.44
    ɸ 2= +0.82
    √ Lɸ −0.2
    1.0< ɸ2 <1.67
    L} rsub {ɸ} ¿ is the characteristic length depending on the span length and distribution, the
    deck structural element.
    For trains running with speed > 220 Kmph,
    δ dyn
    ɸr =max ( )
    δ sta
    D. As per UIC (The International Union of Railways)

    K
    ɸ' =
    1−K + K 4

    λ
    K=
    2 Lɸ

    v
    λ=
    f0

    L} rsub {ɸ} ¿ is the equivalent span of the element under study, v is the train speed and
    f} rsub {0} ¿ is the first natural frequency of deck vibration.

    δ sta,real
    ɸ ≥ max ⁡(1+ ɸ' +ɸ' ' )
    δ sta ,UIC 71

    E. As per Japanese Code,


    ɸ=( 1+i α ) ( 1+i c )

    V Lb
    i α =Impact factor for speed effect where iα =f ( ,
    n Lb L v )
    10
    i c =Impact fac t∨for vehicle motion where i c =
    65+ Lb

    V =Maximum velocity of Train( Kmph)

    n = Fundamental frequency of viaduct

    Lb=Span of viaduct

    Lv =Length of Vehicle

    As per IRS: Bridge Rule, the value of Impact factor is found to be 40.8%. The NHSRL report does not
    provide the direct value of i α therefore, the impact percentage considered to be 40% in the present
    study.

    Therefore, Live Load intensity with CDA = 153.8 KN/m.

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