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Thread: Verification of modal analysis Results

  1. #11
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    Default Re: Verification of modal analysis Results

    Quote Originally Posted by length zero View Post
    Mech
    Maybe it can help you
    When u use directional X=2 it means that you have doubled seismic force in that direction
    Hi Z.G
    X ,y and Z are only vectors not values
    it is like i, j, K in vectors
    X means the program will put the mass in X- direction
    and Y and Z same Things

  2. #12
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    Default Re: Verification of modal analysis Results

    Edward and Length zero
    Which you are right?
    where is the scale factor of seismic loads. Please can you show in jpg. screenshot? I'm so confused. thanks

  3. #13
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    Default Re: Verification of modal analysis Results

    If u need to define seismic regarding to EC - i can helep, and you dont need scale factor
    If u need to perform via UBC - mecheil can help you
    Regards
    Z.G. ( Lengh Zero)

  4. #14
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    Default Re: Verification of modal analysis Results

    Mechil
    In EC i use this values to determine direction of seismic excitation,
    And if i want to use 120% of seismicX loads and 35% of seismic Y loads, you must put X=1.2 and Y=0.35, ( this mean in this case you have apply 1.2SX+0.35SY - in one case)
    i MEAN SO : Put 1 on X and read Base shear And for example 100kN, Go again and put in x=2 and you will get base shear 200nK, and i mean this you can use to scaling forces by seismic excitation, And maybe this is an SCALE FACTOR to EC, ahhah
    Regards
    Z.G.

  5. #15
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    Default Re: Verification of modal analysis Results

    Quote Originally Posted by troy_the.best View Post
    Edward and Length zero
    Which you are right?
    where is the scale factor of seismic loads. Please can you show in jpg. screenshot? I'm so confused. thanks
    Hi troy,
    see follow this steps to show meaning of x,y,z directions byspectrum analysis by ubc code
    1-go to menu analysis
    2-select : analysis type
    3-one form will open and you will see seismic ubc x .....
    (these cases you defined before)
    4-select seismic ubc _x and under the window click on parameters
    5-you will get new window click on direction
    6-u will get new window contains X Y and Z
    when you type 1 in X this means the program will generate seismic forces in x direction
    when you type 0 in x and 1=y and 1=z this means the program will generatw forces in y directiona+z direction and so on

    usually we will put for seismic_x we put x=1 y=0 z=0
    for seismic_y we put x=0 ;y=1; z=0
    and if you would like to generate one seismic load to consider x+y we put in this case
    x=1 ;y=1
    hoping this clear

  6. #16
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    Default Re: Verification of modal analysis Results

    Edward,

    yes you are righ but It means when we say the same things.

    direction in robot=scale factor in etabs

    isnt it?

    best regards
    falconado_turkey

  7. #17
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    Default Re: Verification of modal analysis Results

    Quote Originally Posted by troy_the.best View Post
    Edward,

    yes you are righ but It means when we say the same things.

    direction in robot=scale factor in etabs

    isnt it?

    best regards
    falconado_turkey
    See falconado, Now I try one other thing
    Forget now scale factor ok
    run the seismic analysis ok.
    get the base shear from dynamic analysis say 1000 KN ok and say the name of case is Seismic_x
    calcultae the static base shear say 500 KN.
    now go to combinations and make a new case say Comb1 and use the case: seismic_x multiply into combination scale = 500/1000 = 0.5
    Now you get the same idea of scale factor
    but when you start design do not use Seismic_x but use Comb1
    Hoping this is good

  8. #18
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    Default Re: Verification of modal analysis Results

    Quote Originally Posted by length zero View Post
    Mechil
    In EC i use this values to determine direction of seismic excitation,
    And if i want to use 120% of seismicX loads and 35% of seismic Y loads, you must put X=1.2 and Y=0.35, ( this mean in this case you have apply 1.2SX+0.35SY - in one case)
    i MEAN SO : Put 1 on X and read Base shear And for example 100kN, Go again and put in x=2 and you will get base shear 200nK, and i mean this you can use to scaling forces by seismic excitation, And maybe this is an SCALE FACTOR to EC, ahhah
    Regards
    Z.G.
    Z.G thanks for your post
    But believe me x,y,z is a only a direction vector in masses by using ubc
    x=1 means but forces of masses from newton equations in x-direction
    x=2 same thing
    but yuor concept is valid only when you apply x=1 and y=2
    this means you have a vector force F=1i +2j
    then the program will prepare a new unit vector
    hoping you get my point

  9. #19
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    Default Re: Verification of modal analysis Results

    Quote Originally Posted by mecheil.edward.hanna View Post
    Z.G thanks for your post
    But believe me x,y,z is a only a direction vector in masses by using ubc
    x=1 means but forces of masses from newton equations in x-direction
    x=2 same thing
    but yuor concept is valid only when you apply x=1 and y=2
    this means you have a vector force F=1i +2j
    then the program will prepare a new unit vector
    hoping you get my point
    edward,

    I understood what he meant. Please do not be attached to the term. x = i, y = j say. all misunderstood anything. sonuçte F = 1 i + 2 j is the mean resultant force vector. that can not scale well. How well do you scale factor logging. (If you're changing coefficients in the combination?) jpeg screenshot please attaching menu.

    Thank you again for interest on.

    falconado_turkey

  10. #20
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    Default Re: Verification of modal analysis Results

    Hi Troy
    Hi Z.G
    Please get the link for this pdf file
    this file show u step by step seismic load by ubc
    But still scale factor without solution by robot
    as I told before we can generate a new combination and multiply the seismic load by the required scale factor
    Hoping it will be useful
    http://www.4shared.com/file/QoEHcxiR/ToTroyAndZG.html

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