Convert vertical load to horizontal load

Hi All

Here in Denmark Seismic loading is merely defined as a percentage of the applied vertical load. In the past i've used NOTIONAL LOADS to create this and it worked fine. But only for Y axis as global vertical axis. I now use SET Z UP since it corresponds to the axis definitions all our clients use.

However, notional loads doesn't seem to Work properly when the command SET Z UP command is used. Can anyone explain this?

The alternative is to manually copy all vertical loads and change direction in the STAAD.Editor. But this is a very time consuming task and it also rather frustrating since loads tend to change a lot during the design phase.

Can anyone help me to explain this or alternatively give me a tip to avoid the manual re-entry of loads? Perhaps someone has created a macro for a similar task?

Thank You.

Kind regards

Morten

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  • The SELFWEIGHT load command can be used to apply any fraction of gravity in any of the global axis directions, perhaps that would work well for you. I've done that in STAAD.pro and Ram Elements personally. If you have an example of how notional loads were malfunctioning with Z up, please send it along for review.



  • Hi Seth

    Thank you for your reply. Unfortunaly most of the vertical load the needs to be applied isn't selfweight from the structure but DL from equipment and so forth. I've made a small example in STAAD for a simple structure, but i'm not sure how to upload it? For the time being i will paste the command lines from STAAD.Editor:

    I've set the notional load to 0.015 times the vertical load. In the example STAAD should convert the 400 kN to 6 kN horizontally in case 2. It works fine in the Y-case, but in the Z-case no horizontal load is applied in case 2.

    Y UP

    STAAD SPACE
    START JOB INFORMATION
    ENGINEER DATE 16-Oct-14
    END JOB INFORMATION
    INPUT WIDTH 79
    UNIT METER KN
    JOINT COORDINATES
    1 0 0 0; 2 5 0 0; 3 0 5 0; 4 5 5 0; 5 0 0 5; 6 5 0 5; 7 0 5 5; 8 5 5 5;
    MEMBER INCIDENCES
    1 3 4; 2 1 3; 3 2 4; 4 7 8; 5 5 7; 6 6 8; 7 3 7; 8 4 8;
    DEFINE MATERIAL START
    ISOTROPIC STEEL
    E 2.05e+008
    POISSON 0.3
    DENSITY 76.8195
    ALPHA 1.2e-005
    DAMP 0.03
    TYPE STEEL
    STRENGTH FY 253200 FU 407800 RY 1.5 RT 1.2
    END DEFINE MATERIAL
    MEMBER PROPERTY EUROPEAN
    1 TO 8 TABLE ST 140x8SHS
    CONSTANTS
    MATERIAL STEEL ALL
    SUPPORTS
    1 2 5 6 FIXED
    LOAD 1 LOADTYPE Dead  TITLE DL
    JOINT LOAD
    3 4 7 8 FY -100
    LOAD 2 LOADTYPE Seismic  TITLE NOTIONAL
    NOTIONAL LOAD
    1 X 0.015
    PERFORM ANALYSIS
    FINISH

     

    Z UP

    STAAD SPACE
    SET Z UP
    START JOB INFORMATION
    ENGINEER DATE 16-Oct-14
    END JOB INFORMATION
    INPUT WIDTH 79
    UNIT METER KN
    JOINT COORDINATES
    1 0 0 0; 2 5 0 0; 3 0 0 5; 4 5 0 5; 5 0 -5 0;
    6 5 -5 0; 7 0 -5 5; 8 5 -5 5;
    MEMBER INCIDENCES
    1 3 4; 2 1 3; 3 2 4; 4 7 8; 5 5 7; 6 6 8; 7 3 7; 8 4 8;
    DEFINE MATERIAL START
    ISOTROPIC STEEL
    E 2.05e+008
    POISSON 0.3
    DENSITY 76.8195
    ALPHA 1.2e-005
    DAMP 0.03
    TYPE STEEL
    STRENGTH FY 253200 FU 407800 RY 1.5 RT 1.2
    END DEFINE MATERIAL
    MEMBER PROPERTY EUROPEAN
    1 TO 8 TABLE ST 140X8SHS
    CONSTANTS
    MATERIAL STEEL ALL
    SUPPORTS
    1 2 5 6 FIXED
    LOAD 1 LOADTYPE Dead  TITLE DL
    JOINT LOAD
    3 4 7 8 FZ -100
    LOAD 2 LOADTYPE Seismic  TITLE NOTIONAL
    NOTIONAL LOAD
    1 X 0.015
    PERFORM ANALYSIS
    FINISH

    I hope You can help

    Kind regards

    Morten

     

     

  • You are correct. Seems like there is an issue with notional loads when it comes to the Z - UP system. I am going to log this in our bug tracking system.



    Answer Verified By: MortenHK 

  • Has this been solved? I too have a problem regarding notional loads when set z up is used. Notional loads do not function when set z up is used.
  • Yes this problem has been addressed in the STAAD.Pro version 20.07.10.65.



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