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Bug in member strains with trapezoidal temperature load

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  • Bug in member strains with trapezoidal temperature load

    I have a strange bug in RFEM 5.23.01.
    For beams that only have temperature loads, and of wich at least one loadcase includes a trapezoidal temperature load, the strains of the first node are shown incorrect (usually as 0)

    Steps to reproduce:
    Create a new model in 3D.
    Draw a new single member. make it a EN - IPE80 steel beam, make 1 node a rigid support.
    Add one loadcase, disable selfweight. Give it a member load: Temperature, uniform Tc = +10 degC
    Calculate.
    Now look at table 4.8: Member strains.
    For member 1, Both node 1 and node2 show a strain (ex,max and ex,min) of approx 0.12 mm/m. This is correct. See picture 1.


    Now add a second loadcase. (don't touch the first one!)
    In the second loadcase, assign a member load: Temperature, trapezoidal Tc1=+10, Tc2=+9
    Calculate.
    Now look at table 4.8: Member strains for the first loadcase
    For member 1, node1 now has a strain (ex,max and ex,min)of 0. This is obviously incorrect. See picture 2.

    In the result diagram it is clear that node 1 has 2 strains at the same point. 0 and 0.12mm/m. See picture 3


    While this may not hurt the global results, if you export table 4.8 to excel and use those values, it results in big errors.





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  • #2
    And to continue on this:
    Delete the uniform load from loadcase1.
    Add a new trapezoidal temperature load in loadcase1: Tc1=Tc2=+10.
    The result now looks like this: (see picture)
    Klicke auf die Grafik für eine vergrößerte Ansicht

Name: ex1.png
Ansichten: 49
Größe: 61,0 KB
ID: 3193
    Node 1 now has 2 lines, that show different stresses at the same position.....

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    • #3
      Hello cohen, thank you very much for the hint and the good documentation. We will correct the problem in the next RFEM version.

      Frank Faulstich
      Support Team der
      Dlubal Software GmbH
      info@dlubal.com
      https://www.dlubal.com

      Kommentar


      • #4
        Zitat von Frank Faulstich Beitrag anzeigen
        Hello cohen, thank you very much for the hint and the good documentation. We will correct the problem in the next RFEM version.

        Frank Faulstich
        Thank you for the swift response.

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