ConBeamU Update

Recently a comment pointed out that if the ConBeam, or ConBeamU, user defined functions were used with a single span then the “Out” argument was ignored, so it was not possible to return support reactions.  This has now been fixed and the new version can be downloaded from: ConBeamU

Conbeamu-SS1

For more details of ConBeamU and the related functions see:
Continuous Beam Spreadsheet – with Units

This entry was posted in Beam Bending, Excel, Frame Analysis, Newton, UDFs, VBA and tagged , , , . Bookmark the permalink.

18 Responses to ConBeamU Update

  1. Steve says:

    Hi,

    Can you please explain how I can import these functions into an existing spreadsheet? With an older version of conbeam it was as simple as importing the module that defines the custom function. It does not appear to be quite so simple with this one. My apologies if this is a silly question; I am not very experienced with VBA.

    Thanks,

    Steve

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    • dougaj4 says:

      Steve – a couple of things to check:
      – You will need all the code modules from the original spreadsheet copied across.
      – Look under Tools-References in the VB Editor in the original spreadsheet and check that all the selected ones are selected in your new spreadsheet. The Scripting Runtime module needs to be checked, so that might well be the problem.

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      • Steve says:

        Thanks for your reply. I followed your instruction but it still wasn’t working. Turns out I also needed to copy across the ‘Ext Unit List’ and ‘SIDims’ sheets. Working perfectly now. Thanks for your help.

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  2. dougaj4 says:

    Ah yes, I should have thought of that. Thanks for the feedback; I’ll add a note to the post.

    Also I think I’ll do an add-in version of the units spreadsheet so it can be used with other spreadsheets without copying all the code and data.

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  3. Alberto says:

    Hi, great great great work.
    I have tried conbeam and conbeamu. I set elastic module (E) very high and shear module (G) as normal value. In this way I can see only shear deflection. Well, i have tried beam with left cantilever and one span and try other beam with one span and right cantilever.
    In correspondence with the support of the cantilever, the deformed shear has an angular discontinuity, and in the cantilever the value is incorrect. If I reduce the computation step (X) does not improve the result.
    If i set to 0 the G module and E as normal value, the deflection is correct. I have tested this with FEM software and with file Excel (2003) created by me. I do something wrong? Thanks, Alberto

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  4. Steve says:

    Doug,

    Would it be possible for you to implement a function to determine the translational stiffness of the beam at a specified point? This would be very useful for checking beams supported on another beam.

    Thanks,

    Steve

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    • dougaj4 says:

      Steve, can’t you just apply a unit load, then the stiffness is 1/deflection?

      Like

      • Steve says:

        Doug,

        I did consider this approach. However, I am looking to use this in a spreadsheet where I am analysing multiple beams in the one workbook and I was hoping to be able to calculate the translational stiffness in a single cell to avoid have to set up a dummy load case for it.

        Is it possible to do this in a single cell with the current functions? Would I be able to pull out just the deflection value using INDEX?

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  5. dougaj4 says:

    If you enter the x value of the point of interest as the first of the output x values (the “outpoints” range), the results for that location will be in the top row. You could then use the Index function to just return the deflection, and take the inverse of that to give the stiffness value. Note that the list of output points must be at least 2 rows, but the second point could be a space, or even the x value for a different beam.

    Will that do what you want?

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  6. Seth says:

    Hi there,

    I’m having issue with the ConbeamU function for the support moment reactions. For validation sake, I’m just looking at a fixed-fixed beam (translation and rotation stiffness high) at the start and end points with an evenly distributed load. The out=1 output correctly shows a moment sustained at either end of the beam, however the out=2 output gives moment reactions of ~0.

    As a side note, the FEA and REA functions return the correct values for the analyzed scenario.

    Like

    • dougaj4 says:

      It seems to be a problem with 1 span beams only. 2 or more spans give a moment reaction at each end with out = 2.

      I will have a look and fix it, but in the meantime the out = 1 results for either end should be ok.

      Like

  7. Tim says:

    Doug,
    Am I right in suggesting that the sign convention use for the “moving load” tab is opposite to the sign convention use for the “conbeam” tab?

    Like

    • dougaj4 says:

      A downward load applied to the beam is always negative, but the vehicle definition table is specifying the axle weights of the vehicle, not the load. These are factored by the factors in F22:F24, and by -1, because it is a downward load.

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  8. Lifu Liu says:

    Hi there

    Probably a silly question. Seems like the spreadsheet (ConbeamU)can only show 4 reaction results? I defined 7 supports, but only can see the results of reactions for 4 of them. Looking forward to hearing from anyone.

    Like

    • dougaj4 says:

      Not a silly question.
      The easiest way is to revise the values in the column headed “X” (spreadsheet column J) so that they cover the full length of your beam.

      If you want to increase the length of the output table:
      – Enter the X values you want.
      – Edit the output function so that it reads the full range of X values. If your values go from row 22 to 82 the formula would be:
      =Conbeam($B$6:$C$16,J22:J82,$E$6:$E$16,$B$21:$E$53,$F$21:$H$53)
      to enter the revised formula you need to press Ctrl-shift-enter
      – Select the entire output range (K22:N82 in the example), press F2 to enter Edit mode, then press Ctrl-Shift-Enter.

      Like

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