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Truss designer results

Started by lapsmith, January 25, 2024, 08:17:41 AM

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Hi, new user here.  I have a few questions on the results of the truss designer. 

When I use identical loading conditions and identical truss width and spacing, I get different results, depending on the type of truss analyzed (I am referring mostly to the results for the reactions at each end of the truss).

For example, I used a 25 foot span with loading of 10psf live and 5psf dead and 13 foot spacing.  When I run the case with a Howe truss, the results are different than with a Fink truss.  The vertical loads don't match. The heights of the trusses are different by about 3 inches, which is understandable, but the reactions at each end are different.  For the Howe truss, the reactions at each end are 3770 lbs (vertical axis) while for the Fink truss, the reactions are 2643 lbs at each end.  How can there be such a difference?  I can understand a slight difference due to the weight of the truss, but I am obviously doing something wrong. 

Another question is that the sum of the forces in the Y direction don't balance.  If I sum all of the vertical loads shown on the results sheet, they are less than the reactions at the two ends.  Is the difference due to the weight of the truss?

Thanks for any guidance.


Wow, over 1200 views and no replies.  I didn't think it was a tough question:-)


Can you duplicate the results for each truss type and then save the results to a PDF, then email it to me so I can take a look at it.
Nathaniel P. Wilkerson, P.E.