I'm trying to help another engineer in my office determine forces in some footings using Risa 3D. He isn't comfortable with the results and wanted me to do a comparison on a simple dummy model using Ram Elements and spMats to verify that each program has similar outputs.
When comparing the M11 moments in Ram to Mxx in Risa and spMats what I found was Ram had the highest moments while Risa and spMats were a good bit lower but still not agreeing with each other.
The dummy model was a 10x10x1 footing with a 50k load at the center and pinned supports at each corner. The self weight of the concrete was included in the solver with no additional load factors.
Risa's output is Mxx, Myy, and Mxy which I assume is similar to M11, M33, and M13 in Ram.
Risa's help manual states that for footing design you need to add Mxy to Mxx or Myy to get the "true moment".
Does Ram output M11 and M33 with the contribution of M13 by default? If I subtract M13 from M11/M33 the results agree more with the other 2 programs.
If not, what type of plate does Ram use? I haven't been able to find it in the user manual.
Thank you for your time.
