Risa Foundation for PEMB

[CBSE]

Has anyone used RISA Foundation for Pre Engineered Metal buildings? I'm looking at purchasing the software to compliment other programs.

What are people's thoughts on the program in general?

 

[JoshH726]

CBSE, I am also looking at using RISA Foundation for PEMB foundation design. In general, I like the link between RISA 3d and Foundation. Specific to PEMB foundation design, I'm not exactly sure how the presences of beams linking two foundations is resisting the lateral thrust force usually associated with PEMB design. I would think the beams should function like grade beams. The beam detail report indicates the beams are not designed for axial loads (which I would think then disqualifies this as a grade beam).

JoshPlum may be able to offer guidance in this matter as well.

 

[CBSE]

Thanks. I thought Josh would respond to this but maybe not. I will probably email risa and ask them about the grade beams. That's my biggest question. I like the program so far.

 

[JoshPlumSE]

Whether it's RISA-3D or RISAFoundation, Concrete beams are not designed for axial forces. That doesn't mean they're not analyzed for axial forces. Just that the design code checks don't include them.

To do this correctly for concrete you would have to generate some sort of interaction diagram like you have for columns. If this were RISA-3D, I'd tell you to call the member a "column". But, we don't have that option in RISAFoundation.

Note:
I was out of town when these messages were first posted. So, I didn't notice the thread until JoshH's response.

 

[CBSE]

Thank you for the quick response!!! That certainly clarifies the questions.

 

[JoshH726]

CBSE, have you been using the beam members to resist the thrust? Or some other way? I haven't found a good way to take out the lateral movement in the foundations. JoshPlum, any thoughts?

 

[CBSE]

Up until this point, I have not used any grade beams to resist the lateral movement for the reason Josh explained that the program does not treat the grade beams as columns to resist axial forces. Now I did not know that exactly, but had my suspicions so I didn't rely on it.

For my metal building foundation designs, I have been relying on the soil and hair pins into the slabs. I bought the book "Foundation and Anchor Design Guide for Metal Building Systems" quite a while back. I had built spreadsheets based on that book and have been trialing them along with programs, but I like Risa so far. If you don't have the book, I would suggest getting it.

Looking forward though, I'm wondering now if I could use my turn-down slab edges as grade beams to help resist the lateral loads which I have not done in the past. I suppose I could assume a grade beam, then look at it as a column to verify it would work.

 

[mike20793]

It's pretty standard to resist the thrust by either tie beams (for higher thrusts) or hairpins.