Getting weird (BIG) strip foundation width beneath walls

[egil.arne]

Hi everyone.

I’m new to this forum, but I’ve used RSA for a few years now. I have a “problem” that I hope some of you on this forum can help me with.

I’m currently designing a building in RSA, and I’m trying to design foundations for this structure.

But I get unreasonable results.

I’ve checked the reactions forces in the nodes in the model, but when I transfer the “nodes” to foundation design, it seems to get a lot of uplift, so the check “fails” due to lack of contact surface.

Maybe I’m modelling this the wrong way, but I seem to struggle with this foundation module in RSA.

Picture of the model, with the higligted wall that I'm trying to design a footing for.

Below a section cut of the wall.

  

I have checked the resultant reactions from the results, from the varius loads.

I have only made one loadcombination for now, (will make the required combinations when i understand this problem) due to RSA gets slow and laggy when I add combinations.

In the model i have Dead loads ( selfweight, soilpressure), liveloads, snow- and wind loads.

Foundation design:

 

Foundation results

What am I doing wrong here?

Regards 

Egil

 

[egil.arne]

Following up on this.

I changed the supports from pinned linear support to an elastic linear support. This changed the results in foundation design to be more realistic.

Foundation result:

Is this a right way to do this? Any suggestions on how I can verify these results in RSA?

And a question about applying soil pressure to the walls.

I have currently added soil pressure to the walls like this

What is right to do? Transfer the nodes from wall without backfill (soil load), and model the backfill again in soil definition for the foundation module? Or do I need to transfer the soil loads from the wall and not add backfill in foundation design module?

Regards 

Egil