SSPM Wall and Slab Connection and Releases

Is there a way to control releases between the wall and slab in the physical modeler? 

I'm trying to model a wall that is supported by a slab, but I do not want the wall to stiffen the slab. Can I release the connection between the two elements?

I suppose my question also applies to the slab that is supported by a wall. Can I adjust whether those nodes are rigidly connected vs pin connected?


  • You can change these restraints in the Edge restraints spreadsheet:

  • Thanks!

    I have a few additional questions if you don't mind. 

    I'm trying to create a model where the slab does not engage the wall but will still support the wall's gravity load. Essentially, I'm trying to avoid this affect:

    Does this release achieve that? Or does the wall just fall through the slab (Or they are "sliding" off the slab? see more on this below). 

    I tried to pin one "corner restraint" to avoid "sliding"? Does this "pin" the corner to the slab? Or does it pin it to space? It seems if I only pin one corner, the walls "tip over". So I assume that the corner pin means that only this node is "pinned" to the slab and the remainder are "free", but it seems like they fall through the slab. 

    2. Regarding "corner restraints". The definition of "None = determined by the boundary conditions". Does this mean that it matches the "edge restraint condition"?

    3. How do I load the top edge of the wall with a line load?

    4. I've compared two walls:

    The left wall in the image below has the bottom surface edge = free and both bottom corner restraints = pinned. 

    The wall on the right has bottom surface edge = fixed and corner restraints = none. 

    It appears that this eliminates the wall from stiffening the slab, but in my mind, it must be contributing some because the two corner nodes are still pinned. Any thoughts on this? I tried to only pin one corner, but I get strange results (see second image below). 

    Only one corner pinned:

    Lastly - thanks for making it easier to copy/paste images into the forum.

  • 1) If you set wall's edge and its corners as Free, then instability will occur as the wall will not be connected to the slab. If you use Pin for a single corner only (remaining edge and corner is Free), the wall will spin around that corner which will also cause the instability.

    2) Yes

    3) Create a Reference Line at that top edge of the wall and then apply line load to the Reference Line.

    4) If both corners are pinned but the remaining edge is free, then the slab will be much more flexible compared to the model where whole wall's edge is fixed. I believe that there should be some stiffening effect even with only both corner nodes pinned. To see the effect of it, you may model a slab without a wall, just with the same load at the location where wall connects with the slab. I believe that the results will be a bit different (from the model with only corners pinned), though I would not expect anything very significant.

  • Thanks for the replies!

    My ultimate goal is to figure out a way to model a wood or CFS shearwall sitting on a concrete podium slab. I think the pinned corners might be an easy enough tradeoff between modeling effort and accuracy. The slab should be fairly stiff compared to the wall so I'd imagine the effect would be minimal (still need further testing). 

    However, it still might be fun to think of a way to let the slab move freely without the stiffening affect, but also not have any instabilities. The only way I can think of at the moment would be to add some sort of dummy elements on the end of the wall that isn't pinned to the slab.  

  • Why then you want to model that wood wall at all if it does not have any structural impact? For the graphical representation only? For the simplicity, I would simply apply the line load on the slab where it is intersected by a wall.