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.

  • 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.

  • Line loads and point loads are definitely an option because there is some cheating involved to get the entire model. I'm imagining you have say 5 stories over 1 or 2 stories of parking with the bottom levels being concrete or steel. I'd like to model all the wood/CFS walls and the floor diaphragm of the tower for a couple reasons. Ideally I'd be able to apply a uniform load to the floor. The floor diaphragm is flexible out of plane so hopefully the loads go to the walls more/less based on tributary width (i.e. one way spanning slab). This eliminates a bunch of hand calcs to get the line loads. I'm finding walls parallel to the "one-way" span are picking up a fair amount of load though. (Need to think if there is a way to get around this). This aspect of modeling is done fairly easily in RAMSS, but I run into issues when walls are offset with the levels below. Next is the lateral aspect. If I model the entire structure, (including effective diaphragm thickness) I can get the loads on the shear walls and the point loads at the ends of the walls are applied to the transfer slab. The problem though is that not all walls are shear walls. So I'd need a way to transfer only gravity loads to certain walls. 

    The above can be done in RAMSS to a certain degree. RAMSS has its own issues with this type of building. I am trying to see if it is viable in Staad as the new Physical Modeler has made things faster to model. I really would need the two following items to make things work:

    One-way spanning slabs similar to RAMSS. If there was a way to have one-way spanning slabs that would be helpful. I know there is some functionality already, but I'm pretty sure I'd have to put in 100's of panels to get the one-way panels to distribute to the walls. I can't just put in one large panel over the entire floor perimeter like I can in RAMSS. Maybe I'm wrong here. I know this functionality would be hard to implement because when you do it in RAMSS you always get about 30 errors the first time you model something and that's constrained to model one floor at a time. Maybe I'm stuck with the panels for now. Or maybe at least let the panels go over multiple walls. 

    Gravity walls. Walls that only transfer loads vertically. Somehow release the in-plane shear of the wall. Maybe I shouldn't call them gravity walls, because I think it's ok if they transfer vertical load due to a lateral load. So maybe I call them "vertical load only walls" or something to this effect. 

  • Sorry, I am not sure if this can be achieved in SPPM.

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