Wall Panel Boundary Conditions

[Stazz]

When these wall panels are created in Risa Floor and then transfered to Risa 3d, how do the bases of these walls act? It shows a pin on the bottom corners of the wall but the node at these pins is translating down.

What I'm actually trying to do is support the bottom of the walls on rigid beams. I have 4 walls of a stair shaft, and I want the entire shaft to bare on beams so that I can support those beams with a single fixed node boundary condition at the middle of the shaft hoping that this will capture the entire load, shear load and most importantly the overturning moment of the stair core so that I can design the mat for it (and transfering that point to Risa Foundation so that it can optimize a footing for me.

So far I've been striking out and I just need to now how these wall boundary conditions are behaving.

 

[JoshPlumSE]

Stazz -

The first question should really be if you are using the 8.0 version or the 8.0.2 (or higher) version of RISA-3D. The initial release of wall panels experienced a number of odd little issues like this.

Assuming that you are running 8.0.2, then the wall panel editor will allow you to define specific boundary conditions for each "edge" of your wall. This is what the program should be using.

The question then becomes "what happens at the corner joint if you specify a "pinned" boundary condition at the base, but a free or released boundary condition at the side?"

We are supposed to take the more restrictive of the two. If not, then please send the e-mail into the tech support group (support@risatech.com) and they should answer it pretty darned quickly.

Josh

 

[Stazz]

I'm actually running 8.0.1. Is this ok?

Will it be possible to support these walls with beams and continue the load path to where I wish, or do the walls have to be fixed with reactions?

 

[JoshPlumSE]

I'd strongly recommend installing the 8.0.2 update. I'd have to review the release notes and such to be 100% sure, but I believe there was an issue in 8.0.1 where the program did not like unsupported walls.

That doesn't actually sound bad, but think of the situation where you have a wall that was supported by a transfer girder or a slab rather than a boundary condition. This may actually be your exact issue.

In those cases, the program was automatically adding in a boundary condition at the base of the wall.

 

[Stazz]

Ok, I finally got the 8.0.2 update and I was able to get the fixity of the walls to be free at their bases (and stay free). I guess this was a glitch in the previous version where the walls always provided pinned boundary conditions at its base after you ran it.

The method I described above works perfectly now, I was able to get the entire reaction from the wall core into a single point at its center using rigid links. This is AWESOME!. Now I can get a quick Mat design (based on stability) for the CMU core. I love computers.