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tension loads in RISA Connection

tension loads in RISA Connection

tension loads in RISA Connection

This probably a question for Andrew and/or Josh.

In RISA Connection, I am trying to design baseplates for uplift. With WF Columns, RISA Connection won't solve flexural yielding of plate if the anchor bolts are located inside the flanges. The error says "This configuration of bolts is not allowed for strong axis moment." However, I actually don't have strong axis moments on the connection. It is a pinned connection.

Is this an error in the program?

Thanks, Cody

RE: tension loads in RISA Connection

I just figured it out. RISA was apparently bringing in a strong axis moment that was negligible, but not allowing the calculation to run. The moment showed as 0.0000 in the loading input data, but when I overrode the automatic loading input to custom and changed the number to 0, it ran just fine and passed. That is weird... I went back to my RISA model and sure enough, my connections are pinned and no moment shows up in the joint reactions. Must be an error in RISA Connection.

RE: tension loads in RISA Connection

There is probably something in RISA-3D that is causing a slight moment. I remember seeing this once before. But, I don't remember the exact circumstances.

I obviously don't have access to my RISA support archives anymore. But, I'll guess it was a fixed boundary condition with a BenPin column coming into it that wasn't perfectly vertical. So, you might get a teeny, tiny bit or torsion in the column. Then that torsion(because the column isn't perfectly vertical) has a very minor reaction in the strong axis. It shows up as zero in RISA-3D display because the program displays zero for any number below a certain amount. But, when it exports the forces over to RISAConnection, it exports the non-zero force.

It's sounding more and more familiar to me as as write it up. Ultimately, this is what we users call a bug, but which the developers insist is NOT an actual bug. I'm pretty sure I wrote it up as a bug that could be fixed either on the RISA-3D side or the RISAConnection side. Just by being consistent with the RISA-3D program display about what constitutes a zero reaction. However, this is the type of "minor bug" that sometimes gets kicked down the road a bit. Minor issue, hard to trigger, and there's a way to work around it when you realize what's happening. It should still get fixed eventually (unless Nemetschek / Amber de-priortize bug fixing), it just has to wait a while.

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