Max Number of Allowed Load Combinations?

Question

Max Number of Allowed Load Combinations?

ben.drane.cobuilt (Civil/Environmental)

(OP)

7 Sep 22 15:36

We're analyzing a structure with robotic loads on it that can occur at different instances in time. We potentially want to evaluate 65,000 LC's in a solve. Does Risa allow this?

I see in the literature that up to 1000 BLC's are allowed but I haven't found anything on LC's.

driftLimiter (Structural) · Answer 1 · 2022-09-07 15:41:16

That sounds interesting. 65k load combos is quite a few. Perhaps some of the cases could be better expressed as dynamic loads?

WinelandV (Structural) · Answer 2 · 2022-09-07 15:56:25

Without knowing the layout of these robotic loads, trying to treat them as a moving load (instead of nodal or member loads) could help with reducing the # of LC's.

Please note that is a "v" (as in Violin) not a "y".

ben.drane.cobuilt (Civil/Environmental) · Answer 3 · 2022-09-07 16:08:37

Thanks for the suggestions. The robots aren't moving along the structure but their base is fixed in place and they apply forces and moments to the structure at a single point.

driftLimiter (Structural) · Answer 4 · 2022-09-07 16:34:33

A few thoughts are to attempt to find the extreme forces in each restrained DOF and then apply them simultaneously as static loads. The other option would be to make some dynamic load functions that represent the reaction for each restrained DOF then run them as dynamic loads. Risa allows you to have variable forcing functions over time.

JoshPlumSE (Structural) · Answer 5 · 2022-09-07 17:53:42

The Before You Begin section of the RISA help file should have information on program limitations. I just pulled up the on-line version and it suggested that the LC's are limited to 5000.

https://risa.com/risahelp/risa3d/index.htm#Common_...

Come Join Us!

Posting Guidelines

Max Number of Allowed Load Combinations?