Effective Slenderness Ratio (RISA vs STAAD) 1

[ads0221]

I'm modeling a small elevated platform for a client and I came across something I wanted to get some clarity. Lets say you have a simple C6x8.2 Channel braced at each end and 12ft long. Why is it that STAAD flags the channel for slenderness and RISA under the same conditions doesn't? Is my understanding that the L/r ratio < 200 compression and < 300 tension is more so a recommendation? (All loads are extremely light). Normally I wouldn't find a work around but we're trying to get around needing to make retofits to this platform because it would be elevated work.

Any thoughts?

 

[JoshPlumSE]

It's one of two thing:

1) Something is different. K, L or R. If the two programs are calculating different slenderness ratios. Then you probably have to look at your input and what you've entered.

2) I believe RISA has a user option for AISC about whether or not the program will flag KL/r ratios greater than 200. If I remember correctly, this is an AISC recommendation, but not a requirement.

 

[ads0221]

That’s what I’m thinking. I’m going to make a model side by side as a test to make sure.


Correct.

Thanks for your reply!