Lateral bracing to existing steel beam

[ajk1]

I am designing lateral bracing to several existing steel beams that were installed many years ago, at the underside of a waffle slab. Attached are 2 options, but both require a fair amount of field welding which is expensive and time consuming. The first option probably does not work because the minimum required concrete thickness for the KWIK bolt is 3" and the waffle slab is only 2½" thick (although perhaps the topping could be considered as adding to the slab thickness, but probably not prudent to do so).

Does anyone have any ideas for a better brace, with less field welding? Note that the position of the steel beam varies relative to the rib of the waffle, but it never is directly under the rib.

 

[bowlingdanish]

I feel dumb. Why has no one asked why the beam needs new lateral braces, and for what purpose? Is there additional load being added? Why didn't the beams have this in the first place? What is the beam even supporting and how does everyone seem to know all of these things given no information? If it's for LTB it only needs 5%ish of the flange compression so im sure you could get a fixing to work within the slab comfortably. I'll leave now

 

[KootK]

No need to feel dumb. ajk1 will tend to split his questions up into logical chunks with each being a seperate thread. So, sometimes, there's some backstory to be had elsewhere. For example, we previously discussed whether or not the grout connection alone would be capable of bracing the beam which was, in all likelihood, the original designer's assumption. Beyond that, if ajk1 tell me that his beam requires some LTB bracing, I simply take him at his word.

One of the thinks that I enjoy about ajk1's threads is that the crux of them usually revolves around coming up with a creative, build-able detail for a tricky renovation situation. They're like clean little homework problems where you don't need to bother with any math. Plus you get to do some drawing and compare your answers with the other kids.

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.

 

[bowlingdanish]

Oh well that's a relief

coming up with a creative, build-able detail for a tricky renovation situation.

heh well it'll be hard to top bolting on two 1/2 HSS sections to prevent LTB

 

[KootK]

heh well it'll be hard to top bolting on two 1/2 HSS sections to prevent LTB pipe

Right? And you'll notice that, despite that solution being whacky and an unlikely final choice, ajk's still willing to give it some legitimate consideration. Safe space -- I love it. And, one time in ten, that whacky solution winds up being the dark horse best solution.

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.

 

[ajk1]

Kootk has beaten me to it with the answer and managed some very kind words for me in the process. So thanks to BowlingDanish for giving Kootk the opportunity to be so kind. Basically it was designed without lateral bracing, but the engineer who designed it 20 years ago now agrees with me that it should have lateral bracing. The whole issue was triggered during current garage repairs when I was reviewing the effect of the mastic traffic topping weight and whether the designer of the steel beams would have included that weight when he designed the steel beams in the 1990's, since the mastic was not indicated on the original 1956 drawings, and was added some time after the original construction. Now please don't ask me why the steel beams are there. If I give the whole background I will spend an awful lot of time of peripheral issues, though I do appreciate your comments.