Castellated Beams 1

[SteelPE]

I was contacted by a fabricator recently in regards to helping them with some projects. The contact was actually someone I used to work with about 10 years ago and we have kept in touch periodically.

During our conversation he expressed concern in regards lead times for delivery of open-web steel joists. I had heard from a few clients that securing reasonable delivery times on open-web steel joists was becoming and issue with projects orders being placed now but not being delivered until late August. The conversation revolved around alternatives to open-web steel joists and was centered around castellated beams.

I know AISC has a design guide in relation to castellated beams. I also know that there used to be a company called SMI joists that used to produce castellated beams (I think they went out of business a few years ago). Has anyone used the castellated beam systems recently and do they know of any manufacturers in the United States/Canada?

 

[sbisteel]

Do a google search for "C-Beams", a fabricator in North Carolina supplies cellular and castellated beams. It's been a long while since I've looked into them, so they may or may not still be in that business.

I believe anyone can make castellated beams if you find a willing fabricator.

 

[SteelPE]

sbisteel

Yes, C-Beams did pop up in my search. I remember for a seminar years ago that the design process wasn't very easy and that it would lend itself to being similar to a joist manufacturer. The fabricator is willing to fabricate themselves, but I am not exactly willing to design them at this time (as AISC DG 31 is quite lengthy). I am hopping to point client in the direction of a fabricator similar to C-Beam/New Millennium/Vulcraft etc.

 

[sbisteel]

I believe RAM Structural system will design castellated beams (same goes for the SBeam module).

If the folks at C-Beam are not around, I doubt there are any American vendors left. Next bet would be Arcelormittal's ACB & Angelina products. With the current lead times for joist & deck, it might actually work out.

 

[dik]

Although a bit dated, Blodgett has a bit of a write up on them.

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

 

[Kennylie]

ETABS can design castellated beam according AISC DG 31 and from my experience their castellated design module is pretty robust

 

[SteelPE]

I do have RAM Structural System and I was able to find them under the term C-Beam (I always thought they were SMI joists or something like that). I did talk to the fabricator late again yesterday telling him the process and what the rough results were from a RAM analysis. I have him a steel joist size, castellated beam size and regular beam size so he could see what the cost difference was between all of them.

For a point of reference here is what RAM spit out for a 40' long beam @ 5'-0" o.c. with 55 psf loading.

26K7 @ 9 lbs/ft
18CB16 C= 3/4" (which I think is a W12x16 made to be 18" deep)
W14x22 C= 3/4"

(FYI, these are coming from memory so they may not be exact).

The @40' a W14x22 seems a bit small, but it's just the raw sizes RAM spit out.

So for a small savings in weight you have a lot of work to do to split the beams and weld them back together.

I would assume if you decided to use a castellated beam there would be a manufacturer involved that knew more about their design and that this sizing exercise was only for comparison purposes

 

[phamENG]

SteelPE - was that just considering strength? From a stiffness/deflection perspective, you get a pretty nice increase for that weight reduction.

A 14" beam seems awfully shallow for 40'. Even on a roof, I'd expect something closer to an 18" or 20". 24" if you're looking at floor loading.

 

[SteelPE]

I didn't like the 14" beam spanning 40' on this roof either. This is what RAM spit out for answers.... and it should have taken into account strength and stiffness/deflection.

I didn't check it, as we were just running a quick exercise to see what the costs difference would be between the different systems.

I foresee this material crunch as being a huge thorn in my side over the next couple of months. I gave a proposal to a very good client a few months ago regarding the design of a 600,000 square foot single story building (warehouse/production). If things are not resolved (and they probably won't be) and we can't come up with a viable solution, that project is going to get tabled even before it's started.