Steel: Castellated Beams

So I thought I'd give you a brief overview of castellated steel beams. It was used extensively with the high-tech movement, including, for example, Norman Foster's Renault factory in Swindon in the UK. They had these castellated beams. Also, the Corning Museum in upstate New York in Corning by Smith Miller Hawkinson. And it's basically these beams with holes in them. The same is true for the High Museum Edition by Renzo Piano Building Workshop of 2005. Anyway, so let's talk a little bit about these castellated beams. Oh, here are some examples that are not as pretty. For example, in this case, we have hexagonal openings, we have round openings over here. So these are usually used in industrial facilities or parking, as we see over here, parking decks. Okay, so what happens with a castellated beam is you take a beam of a certain depth and you cut a certain pattern, either this trapezoidal pattern or else this pattern of semicircles, straight, semicircles, straight, and you cut the beam in two halves, and then you shift it. You shift the two halves with respect to each other, and you get a beam which is almost twice as deep as the original beam for the same material. And there is no material at the neutral axis. Right here, there's no material. And we can run our ducts, our pipes, all that stuff. If you remember from your structures courses, if you have a simply supported beam and you load it, then it typically does something like that with the top going in compression and the bottom going in tension. So there's stress on the top, there's stress on the bottom, but the neutral axis does not have any tensile stress or compressive stress. Therefore, it's okay to remove material from the middle and to run some ducts, pipes, ducts, etc. So a castellated beam, this image illustrates it better, where you take two halves, you shift them, and then re-weld. So that's the castellated beam, and this beam is much deeper, almost twice as deep as the original beam. So the way this is done is with typically a plasma cutting torch, CNC controlled and goes in and cuts the pattern. And then here we are with, oops, here we are with two halves. And this is one half, this is the other half. And then they shift them so that the straight lands on the straight and then the two circles will match. And then they re-weld it. So here it is, re-welded with no material at the neutral axis. Typically, these guys are good for a span range of, it doesn't make sense to use them for less than 30 feet because there's a lot more economical options. So typically between 30 and 100 feet, but the most economical range is around 70 feet, which makes it ideal for parking, industrial, etc. And the span to depth ratio is around 15 for a rule of thumb. So, if I would like to span 60 feet, I can divide by 15 and get an approximate depth of 4 feet. Also, these openings, let's go to the next slide. Here's a trapezoidal cut, And then it's shifted. And then it's welded back again. And this opening could be as much as 75% of the original depth. Oops, I went to the next beam here. I meant to here. I'm sorry about that. Okay. So, that's a pretty large opening that you can run a lot of stuff through for construction. I hope this was useful. you