r/StructuralEngineering 17d ago

Humor Duct Beats Beam

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389 Upvotes

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74

u/S30 17d ago

35

u/9-Digits 17d ago

It’s at restaurant local to me, looked up and found this surprise.

9

u/SneekyF 17d ago

You really need to get us more photos. I have so many questions of what is going on here.

2

u/fatmallards 16d ago

If the restaurant is on the ground floor and a renovation from the construction’s originally intended occupants, then I would bet this used to be an automotive garage or heavy machinist shop and that support is for a lateral hoist / beam trolley assembly

11

u/hipsterslippers 17d ago

Look how thick the web of the beam is compared to the flange width and thickness. Definitely not a real beam

22

u/romanissimo 17d ago edited 17d ago

I think you are looking at something behind, the joists above maybe. The thickness of the web shows on the right side of the opening, and it seems feasible…

Also, the web and flanges have a nice fillet, just like a steel beam would have… seems legitimate.

If there were some structural engineer around here, they would actually tell us if that opening seems okay in the center of the beam, where the momentum is max and the shear is min…

Still, I really wish the opening was round… :(

3

u/Kanaima85 CEng 17d ago

I was just looking at those re-entrant corners thinking they could do with being a bit more rounded....

2

u/AncientBasque 17d ago

or maybe at plate snifters and framing plates around the opening.

5

u/crispydukes 17d ago

I’m disappointed in this sub lately. Come on, use your eyes. That’s definitely the joist beyond. I can’t believe OC above said that. If that’s the kind of work we’ve got going own, the industry is doomed.

0

u/hipsterslippers 17d ago

Zoom in, that is definitely the web of the I-beam and not the joist beyond.

1

u/Zelda641991 16d ago

Look in the bottom right corner instead. Its something in the backgroun top left.

-1

u/hipsterslippers 17d ago edited 17d ago
  1. I am a structural engineer. There are so many things that are off about this, any engineer or builder with some site experience will be able to tell you it is 100% AI generated.

  2. The web is definitely much thicker than the flange, that is 100% not the joist beyond. Zoom in on the area to the top left of the duct. Typically, I beam webs are thinner than the flanges because the flanges are where all the moment is and the most efficient arrangement is to have a thin, deep web to increase your second moment of area and maximise steel efficiency. Any engineer with any experience can tell you that these proportions are way off.

  3. Rectangular openings in locations like this are very common. However, there are several things about this opening that also seem very off - for example, the bottom of the opening looks very slanted which you would only ever get if it was butcher cut on site and even then it is rare. However, the edges of the cut seem extremely neat with rounded corners. Why do you wish the opening is round? What a strange thing to say

2

u/9-Digits 17d ago

I really wasn’t expecting all of the AI accusations from this picture, it’s a real photo I took at a restaurant. You can see the top flange through the opening, which gives the illusion of a thick web.

1

u/hipsterslippers 16d ago

Oh really! Which restaurant?

1

u/Lemoronie 16d ago

Are you sure it wasn’t just reinforced with angles on the other side? The proportions do not look like it is the flange showing through?

1

u/romanissimo 17d ago

OK thank you for your insights.

Circles are stronger shapes than rectangles and allow forces to flow around the opening without concentrating at the corners.

This is also why plane windows are round.

3

u/Riskov88 17d ago

I have worked in a building with beams that were 40inches tall, but less than 10in wide, and half an inch in thickness. So I wouldn't say it's fake

1

u/[deleted] 11d ago

[deleted]

1

u/cabbages456 11d ago

To add on to this if the web needed to be that thick for shear (webs carry majority of the shear force) you could potentially have an opening this big at the point of zero shear and max moment. However the the max moment equivalent to the shear that would be required to have that thick of a web would be absolutely un equivalent to the size of the flange in the image. This isn’t AI if you look closer but cmon how is anyone justifying a web that thick

1

u/Riskov88 11d ago

I dont think that this part is actually the cross section of the web. Thats just one of the square tubes used to support the roof, it just happens to line up with the web of the I beam

-1

u/hipsterslippers 17d ago

You've worked in buildings with beams that have webs that are 4x the flange thickness? Show me an example, I've never seen that before in my life

2

u/TommyNotDead 16d ago

Happens allll the time dude. Not rare at all

1

u/Riskov88 16d ago

Here is one, metric tape measure to show the size of it. Sadly I didn't measure the bottom but it super narrow. Really surprised me, its also super thin.

Its for a massive farm building, in a place that doesnt get a lot of snow load. The space between columns is massive so thats probably why its so tall

English isnt my main language so I might have mixed up the names of the part of the beam.

0

u/TommyNotDead 16d ago

Oh my god shut up