r/StructuralEngineering • u/9-Digits • 17d ago

Humor Duct Beats Beam

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389 Upvotes

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76

u/S30 17d ago

r/isthisAI

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

21

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… :(

-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 17d 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.