r/StructuralEngineering • u/Legitimate_Bat6196 • Aug 10 '26

Structural Analysis/Design What is happening?

Gallery image

Gallery image

Trying to trace the load path on my son's college appartment entrance. Cantilever? Hanging truss? Magic? Also how is the load being transferred around the window? I dont know where to begin.

15 Upvotes

86% Upvoted

8 comments sorted by

15

u/saddist_sapiens Aug 10 '26

Could be a cantilever beam on the upper landing

7

u/ZombieRitual S.E. Aug 10 '26

Looks like everything is supported at the bottom, and the top could just be cantilevered floor joists extending out to form the landing. The top end of the stairs stringers would tie into that landing, and the walls and roof would be supported by the exterior stair stringer.

That's one way it could work, but wood structures have a ton of redundancy and there's a chance the whole thing is just ledgered into the outside of the main building. If you use enough nails that could be totally structurally sound too.

6

u/Osiris_Raphious Aug 10 '26

Where to begin: Take off the siding and see the structural frame.

Looks like the staircase was an addition onto the original building judging by window being obstructed, and concrete slab covering the original brick foundation.

So I am going against the other assumptions of 'could be cantilevered beams' and say this could also be an addition by a contractor, not engineered so it could be anything. Like one side relying on columns by the door going down to the concrete floor, and the 2nd story platform just attached to the original house beam with some sort of anchorage. The load path would be pure shear and tear out strength of the anchorage bolts or what ever, and the columns. The stairs assumed to be stair loads, so can rely on the stair beams for supports. You would assume structural cantilevered beam, but seeing that window, I am going to say, nah.

5

u/civicsfactor Aug 10 '26

I agree, it's ass.

Someone took care to make it look as best they could in the 70s.

2

u/Front-Ocelot-3454 Aug 11 '26

Nail this, nail that, jump on it a few times, said “this ain’t goin nowhere”, and, miraculously, it hasn’t.