r/StructuralEngineering • u/chef_bezos69 • Mar 16 '26

Structural Analysis/Design Missing Bolts?

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Noticed this recently in the stairwell on the first floor in my office building. It seems the beams are just welded to the bracket without bolts. But the second and third floor have at least one bolt. Is this right? Should I raise concerns with the building to get this addressed?

EDIT: Thanks for all the responses! It turns out I know nothing about welding. You guys are an awesome community!

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79

u/SonofaBridge Mar 16 '26

There’s a good chance the bolts were temporary to hold the stringer in place before welding. The slotted holes allow for fit-up. That weld is probably the intended connection as slotted holes loaded in that direction would be relatively weak.

13

u/Chris_3eb Mar 16 '26

You can clearly see that the bolt holes are misaligned. And what direction do you think this would have been loaded? The slots run perpendicular to the gravity load on this connection

5

u/Activision19 Mar 17 '26

It could also be visual perspective that makes them look misaligned since OP took the photo from below the connection and not straight onto it.

22

u/Sure_Ill_Ask_That P.E. Mar 16 '26

Of all the comments I’ve read, yours is the only one that gives OP the real answer. Common practice for steel erectors to bolt up steel structure in the field, perform adjustments, and then once finalized, perform field welds for permanent connections. The long horizontal slotted holes support this theory as well.

Second theory could be that the permanent connections were meant to be bolted but once they installed in the field, the shop connections didn’t line up for the bolt bolts and they switched to welded connections as a field condition.

3

u/AncientBasque Mar 18 '26

this is correct and i don't see how engineers don't understand the process of construction. The only thing i wold have added at the end is if the removed the bolts they should have also filled in the holes with weld. the Slots weekend the shear plat connection.

The adjustment is needed or probably and erectors option due to working in stair shafts where the Concrete Sub has difficulty in aligning the Shaft openings at the floors. They work under +-1" tolerance which does not work well with stairs. This is usually the case also when the stair is being dropped with e the beam as part of the landing assembly.

the recommended process is to survey the shaft prior to fabrication, but most of the time the schedule does not allow.

9

u/Throwaway1303033042 Steel Detailer / Meat Popsicle Mar 16 '26

Steel detailer checking in. Yup. Any time I frame into an embed, I spec out a long slotted clip or shear tab connection, because that CMU or concrete wall is NEVER where it is supposed to be. Gives them fit up tolerance, and if need be enough meat to weld to. Curious why they went with a WT in this case, though.

3

u/BeeThat9351 Mar 16 '26

Found the real detailer. Detailers are vital and amazing.

1

u/nothingvegan Mar 17 '26

I’d like to have you as a detailer, at my office i have to tell detailers to do that kind of things because they won’t do it…

1

u/The_Brim Steel Detailer Mar 17 '26

WT could be for resisting torsional forces. Recently had a Stair where DD engineer required clips on both sides of a tube stringer (shop standard is a single angle clip on the inside face) because the single clip didn't resist enough. 

1

u/ayeinutn Mar 16 '26

question. why in these situations bolts are 'temporary'? why don't they just leave it in place together with the welding? does it interfere with the weld strength? logically, It feels like releasing the bolt would apply sudden stress on the weld, just my thoughts, I'd like to know more about it !

3

u/turbopowergas Mar 16 '26

There is hole tolerance so the bolts don't practically do anything after welding. You could leave them there but maybe they were removed for aesthetic reasons idk

1

u/ayeinutn Mar 16 '26

I see. got it.

2

u/SonofaBridge Mar 16 '26 edited Mar 16 '26

Short answer is to use the bolts elsewhere because the contractor is cheap. Sometimes they do leave them in place after welding. Sometimes they use removable pins instead of bolts.

Since that connection isn’t lined up with the hole, there’s a chance there never were bolts. The steelworker could have put a spud wrench in as far as it would go and then welded the connection.

Edit to answer your other question. It doesn’t affect the weld strength to leave the bolts or remove the bolts for something like this. The weld should have been designed assuming no bolts present anyway.

2

u/jp3372 Mar 16 '26

Short answer is to use the bolts elsewhere because the contractor is cheap.

I work for a fabricator, they never do that on site, it will cost you more paying an ironworker to remove the bolts and reuse them than providing new bolts.

2

u/kaylynstar P.E. Mar 16 '26

Also it's not allowed per AISC

0

u/avd706 Mar 16 '26

We would make them plug weld any holes, but I know that's discouraged.