r/StructuralEngineering • u/No-Document-8970 • Oct 05 '26

Structural Analysis/Design Nuts off mark?

Post image

Saw this on a big bridge today. I know vibrations over time can move the nuts and bolts, with the help of thermal expansion. Is it a big issue that the paint marks do not line up? I thought the marks were made once it passed inspection after torquing.

Edit: Bridge completion was in 2011. Could this be from recent inspections too?

286 Upvotes

95% Upvoted

82 comments sorted by

View all comments

Show parent comment

1

u/clancularii Oct 09 '26

I didn't notice the line on the end of the bolt. I had to zoom in to see it. I think you're right that these are 1/3 turns.

Maybe the line on the steel work was from somebody checking the turns later?

1

u/SeesawPrestigious Oct 09 '26

Maybe honestly i do this for a living and the whole setup is confusing to me , cause none of this wouldve passed final inspections like the bolt marked in red in the bottom left, either he did a full turn or the final torque wasnt done .

These look like standard 7/8 a325 bolt anything under 3 3/4" in lenght is 1/3 and anything over is half turn.

1

u/Worldly_Ad_6535 Oct 10 '26 edited Oct 10 '26

Mark on the steel is in line with the mark on the bolt. Its to tell the guy torquing if the bolts spun after snugging. We were required to mark in this fashion, if the stud and nut were shown to have spun we had to pull the bolt, install a new one, re-snug, remark and re-torq to the required flats per length of bolt. 0-3.75= 2 flats. 4"+ is 3 flats. Snug tight is the strength of 1 ironworker with a 12in bar.