A beam – maybe steel, maybe wrought iron – in a sidewalk vault, photographed several years ago:
Just to be clear about what you’re looking at:
A is some white paint (almost certainly lead-based) on the beam web. B is a big hole where the web has rusted away completely. C is what’s left of the bottom flange after a lot of delamination and other material loss. D is what’s left of the top flange, ditto.
Note that the beam has not collapsed or even deflected much despite its rather obvious problems. That doesn’t mean that it’s okay…and it doesn’t mean that it’s not okay. The beams are a mid-span support for the big stone slabs that make up the sidewalk (and which are not waterproof, hence the problems that the beam is having.) Maybe the slabs can span without the beam. Maybe they can’t but the sidewalk has never seen any vehicular live load, only lighter pedestrian live load.
There’s always the extra-credit problem: is the beam stiff enough to actually carry a significant amount of the load? The stone slabs will deflect very little before failure, and the only way for load to get to the beam1 is through the slabs deflecting. So this beam may literally have never been loaded in any meaningful way.
- There’s some hatch framing on the far left, and there would be some load transferred there. I’m talking about the typical condition. ↩︎
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