When you’re on a site walk and have to decide if a beam warrants a full analysis, what’s your practical tripwire? I tend to flag anything worse than L/360 under an estimated 60 psf live load and follow with dial indicators for 24 hours to check elastic recovery, but I’m curious where others draw the line on serviceability versus load-bearing risk in existing office frames.
But > 24 hours to check elastic recovery, but I’m curious where others draw the line on serviceability — Same here; I’ll push to 48 hours if loads are noisy and add a phone vib check: if the bay’s f_n is under about 8 Hz or about 30% below expected for the span/section, it’s a full analysis. For geometry, my tripwire is residual midspan > L/1000 after a light unload or <80% recovery from a 5–10 psf test stack; do you count heavy partitions in your 60 psf or treat them as dead?
I use slope as a quick proxy: if midspan slope is steeper than about 1/500 or deflection is past L/480 under a rough 60 psf, I tag it for shoring and a calc. If “residual deflection” after a controlled unload is >15–20% of peak, I assume stiffness loss and dig into composite action and bearing length. If it feels like a slow-motion diving board under a heel‑to‑toe walk, it usually is.