Steel · Fire, corrosion & serviceability
Floor vibration from walking (AISC Design Guide 11) calculator
Natural frequency from the deflection of the floor system under its in-service weight, the predicted peak acceleration from walking and the comfort limit for the occupancy.
Standard: AISC DG11 (2nd ed.) · fn = 0.18√(g/Δ) · ap/g = P0·e^(−0.35fn)/(βW) ≤ limit
Inputs in the worked example
The live calculator starts with these values; change any of them and every result, check and diagram updates instantly.
| Input | Value | Unit |
|---|---|---|
| Beam deflection under in-service load | 6 | mm |
| Girder deflection under in-service load | 5 | mm |
| Effective panel weight W | 400 | kN |
| Damping ratio β | 0.03 office with ceiling and services | |
| Acceleration limit | 0.5 %g offices, residences | %g |
Worked example — results
| Result | Value | Unit |
|---|---|---|
| Combined deflection Δb + Δg | 11.00 | mm |
| Natural frequency 0.18√(g/Δ) | 5.38 | Hz |
| Peak acceleration 0.29e^(−0.35fn)/(βW) | 0.368 | %g |
- ✓ ap/g ≤ limit
- ✓ fn ≥ 3 Hz (avoid walking resonance)
Method, formulas and assumptions
- Combined deflection Δb + Δg = 6+5 = 11 mm
- Natural frequency 0.18√(g/Δ) = 0.18*SQRT(9810/11) = 5.3754 Hz
- Peak acceleration 0.29e^(−0.35fn)/(βW) = 0.29*EXP(-0.35*5.3754)/(0.03*400)*100 = 0.36825 %g
- W is the effective weight of the combined beam–girder panel mode (DG11 Ch. 4). For rhythmic activities or sensitive equipment use the specific DG11 chapters.
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For preliminary design and education. Check every result against the current standard and your own engineering judgement before use.