Floor Vibrations

Human activities like walking, dancing or running may generate frequency acting forces in a construction.

The frequencies are in general in the range 1.0 to 3.0 Hz (1/s) - normally below the most common resonance frequencies for floor constructions.

Typical resonate frequencies in wooden beam floors are

• Joist span 3 m : 12 Hz
• Joist span 6 m : 9 Hz
• Joist span 9 m : 7 Hz
• Joist span 12 m : 6 Hz
• Joist span 18 m : 5 Hz

Resonate frequencies in concrete floors on the ground depends on the materials in the ground below. Typical resonate frequencies ranges 10 - 100 Hz: 

• Sand : 15 - 25 Hz
• Clay, wet : 15 Hz
• Clay, hard : 30 Hz
• Gravel : 20 - 25 Hz
• Limestone : 35 - 45 Hz
• Solid rock : 40 - 50 Hz

Example - Running Cadence

The force frequency - f  - for a "everyday" runner with cadence 150 steps pr. minute can be calculated

f = (150 1/min) (1 / 60 min/s)

  = 2.5 (1/s, Hz)

The force frequency - f  - for a "elite" runner with cadence 200 steps pr. minute can be calculated

f = (200 1/min) (1 / 60 min/s)

  = 3.3 (1/s, Hz)