Natural Vibrations - 4
The Natural Frequency of a Building
The natural frequencies of vibration of a
building depend on its mass and its stiffness
(or how flexible it is).
The natural frequency for each mode
of vibration follows this rule:
= natural frequency in Hertz.
K = the
stiffness of the building associated with this mode
M = the
mass of the building associated with this mode
Buildings tend to have lower natural frequencies when they
- Either heavier (more mass)
- Or more flexible (that is less stiff).
One of the main things that affect the stiffness of a building
is its height. Taller buildings tend to be more flexible,
so they tend to have lower natural frequencies compared to
Try some simple experiments
with natural frequency.