Spectral acceleration

Spectral acceleration (SA) is a unit measured in g (the acceleration due to <a href="/facts/Earth%2527s_gravity/IXe9Bh8k">Earth's gravity</a>, equivalent to <a href="/facts/G-force/F5j4of9l">g-force</a>) that describes the maximum acceleration in an <a href="/facts/Earthquake/NGjIzagw">earthquake</a> on an object – specifically a damped, <a href="/facts/Harmonic_oscillator/7IQNToGt">harmonic oscillator</a> moving in one physical <a href="/facts/Dimension/0ktmUyac">dimension</a>. This can be measured at (or specified for) different oscillation <a href="/facts/Frequency/QUSbPaW8">frequencies</a> and with different degrees of <a href="/facts/Damping_ratio/UW3RsjEd">damping</a>, although 5% damping is commonly applied. The SA at different frequencies may be plotted to form a <a href="/facts/Response_spectrum/00leyG7f">response spectrum</a>.
Spectral acceleration, with a value related to the <a href="/facts/Mechanical_resonance/auGLdfCa">natural frequency of vibration</a> of the building, is used in <a href="/facts/Earthquake_engineering/rF0Yv7co">earthquake engineering</a> and gives a closer approximation to the motion of a building or other structure in an earthquake than the <a href="/facts/Peak_ground_acceleration/SjVGYxrF">peak ground acceleration</a> value, although there is normally a <a href="/facts/Correlation_and_dependence/egkluAEm">correlation</a> between [short period] SA and PGA.
Some <a href="/facts/Seismic_hazard/0ssayKA9">seismic hazard</a> maps are also produced using spectral acceleration.

Spectral acceleration open-in-new

Spectral acceleration