damped spectral response seism.

[sevkevich]

Пожалуйста, помогите прояснить выражение: damped spectral response (интересует последний абзац).
Встречается в американских строительных нормах:

Expected loads. Structures shall be designed and constructed taking into account all expected loads associated with the event(s)... that would affect their performance, including:
... Earthquake loads (mean return period)
... Very Large: 2,475 years.
At sites where the 2475 year, 5-percent damped spectral response acceleration at a 0.3-second period exceeds 1.5 g and at a 1-second period exceeds 0.6 g, Very Large ground shaking demands need not exceed a 5-percent damped response spectrum that at each period is 150 percent of the median spectral response acceleration ordinate resulting from a characteristic earthquake on any known active fault in the region.
Спасибо!

[Igor Kravchenko-Berezhnoy]

5-percent damped spectral response acceleration - ускорения толчка со спектром, демпфированным на 5%