SYMBOLS
SD1 = Long period design spectral response acceleration parameter for 1 s
SDS = Short period design spectral response acceleration parameter
Structures are categorized to a Seismic Design Category according to their Risk Category and the design spectral response acceleration parameters, SDS and SD1, with Table 11.6-1 or 11.6-2.
SDS | I or II or III | IV |
|---|---|---|
SDS < 0.167 | A | A |
0.167 ≤ SDS < 0.33 | B | C |
0.33 ≤ SDS < 0.50 | C | D |
0.50 ≤ SDS | D | D |
SD1 | I or II or III | IV |
|---|---|---|
SDS < 0.067 | A | A |
0.067 ≤ SDS < 0.133 | B | C |
0.133 ≤ SDS < 0.20 | C | D |
0.20 ≤ SDS | D | D |
Risk Category I, II, or III structures settled where SD1 is greater than or equal to 0.75, is designated to Seismic Design Category E. Risk Category IV structures settled where SD1 is greater than or equal to 0.75, is designated to Seismic Design Category F.