UFC 4-152-01
28 July 2005
3-4.5.3
Performance Based Seismic Design Provisions.
a. Earthquake Loads: Follow the provisions of Marine Oil Terminal
Engineering and Maintenance Standards, Section 3.4. The spectral
acceleration values for earthquakes with a 2 and 10 percent probability of
exceedance in a 50-year period are typically well defined. To obtain seismic
spectral accelerations for other recurrence intervals use the following formula
based upon the procedure presented in Section 1.6.1.3 of Prestandard and
Commentary for the Seismic Rehabilitation of Buildings.
Equation 3-1
Si = Si(10/50) (Ci),
where:
Si
= Spectral acceleration parameter("i" = "s" for short-period, or "i" = "1" for 1
second period)
second period) at a 10% probability of exceedance in 50 years
= Modifier provided in Tables 3-4 and 3-5 below("i" = "s" for short-period, or
Ci
"i" = "1" for 1 second period).
Table 3-4 Values of CS, modifier for short-period spectral acceleration
Design Earthquake Probability of Exceedance in 50 Years
Region
10 %
15 %
20 %
50 %
65 %
75 %
California
1.0
0.83
0.72
0.44
0.36
0.32
Pacific
1.0
0.79
0.67
0.36
0.29
0.25
Northwest
Eastern US
1.0
0.72
0.56
0.23
0.17
0.14
Other locations
1.0
0.79
0.67
0.36
0.29
0.25
Notes:
1. The modifier Cs includes a statistical adjustment factor, "PR ", and a location adjustment factor, "n",
as defined in section 1.6.1.3 in Prestandard and Commentary for the Seismic Rehabilitation of
Buildings, Nov. 2000, FEMA-356. The value of "n" is taken as 0.54 for locations outside of the
continental US.
2. This table is valid at locations where the Mapped MCE spectral acceleration for short-periods, SS,
is less than 1.5g.
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