1613.3.3 Site Coefficients and Adjusted Maximum Considered Earthquake Spectral Response Acceleration Parameters

The maximum considered earthquake spectral response acceleration for short periods, S_MS, and at 1-second period, S_M1, adjusted for site class effects shall be determined by Equations 16-37 and 16-38, respectively:




where:

Fa	=	Site coefficient defined in Table 1613.3.3(1).
Fv	=	Site coefficient defined in Table 1613.3.3(2).
SS	=	The mapped spectral accelerations for short periods as determined in Section 1613.3.1.
S1	=	The mapped spectral accelerations for a 1-second period as determined in Section 1613.3.1.

TABLE 1613.3.3(1)
VALUES OF SITE COEFFICIENT F_a ^a

SITE CLASS	MAPPED SPECTRAL RESPONSE ACCELERATION AT SHORT PERIOD
	Ss ≤ 0.25	Ss = 0.50	Ss = 0.75	Ss = 1.00	Ss ≥ 1.25
A	0.8	0.8	0.8	0.8	0.8
B	1.0	1.0	1.0	1.0	1.0
C	1.2	1.2	1.1	1.0	1.0
D	1.6	1.4	1.2	1.1	1.0
E	2.5	1.7	1.2	0.9	0.9
F	Note b	Note b	Note b	Note b	Note b

1. Use straight-line interpolation for intermediate values of mapped spectral response acceleration at short period, S_s.
2. Values shall be determined in accordance with Section 11.4.7 of ASCE 7.

TABLE 1613.3.3(2)
VALUES OF SITE COEFFICIENT F_V ^a

SITE CLASS	MAPPED SPECTRAL RESPONSE ACCELERATION AT 1-SECOND PERIOD
	S1 ≤ 0.1	S1 = 0.2	S1 = 0.3	S1 = 0.4	S1 ≥ 0.5
A	0.8	0.8	0.8	0.8	0.8
B	1.0	1.0	1.0	1.0	1.0
C	1.7	1.6	1.5	1.4	1.3
D	2.4	2.0	1.8	1.6	1.5
E	3.5	3.2	2.8	2.4	2.4
F	Note b	Note b	Note b	Note b	Note b

1. Use straight-line interpolation for intermediate values of mapped spectral response acceleration at 1-second period, S₁.
2. Values shall be determined in accordance with Section 11.4.7 of ASCE 7.