1613.3.3 Site coefficients and adjusted maximum considered earthquake spectral response acceleration parameters.
BC § 1613.3.3
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 16-44 and 16-45, respectively: SMS = FaSs (Equation 16-44) SM1 = FvS1 (Equation 16-45) where: Fa = Site coefficient defined in Table 1613.3.3(1). Fv = Site coefficient defined in Table 1613.3.3(2). Ss = The mapped MCER spectral accelerations for short periods as determined in Section 1613.3.1. S1 = The mapped MCER spectral accelerations for a 1-s period as determined in Section 1613.3.1. Exception: When electronic values of mapped acceleration parameters are used as per Section 1613.3.1 of this code, the site coefficients, F a and F v , cannot be taken from Tables 1613.3.3(1) and 1613.3.3(2) of this code. Rather, general procedures in Chapter 11 of ASCE 7 shall be followed to determine F a and F v . Table 1613.3.3(1)Values of Site Coefficient Fa as a Function of Site Class and Mapped Spectral Response Acceleration at Short Periods (SS) a Site Class FaSite Class FaA 0.80 B (V s measured)0.90B (V s unmeasured)1.00 C 1.30 D 1.57 E 2.28 F Note a a. Site-specific geotechnical investigation and dynamic site response analyses shall be performed to determine appropriate values, except that for structures with periods of vibration equal or less than 0.5 second, values of Fa for liquefiable soils are permitted to be taken equal to the values for the site class determined without regard to liquefaction in Section 1613.3.4.1. Table 1613.3.3(2)Values of Site Coefficient Fv as a Function of Site Class and Mapped Spectral Response Acceleration at 1-Second Period (S1) a Site Class Fv Site Class Fv A 0.80 B (V s measured)0.90B (V s unmeasured)1.00 C 1.50 D 2.40 E 4.20 F Note a a. Site-specific geotechnical investigation and dynamic site response analyses shall be performed to determine appropriate values, except that for structures with periods of vibration equal or less than 0.5 second, values of Fv for liquefiable soils are permitted to be taken equal to the values for the site class determined without regard to liquefaction in Section 1613.3.4.1.
