The MCE_R spectral response acceleration parameters for short periods (S_MS), and at 1 s (S_M1), and, adjusted for Site Class effects, are determined by Eqs. 11.4-1 and 11.4-2, respectively.

•S_MS = FaS_S.......... Eq. 11.4-1

•S_M1 = FvS₁.......... Eq. 11.4-2

Site Coefficients (Fa and Fv)

The evaluation of the short-period site coefficient (F_a) and long-period site coefficient (Fv) depends on the Soil Site Class. The Site Coefficients F_a and F_v are obtained from tables 11.4-1 and 11.4-2. Check tables below. QuakeManager refers to the tables below to evaluate site coefficients. In case site classes or coefficients were unavailable, users may select Default Site Class "D"; however, F_a must be greater than 1.2.

In case the simplified design procedure of Section 12.14 is used, the value of Fa shall be determined in accordance with Section 12.14.8.1, and the values for Fv, S_MS, and S_M1 need not be determined.

The ground motion hazard analysis may be performed for the following cases:

•Seismic Isolated structures and structures with damping systems on sites with S₁ ≥ 0.6

•Structures on Site Class "E" with S_S ≥ 0.1

•Structures on Site Class "D" and "E" with S₁ ≥ 0.2

Table: Site Coefficient Fa (NEHRP 2015)

Table: Site Coefficient Fv (NEHRP 2015)

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