For the computation of CRR , Cortè proposes two relationships function of the parameter D50:
•for soils with 0,04 mm ≤ D50 ≤ 0,6:
•for soils with 0,6 mm ≤ D50 ≤ 1,5:
The coefficient A takes values that vary between 0.50 and 0.66, depending on the magnitude of the earthquake and on the number of equivalent cycles that vary at their turn between 5 and 20.
CSR is calculated using the expression developed by Seed and Idriss (1971-1982) where the reduction factor rd is determined using the empirical formula proposed by Iwasaki et al. (1978)
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