E_h,i = K_Ei × G_i

E_h,i : Holizontal earthquake force at the i-th story.

G_i : Total weight of the mass in the i-th story.

       G_i = G_G,i + K_o × G_Z,i

       G_G,i : weight of the structural parts and unremovable furnishings in the i-th story.

       G_Z,i : Live, temporal vertical load in the i-th story.

       K_o = Coefficient as a function of building use (see Table 1)

K_Ei = Determined by the following equation.

      K_Ei = ε × K₁ × K₂ × K_3i × K₄

        ε = Seismic zone factor (no information on zone map)

       K₁ : Ground condition and foundation type factor (see Table 2)

       K₂ : Structural behavior factor

             K₂ = 6T + 1         for 0.0s ≦ T ≦ 0.1s

             K₂ = 1.6               for 0.1s < T ≦ 0.5s

             K₂ = 0.8 / T          for 0.5s < T ≦ 1.0s

             T = Natural period of the structure

      K_zi = factor varying along building height

              K_zi = h_i / h       0 ≦ h_i / h ≦ 1

      h_i : Height of the i-th story floor

      K₄ : Importance factor (see Table 3)