V_t : Horizontal Seismic Base Shear (see Fig. 2)

 A(T₁) : Spectral Acceleration Coefficient 

A (T) = A_O I S (T) 
A₀ : Effective Ground Acceleration Coefficient 
        from Table 1
I : Building Importance Factor from Table 2

S (T) : Spectrum Coefficient (see Fig. 1)

0 < T < T_A           S (T) = 1 + 1.5 T/T_A

T_A £ T £ T_B             S (T) = 2.5

T > T_B                  S (T) = 2.5 (T_B /T)^0.8

           T_{A &} T_B : given by Table 3
           If the equivalent seismic load method is applied, S (T) > or = 0.7.

R_a : Seismic Load Reduction Factor 

              0 < T < T_A             R_a = 1.5 + (R - 1.5) T/T _A 

              T > T_A                  R_a = R 

              R : Structural Behavior Factor from Table 4

W : Total weight of the building

wi : weight at level i, w _i = g _i + n q _i
g_i : total dead load at level i
q_i : total live load at level i
n : live load reduction factor from Table 5

Lateral force distribution along the height 

Lateral force to i-th story : 

where
                

               lateral force at N-th story = F_N + F_i

               hi : height from the base of the building at i-th story