where:
Z = zoning coefficient according to Table 1
U = factor of importance and use given in Table 1
S = soil factor given in Table 2
C = seismic coefficient according to Table 3
R = reduction coefficient given in Table 4
P = weight of the structure according to Table5

Table 1 
Zoning Coefficient (Z)
It depends of the seismic zone where the building is located.

Factor "Z" 

                   
Factor of Importance and Use(U).- It depends on the building category.

Factor "U"  

Structure type "D" is exonerated of seismic force analysis, but they should provide adequate resistance and stiffness for lateral actions.

Table 2
Soil Factor (S)
This factor consider the amplification of the earthquake effect, according to the characteristics  of the sub-soil. It must be considered a depth of 1/2 of the shorter dimension of the building's base depending on its bearing capacity. The S values are refered to the behavior of the structure over hard layer.

Table 3 
Seismic Coefficient (C)
t shall be calculated by the response acceleration spectra, generalized in the following formula:

where:
T = fundamental period of the structure
T_p = predominant period of the soil

Table 4 
Reduction Factor (R)

(1) At least the 80% of the base shear acts on the columns that fulfilled with the requirements of the Reinforced Concrete Code NTE E.060. In case it has structural walls, these should be designed to resist a fraction of the total seismic force in accordance with its stiffness.

(2) The seismic forces are resisted by a combination of structural walls and frames. Frames must be designed to take at least 25% of the shear force at the base. Structural walls will be designed for the forces obtained in the analysis indicated in item 4.1.2

(3) System where the seismic resistance is hold by structural walls which support at least the 80% of the base shear.

(4) Low height story edification with high density of limited ductility walls.

(5) For allowable stresses design the R values must be 6.

(*)  These coefficients will apply only to structures where the vertical and horizontal elements allow energy dissipation maintaining the stability of the structure.  It doesn’t apply to invert pendulum type structures.

(**) For irregular structures, the values for R should be taken as ¾ of those indicated in the table. For ground structures refer to the Adobe Code NTE E.080.         These types of constructions are not recommended in soils S3 nor are permitted in soils S4.

Table 5 
Weight of the Building (P)

The weight "P" must be calculated adding the dead and permanent load of the building to a percentage of the live load which can be determined as follows: