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Code Name Indonesian Earthquake Code
Issued by Ministry of Public Works
Revision

Horizontal Base Shear


 where
    

Wt: Combination of the total vertical dead load and the reduced vertical live load

C: Basic seismic coefficient

(Note: This value shall be determined from Fig.1 for the seismic zones shown in Fig.2 using the structural period and the types of subsoil.)

I: Importance factor (See table 1)

K: Structure type factor (See table 2)

The types of subsoil
The types of subsoil are considered in selection of C firm and soft. For the purpose of this code a structure shall be considered as being on a soft subsoil if it is located on soil deposits exceeding the following depths.

For a cohesive soil with an average undrained shear strength not exceeding. 5kg per sq.cm. (50 kPa) :  6m

Any site where the overlying soils are either cohesive with an average undrained shear strength not exceeding 1kg per sq.ca. (100 kPa) or a very dense granular material : 9m

For a cohesive soil with an average undrained shear strength not exceeding 2kg per sq.cm. (200 kPa) : l2m

For a very dense cemented granular soil : 20mn

These provisions should apply regardless of whether there are piles extending to a deeper hard layer.

Depths shall be measured from the level at which the ground provides effective lateral restraint to the building.

For soils less deep than these limits the subsoil shall be considered as firm.