For plant structures designed under Indian codes, the program calculates the seismic load per IS 1893 Part 1 Criteria for Earthquake Resistant Design of Structures, Part 1: General Provisions and Buildings, Fifth Revision (2002). A static, seismic base shear is calculated using the following general procedure and applied to top of the foundation.

1. Calculate Zone factor Z on the basis of 6.4.2 & Annex E or the mapped value.

   This can be directly specified or selected from a list of Indian cities.

2. Calculate Importance factor I on the basis of 6.4.2 & Table 6

3. Calculate Response Reduction factor R on the basis of 6.4.2 & Table 7

4. Calculate Sa/G from 6.4.2 & 6.4.5.

   This can be directly specified or can be calculated by the program based on code parameters.

5. Calculate Design Horizontal Seismic Coefficient Ah (Clause 6.4.2)

   $A_h=\frac{Z\times I{\times S}_a}{2R\times g}$

6. Calculate of building weight, W.

   Two conditions are considered by the program for each vessel: a) empty and b) operating. For vertical vessels,

7. Calculate Design Seismic Base Shear Vb (Clause 7.5.3)

   $V_b=A_h\times W$
   

   Base shears for vertical and horizontal vessels