Seismic Analysis — Equivalent Static Method
As per IS 1893 (Part 1) : 2016 | Clause 6.4, 7.6 | Table 2, 6, 7, 8
Ah = (Z/2) × (I/R) × (Sa/g)
Av = (2/3) × Ah
1. Seismic Parameters
Seismic Zone (Table 2)
Z = 0.24
Importance Factor — I (Table 8)
I = 1.0
Structural System / Response Reduction Factor R (Table 9)
R = 5
Damping Ratio (Cl. 6.4.5)
×1.00
Site Soil Type (Table 1)
Type II
2. Fundamental Time Period (T)
Structure Type for Ta
Height of Building (h)
m
Calculated Ta (codal)
sec
Note: As per IS 1893:2016 Cl. 7.6.2 — Ta from 3D analysis should not exceed 1.25× the codal value for regular buildings.
Time Period T (from software / analysis)
sec
Note: T entered manually from 3D model / dynamic analysis. Ensure compliance with Cl. 7.6.2 cap if applicable.
3. Results
Zone Factor (Z)
Importance Factor (I)
Response Reduction Factor (R)
Damping Multiplier (η)
Design Time Period (T)
sec
Spectral Acceleration Coefficient (Sa/g) for selected soil
Design Horizontal Seismic Coefficient
—
Ah = (Z/2)×(I/R)×(Sa/g)
Design Vertical Seismic Coefficient
—
Av = (2/3) × Ah
Design Horizontal Seismic Coefficient (Ah)
Design Vertical Seismic Coefficient (Av)
Ah at same T for all Soil Types:
Ah — Type I (Rock)
Ah — Type II (Medium soil)
Ah — Type III (Soft soil)
4. Response Spectrum — Sa/g vs T (IS 1893:2016, Table 8)
Curves shown at selected damping ratio. Vertical marker = design time period T. Shaded region = plateau (peak spectral acceleration).
5. Ah vs T — All Soil Types
Ah curves for Zone, I, R, damping selected above. Vertical marker = design T.