IS 1893 (Part 1): 2025 — Updated Site Classes & Return Periods
Modal Analysis Mode
Provide storey masses (kg or kN/g), lateral stiffness (kN/m), and heights for eigenvalue-based response spectrum analysis per IS 1893:2025.
Enter parameters and click Calculate to see results.
Base Shear Results IS 1893:2025
Zone Factor (Z)
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Ah (Sa/g)
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Hor. Acc. Coefficient
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Base Shear V (kN)
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Lateral Storey Force
Optional: Calculate floor-by-floor lateral force distribution.