Foundation Settlement Differential Calculator

Calculate differential settlement between two foundation points, angular distortion, and evaluate against allowable limits per structural guidelines.

Settlement at Point A, S₁ (mm) Settlement at Point B, S₂ (mm) Distance Between Points, L (m)

Structure Type Custom Angular Distortion Limit (1/N) Maximum Allowable Differential Settlement (mm)

Differential Settlement:
ΔS = |S₁ − S₂|

Angular Distortion:
β = ΔS / L
where ΔS is in mm and L is in mm (consistent units).

Utilisation Ratio:
U = β / β_allow × 100%

Tilt Angle:
θ = arctan(β) in degrees

Angular distortion limits are based on Skempton & MacDonald (1956) and Bjerrum (1963).
Steel frame limit (1/300): onset of cracking in panel walls (Bjerrum, 1963).
RC frame limit (1/400): structural damage threshold (IS 1904, Eurocode 7).
Load-bearing masonry limit (1/500): cracking in load-bearing walls (Skempton & MacDonald).
Sensitive machinery / high-rise limit (1/750): strict operational requirements.
Settlement values represent total (final) settlement at each point.
The method assumes linear variation of settlement between the two points.
Differential settlement limits may also be governed by serviceability requirements per Eurocode 7 (EN 1997-1) or local codes.
This calculator does not account for time-dependent (consolidation) effects or soil layering.

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