A structural or foundation failure mode in which a body rotates about an edge or pivot (base) because destabilizing moments exceed the resisting (stabilizing) moments about the same point, often manifested by uplift at one edge, loss of bearing, or progressive rotation leading to loss of stability or collapse.

Principle

Rotational equilibrium about a chosen pivot governs stability; overturning occurs when the sum of external destabilizing moments (from lateral loads, eccentric vertical loads, earth pressures, etc.) exceeds the resisting moments provided by weights, anchorage, passive earth resistance and other stabilizing effects, typically evaluated with a factor of safety.

Demonstration

Illustrative scenario → A cantilever retaining wall under increasing lateral earth pressure: recognition → compute moment of earth pressure about the toe and resisting moment due to wall weight and soil on the heel; action → if destabilizing moment exceeds resisting moment the wall begins to rotate about the toe; consequence → uplift at the heel, decreased contact pressure distribution, progressive rotation and possible collapse unless restrained or remedied.

Misapplication

Assuming zero net moment about an arbitrary point guarantees safety without checking contact pressure distribution, uplift, or center‑of‑pressure position; the error is treating scalar moment balance in isolation from bearing and uplift effects that change the true resisting capacity.

Consequence

Overturning leads to redistribution or loss of bearing pressures, uplift of one edge, large rotations and often progressive failure of structural or geotechnical systems; prior detection can permit mitigation (anchors, increased base width, reducing loads), while late detection risks sudden loss of service or collapse.

Reversal

If sufficient passive resistance, external anchorage, or tensile elements (anchors, piles) are present, rotation can be arrested even when simple moment comparison would predict overturning; conversely, ductile structural rotation capacity can permit safe redistribution of moments beyond rigid‑body overturning checks.

Boundary

Clearly within → rigid‑body rotation about the base edge or pivot leading to uplift. Boundary case → combined sliding and overturning where both mechanisms interact. Clearly outside → material failure by local yielding without appreciable rigid‑body rotation (pure flexural failure internal to the structure).

Semantic Tension

Global stability criterion (prevent overturning) ↔ serviceability and acceptable rotation (small rotations may be tolerable); design must balance safety against operational tolerances and repairability.

Synthesis

Overturning is a macroscopic equilibrium condition that identifies rotation‑dominated instability; preventing it requires evaluating moments together with contact pressures, uplift potential and available passive/anchorage resistance, not moment balance alone.