Disproportionate Collapse
Definition
Collapse extent that is far greater than would be expected from the triggering event. Ronan Point is the canonical example: a small gas explosion caused a corner bay to collapse from roof to ground.
- Canonical case
- Ronan Point, London, 1968
- Trigger in that case
- Small gas explosion
- Extent
- Corner bay collapsed roof to ground
- Field
- Structural forensic engineering
Common questions
What design flaw makes a structure prone to disproportionate collapse?+
A lack of redundant load paths is the usual cause: precast panel buildings like Ronan Point relied on individual panels for both gravity and lateral support, so removing one panel left nothing to carry the load above it.
How do codes address disproportionate collapse today?+
Modern building codes require tie forces or alternate load-path checks so that the loss of any single structural element is contained locally rather than propagating through the whole structure, a direct regulatory response to cases like Ronan Point.
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