Dangerous damage of RC structural members caused by thermal spalling of concrete during fire in an enclosed car park of residential building

This paper presents a description of structural damage caused by a fire in an underground car park of a six-storey residential building. It also describes how the damaged members were repaired. It was found that the fire had reached the fully developed stage over a large area of the car park, which resulted in considerable extent of damage: (1) approximately 210 m 2 of the ceiling slab were completely destroyed - it was necessary to demolish the slab and replace it with a new one, (2) one of the walls constituting the main load-bearing structure of the building was in a state very close to actual destruction, (3) several columns required significant strengthening. The main cause of the resulting damage was the unusually intense thermal spalling of the concrete. • The paper describes the damage, safety assessment, and structural repair following a fire in an underground car park. • The extent of the fire damage was very significant. • Members of the main load-bearing structure needed significant strengthening. • A portion of the car park concrete ceiling slab (approx. 210 m 2 ) had to be demolished and replaced with a new slab. • The cause of the significant damage to the structure was the unusually intense thermal spalling of the concrete.