Katrantzos Sport, Athens — the Roof Slab Expanded, Pushed the Columns, Floors Fell

The Katrantzos Sport department store, an eight-storey reinforced-concrete building in central Athens, partially collapsed in the early hours of 19 December 1980, when an after-hours arson fire drove the unprotected concrete roof slab to expand, push out the perimeter columns, and drop a major part of the upper floors; the building was empty, so the death toll was zero. The fire did not burn the building down. It heated the concrete until the structure tried to expand, and because the frame had no room to expand into, the expansion turned into force — force that pushed the perimeter columns outward until the floors they carried fell.

This is one of the cleanest documented cases of fire-induced collapse by restrained thermal expansion in a concrete frame. The fire, set around 03:07 with a simultaneous attack on the nearby Minion store, began on the seventh floor and ran the full height of the building unchecked: there was no automatic sprinkler system and effectively no vertical or horizontal compartmentation to slow it. Over a burn of two to three hours, fire temperatures reached roughly 1,000 degrees Celsius. The 18-centimetre conventional concrete roof slab, supported on 41-centimetre square reinforced tied columns, expanded horizontally as it heated — and with no expansion joints in the floors or the roof to absorb that movement, the slab simply shoved its own supports aside. One corner of the roof displaced laterally by almost 60 centimetres.

That displacement was the failure. The columns and connections at the top of the building were overloaded not by the weight they were designed to carry but by the differential thermal expansion the structure could not relieve, and a major part of the fifth through eighth floors came down. The lower floors and the building’s overall stability survived, which is why the case is catalogued as a partial collapse rather than a total one.

The arson was never solved; the case eventually reached the statute of limitations and was legally closed. But the structural verdict was unambiguous and is the reason the building appears in the engineering literature, including NIST’s survey of fire-induced building collapses. Katrantzos is the textbook demonstration that a reinforced-concrete frame can be defeated by fire without burning, if its thermal expansion is restrained and it has nowhere to grow.

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