Relating Damage To Structural Type

by Don Friedman on November 22, 2017

Some stereoscopic views of Chicago after the 1871 fire:

That’s the kind of devastation that a firestorm can cause. But it’s worth noting that different types of building fail differently. Nearly every building in Chicago before the fire was either of wood-stud construction (private houses and small commercial buildings) or of masonry walls with wood joists (larger commercial buildings and public buildings). The three buildings pictured above had masonry walls or there’d be nothing to show; as it is, we’re looking at wall remnants and nothing else.

This pattern of failure in a fire is specific to masonry-bearing-wall buildings with wood interiors. Even a building with an unfireproofed steel frame, which would fail as completely in a fire, would fail in a different pattern: because such a building would have thinner walls, it would not leave masonry standing.

If you read enough descriptions of old fires, the pattern repeats itself of the interiors burning out and the walls standing for a while and then either collapsing or being torn down for safety. Just as the introduction of new technology changed the way buildings were constructed and therefore changed the way they were perceived during construction, it changed the way buildings fail and how their failures are perceived. The buildings above are obviously a complete loss, and making the masonry walls thicker and stronger would not have prevented their destruction. The introduction of “fireproof” construction, starting shortly after the Chicago fire, meant that the type of failure in the pictures above became less common over time.

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