That unimpressive little building is a furniture warehouse in Rockaway, constructed in 1909 and badly damaged by fire in 1916. Before the fire there was a wood-frame factory on the right side of the building, where the furniture stored in the warehouse was made; the fire started in the factory and completely destroyed it.
I’ve talked at some length here about the fact that failure is one of the best ways for engineers to learn. The picture above is from a forensic engineering report on that fire, and I’ve discussed that kind of reporting as well. The best source for forensic discussion of ordinary buildings is the Structural Safety website. The simple fact is that we can only learn from failures if we know what happened, so forensic reporting is the critical link in failure-based improvement in engineering.
Here’s what happened in that warehouse:
That’s not a concrete wall filling most of the image: it’s a floor slab from the level above, collapsed and hanging by one edge. Every member in the photo – the column on the left, the two beams supported on the column, the slab – has failed, but only the slab has had catastrophic failure. Had anyone been standing on or below that slab, they would likely have been seriously injured or killed. The column, on the other hand, is in rough shape, but it is still carrying load. It’s going to have to be demolished, but it continued to perform well enough in failure that it’s not even close to being the most frightening thing in this photo.
The building contained a lot of flammable material: the wood furniture obviously, but also paper records storage, varnish, and oil. That said, a “fireproof” building should have performed better than this. The report places the blame for the collapses on a lack of “overlap” in the slab reinforcing, what would today be called a lack of continuity. On a larger scale, the concrete structure may have been fire-resistant, but the interior partitions were flammable, the slab penetrations for plumbing were not fire-stopped, and there was no sprinkler system.
In other words – and this was a relatively new lesson in 1916, and arguably not really understood in 1909 – fire-resistance is a building-wide system, of which using a resistant material like concrete is only a part. What happened between 1909 and 1916? The Triangle fire, in 1911, which showed that structural fireproofing alone was simply inadequate to prevent death and destruction from building fires. The report I’ve taken the photos from was part of the profession-wide effort to codify the Triangle lessons by showing that they were true in many fires, not just that one horrific example.
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