Worse Than Termites

From a construction site, some steel that’s been nibbled on. The building has the typical NYC structure for the 1920s: a steel frame encased in concrete fireproofing that was place integrally with the floor slabs. In case it’s not clear, that photo was shot looking up, so you’re seeing the underside of the slab above …

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Other People’s Cleverness

I like to look at solutions that other engineers have used on problems similar to the ones I face. Not just engineers: builders and architects often suggest ideas that are worth thinking about. If I don’t like their solutions, I’m no worse off than I was before; if I like them then I can use …

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Mansard Stability

The defining feature of a mansard roof, a sloped facade/roof, is mildly problematic as structure. Under just the gravity load of the wall’s own weight, there is a small overturning moment, which is resisted as an inward thrust at the top and an outward thrust at the base. If the sloped wall is carrying other …

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Why Did They Do That?

A large part of field investigation is trying to get inside the head of whoever designed and built the structure you are looking at.* The idea is that people do things for rational** reasons so if we can figure out those reasons we have a head-start on understanding the built result. The more you understand …

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