Wrought Iron

156 Years Of Dirt

by Don Friedman on March 16, 2017

Whatever that light-gray dust is – some combination of rotted wood, ancient coal smoke, and pigeon crap, most likely – it was damned difficult to wash off my hands and shirt. But that’s not the point.

What is this thing? It’s the cast-iron arch holding up the rear wall of an 1861 loft building over the rear extension of the first floor. If I could have got a better angle, which was not possible while perched on a ladder, the wrought-iron tie rod would be visible just below the wadded-up paper.

It can be hard to visualize this. Here’s an example from another building, exposed during construction:

In this case, there are two arches: the one we’re looking at and its twin off to the left, and the wrought-iron tie rods (in this case, there are two, front and back, and they’re square in cross-section) are continuous from the brick pier on the right, past the round cast-iron column between the arches (on the left of the photo) and off to the left brick pier out of the frame.

Don’t let anybody tell you that masonry walls were first carried on metal with the invention of the steel skeleton frame in the 1890s. People in the 1860s knew how to do it just fine. They couldn’t build a whole building that way, but then again it would not have occurred to them to try.

A Subtle Hint

January 24, 2017

That picture was taken in a mid-to-late-nineteenth-century industrial building, on the top floor with only the attic above. The exposed wood beam is about 8 inches wide and 12 inches deep but appears to span some fifty feet, which is obviously ridiculous. The building has a gable roof so the most likely bet is that […]

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June 30, 2016

Know any blacksmiths? There’s a job opening right now with the New York City Department of Parks and Recreation. This might sound like a joke* but it’s serious. Blacksmiths shape iron and steel in complex three-dimensional configurations that are not easily achievable using other methods. The introduction of CAD/CAM cutters allows for extremely complex and […]

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Historic Structural Detail: Geometric Strength

May 26, 2016

Some structural forms are more efficient than others. For example, roof trusses tend to be deep (vertically) relative to their spans. Trusses can be examined at two scales: at a small scale, member by member and connection by connection, or at the overall scale, where they are analogues of beams. It’s at the overall scale […]

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Historic Structural Detail: A Composite Arch

March 16, 2016

One of the earliest challenges for structural engineers – long before the profession formally existed – was how to support masonry walls over openings. The tight column spacing of Greek and Egyptian temples, for example, was based in part on the limited spanning capacity of stone beams. Masonry arches, as used by the Romans, could span […]

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