Historic Structural Detail: Customized

by Don Friedman on November 30, 2016


Even at its peak of popularity, cast iron was known to have problems. People used it so extensively 130, 140 years ago because it was the strongest material they had and because they could do so much with it, even with its flaws.

One of the advantages of cast iron is in its name: casting. Any shape required could be cast, giving iron freedom that we associate today with concrete. Because welding wrought iron and steel was not a realistic possibility in the nineteenth century, it was not possible to make similarly complicated shapes out of rolled plates and angles without the use of numerous rivets or bolts.

The picture above shows two steel beams supported on a stiffened-seat bracket that projects from a rectangular-section cast-iron column. Since the beams are different depths (because they span different lengths and therefore needed different moment capacities) the bracket splits to accommodate both. That’s a quite elegant solution compared to, say, the shims that might be used for a similar connection in steel.

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