A Bit Bloated

by Don Friedman on November 7, 2016

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That picture was taken during interior-finish demolition in the penthouse of an old skeleton-frame building. Like many buildings of this type, the only setbacks are at the penthouse level, so the penthouse columns are only one-story high and are quite small.

In this case, the column section consists of two angles kitty-corner to one another. In other words, the back outside corners of the two angles face each other so that the four legs point out north, south, east, and west. It’s a terrible column section for bending, but better than a single for axial compression. It’s good enough for a one-story penthouse, sitting on the main structure of the building.

The column has to be fireproofed, and it’s generally true that the smaller a steel section is the more fireproofing  it will require. (Bigger sections act better as heat sinks to carry heat away from the source.) But this 6-inch wide column did not need a 20-inch-wide gypsum-board enclosure. One of the beauties of steel construction is the slenderness of the steel elements compared to other materials, and showing that away behind a mountain of gypsum board seems wrong.

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