Historic Structural Detail: Elegant Steel

by Don Friedman on January 6, 2016

I was on site yesterday, reviewing the conditions exposed in an 1890s building after the interior-finish demolition complete. At an upper floor, there was an opening about eight feet wide in an interior brick bearing wall; rather than have a steel lintel that spanned the full distance, there was a steel lintel supported in the middle by a slender column. (Click to enlarge the picture.)

IMG_1220

The column cross-section consists of four angles placed back-to-back, with the occasional tie plate riveting the four angles together. The page below, from Steel Construction by Edward Tucker, consists of various column sections in use in 1908. Figure 5 shows two-angle and 4-angle columns, with the angles shown as black and the rivet heads at the tie plates seen as black-outlined white half-circles.

Steel_Construction (dragged)

The two- and four-angle columns in figure 5 are not particularly good. Columns need stiffness against lateral buckling, and that is achieved by having as much material as far away from the center of the section as is possible. The box column in figure 15 or the z-bar columns in figure 23 are far stiffer.

But the four-angle column, as seen in yesterday’s photo, is quite spiffy.

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