A Johnson bar (also Johnson corrugated bar) is a type of corrugated high-carbon steel bar used to reinforce concrete. The Johnson bar was invented by A.L. Johnson of the St. Louis Expanded Metal Company. Its specific efficacy comes from having "alternate elevations and depressions to grip the concrete," with the shoulders of the corrugations having "an inclination with the axis of the bar" to prevent slipping between the bar and the concrete. The pattern of elevations and depressions aids in the stability of the structure; even if a Johnson bar no longer adheres to the concrete (due to vibrations, for instance, or to accidentally being smeared with oil, reducing the adhesion significantly, as may happen during careless construction), it will have a hold on the concrete as strong as or stronger than a "plain" bar (that is, a simple prismatic bar).
Famous quotes containing the words johnson and/or bar:
“Lexicographer: a writer of dictionaries, a harmless drudge, that busies himself in tracing the original, and detailing the signification of words.”
—Samuel Johnson (1709–1784)
“The bar ... is an exercise in solitude. Above all else, it must be quiet, dark, very comfortable—and, contrary to modern mores, no music of any kind, no matter how faint. In sum, there should be no more than a dozen tables, and a clientele that doesn’t like to talk.”
—Luis Buñuel (1900–1983)