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:
“There is no private house in which people can enjoy themselves so well as at a capital tavern.... No, Sir; there is nothing which has yet been contrived by man by which so much happiness is produced as by a good tavern or inn.”
—Samuel Johnson (1709–1784)
“Hemingway is terribly limited. His technique is good for short stories, for people who meet once in a bar very late at night, but do not enter into relations. But not for the novel.”
—W.H. (Wystan Hugh)