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:
“But, most of all, the Great Society is not a safe harbor, a resting place, a final objective, a finished work. It is a challenge constantly renewed, beckoning us toward a destiny where the meaning of our lives matches the marvelous products of our labor.”
—Lyndon Baines Johnson (1908–1973)
“The bar is the male kingdom. For centuries it was the bastion of male privilege, the gathering place for men away from their women, a place where men could go to freely indulge in The Bull Session ... the release of the guilty anxiety of the oppressor class.”
—Shulamith Firestone (b. 1945)