Ransome bar.
Corrugated steel bar. St. Louis Expanded Metal Fire Proofing Co.
Thacher bar.
Disposal of Steel in Reinforced Concrete.
Reinforced concrete has been thoroughly studied with regard to its properties and the forms in which it may be best disposed. Since the strength of concrete is usually ten-fold greater in compression than in tension, designs should be compressive whenever possible, all tensile strains being carefully committed to the steel. In arched bridges the strains are chiefly compressive, hence the success with which they are executed in reinforced concrete. Mr. Edwin Thacher of New York, eminent in this branch of engineering, sees no reason why spans of 500 feet should not be feasible and safe. Some remarkable discoveries have followed upon experiments with reinforcement diverse in form and variously placed within a mass. To increase the strength of a square steel bar Mr. E. L. Ransome twists it into spiral form; on square steel bars Mr. A. L. Johnson places projections; Mr. Edwin Thacher rolls his steel into sections alternately flat and round. All these contours have large surfaces at which metal and concrete adhere. Reinforcing bars designed by Mr. Julius Kahn and by the Hennibique Construction Company are smooth, and slightly bent from straightness at intervals. In every case the question is, Where will the tensile strength of the steel do most good, because most needed? M. Considere has found that concrete hooped with steel wire has more than twice the resistance of concrete in which an equal amount of steel is centrally placed. In his floor constructions M. Matrai gives steel wires the curves they would take under a load. Keeping to its original lines the Monier reinforcement of to-day consists in a rectangular netting of rods or wires. Somewhat similar is the expanded metal backing invented by Mr. J. F. Golding; it is sheet steel pierced with parallel rows of slits which are expanded until the metal assumes the form shown in an accompanying illustration. A lock woven-wire fabric of galvanized steel wire is made by W. N. Wight & Company, New York, in any desired size of mesh, with an ultimate strength of 116,000 pounds per square inch of metal.
Kahn bar.
