In an earlier paper on "The Effect of Lateral Reinforcement in Reinforced Concrete Columns,” published in the July issue of THE STRUCTURAL ENGINEER, the results of a series of tests on small columns with varying reinforcement were analysed, and a formula evolved which fitted the observed values of ultimate load on the columns within 4 per cent. The columns from which the formula was derived were a standard size, 11.7 in. long X 3.5 in. square, having longitudinal bars, four in number, arranged as a square of overall dimensions 2.5 in. X 2.5 in., and binders of the same internal dimension. Working with a concrete giving a cube strength on 4 in. cubes at 28 days of about 4,000 Ibs. per sq. in., and a range of longitudinal steel from 1/2 in. bars to zero, with binders of pitches from 3/4 in. to 11 1/2 in. of 14 to 4 gauge bright drawn wire, the formula evolved was:
Ultimate Load = A.w + B.x + C.y + D.z
Jeffrey William Hitchen King