Now that a two-by-four is only 1 1/2 by 3 1/2 inches instead of 1 5/8 by 3 5/8 is it necessary to compensate in figuring loads on shores?
Yes. A complete set of tables for use as a guide to shoring calculations with all the new 1970 lumber sizes up to six-by-sixes has been published in the ACI Journal, May 1973, pages 362 to 367. (A single copy of the ACI Journal can be purchased for $2 from the American Concrete Institute, P. O. Box 4754 Redford Station, Detroit, Michigan 48219, and annual subscriptions for nonmembers are $22.) Data are given for safe shore loads for stress values representative of most eastern spruce, southern pine and Douglas fir-larch. The tables are meant to be used for guidance only and not for lumber with lower stress ratings or no ratings at all. It is recommended that henceforth all calculations be based on new lumber sizes, since it is virtually impossible to keep new and old sizes separated on the job.