Ultimate Strength of Columns with Residual Stresses (2 nd Report)

Abstract

The author had studied this problem and reported as the I st Report few years ago. In which, A. “modified Shanley model” was studied and the concept of tangent modulus theory was accepted as a, first approximation.In this report, the author again treated the same problem more thoroughly by planning series of tests and a particular distribution of welding residual stresses i. e. “reversed” -specimens. (Here, “reversed” means that the flange ends of welded columns with I-section have tensile residual stresses, in stead of usual compressive residual stresses.) The new end-fixtures which consist of two tapered circular wedges and driving worm gears, were designed to make the perfect alignment of columns easy.The findings are follows : (a) The “reversed” -specimen (which have reversed distribution of residual stress) may reach at the highest ultimate strength of annealed-specimen, but may not exceed that value by a great amount.(b) The test results of high-tensile steel (Welten-50, YAWATA Iron & Steel Co. Ltd.) columns showed a good agreement with the theoretical calculation as well as in case of mild steel. columns in the 1st report.(c) The tangent modulus load was again verified as a good design standard for welded columns.