殘留応力を有する柱の塑性域における挫屈について(第2報)

概要

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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 & SteelCo. Ltd.) columns showed a good agreement with the theoretical calculation as well as in case of mild steel columns in the 1 st report.(c) The tangent modulus load was again verified as a good design standard for welded columns.