An Analytical Method on Residual Stresses in Welded Built-Up Shell Structures

Abstract

Most steel shell structures are built up with welding. The residual stresses and deformations due to welds have bad effects on the static and fatigue strength of shell structures. And the residual stresses often cause stress corrosion. Accordingly, many researches are brought out; on circumferential welds of pipes, straight seam welded pipes and so on. However, each of these researches separatly treats a shell in particular, and there have been little studies on residual stresses due to the weld of general shells.This paper deals with the analytical method on residual stresses in welded built-up shell structures. The method is based on 1) the concept of 'inherent stress' due to weld shrinkage, 2) the extension of Duhamel's analogy, and 3) the geometrical characteristics of curved weld beads. Using the method the welding residual stresses in general-shaped shell structures are able to be calculated. The analytical results of the residual stresses in welded built-up shell structures-circumferential welds of pipes, circumferential welds of spherical shells and straight seam welded pipes-are shown. The results are compared with published experimental results. The analytical results show good agreement with the experimental results. The final part of this paper deals with the formula and the estimating procedure of 'inherent stress'; that depends upon the welding parameters, the geometrical characteristics of weld beads and the material property (yield stress).