Residual Stresses in Welded Tubular T-joints

Abstract

Many off-shore structures of fixed or mobile platforms, are mainly composed of tubes of various diameters. The structures have many tubular joints called nodes, where two tubes or more connected together with welding in the same space. Due to the weld, there are residual stresses in tubular joints. It is said that the residual stresses have bad effects on static and fatigue strength of the joints. However, few investigations have been carried out for the problem of residual stresses in welded tubular joints. So, it has been almost imposible to take residual stresses into consideration when designing the joints.This paper deals with the residual stresses in welded tubular T-joint, that is the most simple and popular type of the tubular joints. Experimental and analytical results are shown. Residual stresses of two specimens are measured. One specimen has 700 mm diameter chord and 400 mm diameter brace, another has 700 mm diameter chord and 300 mm diameter brace. FEM with shell elements is used for the full model analysis. Then, plane strain elements are used to perform the analysis of weld toes. Both experimental and analytical results are thoroughtly agreed for the most part.