Determination of stress characteristics at Connections of Welded Members using Finite Element Method

Abstract

Tubular members are used in various structural members. They have a pleasant effect and good aesthetic values. They can be used in large roof structures, offshore rigs, pressure vessels, etc. The connection between tubular members normally involves cutting one of the members to obtain an exact fit, followed by welding of the two. This intersection becomes a point of high stress concentration, because of the different weld material present as well as the angle of intersection between the different elements. It can be a point of weakness especially in relation to fracture and fatigue. The state of stress here has to be obtained very accurately in order to design the joint accordingly. Finite element analysis provides one such tool. This paper attempts to provide an insight into how to obtain the three dimensional state of stress existing in the welded connection between two tubular members in an offshore structure. It is shown that results from finite element submodelling analysis are in good agreement with those from conventional parametric equations for the determination of stress concentration factor in tubular joints.