This paper presents a finite element analysis to quantify the effects of weld-induced residual stress and deformation on the compression behavior of girth-welded steel pipes. Finite element modeling of the weld-induced imperfections is first described. Nonlinear finite element analysis in which the behavior of girth-welded steel pipes in compression was explored incorporating the effects of the weldinduced residual stress and deformation is next discussed. Results showed that the weld-induced imperfections significantly affect the behavior of girth-welded steel pipes under axial compression.
The cylindrical shells, especially in the steel pipe form, are widely used in a range of engineering applications such as offshore pipelines, pressurized underground pipelines and steel pipe piles. During their service life, these structures are subject to loading of various types. In the realistic applications, owing to the relatively long geometry compared to the diameter and thickness, joining of the pipes is frequently required. The girth welds is a common type of joint in pipe systems. When two pipes are welded together, undesired residual stress and deformation are produced in the vicinity of the welds. This is due to the highly localized, non-uniform, transient heating and subsequent cooling of the welded material, and the non-linearity of material properties. Weld-induced residual stresses may lead to cracking just after welding and sometimes later, during the intended service life. Particularly, tensile residual stresses near the welds generally have adverse effects, causing stress raising, fatigue failure, and brittle fracture (Taljat et al., 1998). Moreover, when combined with service loads, these stresses cause premature yielding and loss of stiffness and may lead to deterioration of load carrying capacity. Welding deformation, i.e. weld depression induced by circumferential shrinkage of the welds has also been founded to have significant effects on the compression behavior of welded pipes (Edlund, 2007).
