Critical Compressive Strain of Linepipes Related to Workhardening Parameters

An approximate solution to predict a critical compressive strain at the peak load (the peak load strain hereinafter) of linepipes subjected to axial compression is proposed in this paper. The approximate solution is derived from the deformation theory applying the stress-strain relationship with non–linear hardening properties, which have not been taken into account in a number of current equations applied for pipeline design. The approximate solution proposed in this paper is a closed form equation, which is useful and effective for the practical application. The parameters in the Ramberg-Osgood representation expressing workhardenability of the linepipes are successfully introduced for the approximate solution. The effectiveness and accuracy of the approximate solution are verified comparing the critical compressive strains of several API 5L grade linepipes obtained by finite element analyses.