Influence of structural distortion and bend angle on the collapse load of non-pressurized pipe bends under in-plane closing and opening moments

Abstract

This research quantifies the implications of structural distortions and bend angle on the collapse load of non-pressurized different bend angle pipe bends. The analysis was carried out for two loading cases namely pipe bends subjected to in-plane closing bending (IPCB) and in-plane opening bending (IPOB). The method used was a three-dimensional (3D) non-linear finite element analysis with a large strain formulation. The chosen material was considered to be Elastic-perfectly plastic (EPP). Bend angle was varied from 30° to 90° with an increment of 30° while structural distortion (ovality) was varied from 0 to 15% at a span of 5%. The twice elastic slope (TES) method was adopted to determine the collapse load of all the considered pipe bend models from their rotation-moment curves. The results show that ovality impact decreased with an increase in the bend angle. When comparing pipe bends with smaller bend radii and smaller bend angles with those having larger bend radii, massive ovality impact was observed. This effect was found to be greater in IPCB compared to IPOB.