An enhanced pipe elbow element - application in plastic limit analysis of pipe structures

In this paper, we present a new pipe elbow element based on a previous simpli"ed model proposed by Bathe and Almeida [1, 2] and modi"ed by Militello and Huespe [3]. It is really a beam-type element but it describes the ovalization, warping, radial expansion and non-symmetric deformation of cross-section of curved pipe with Fourier series. Therefore, it could model precisely enough a real pipe elbow structure but remains simple. The extensive loading cases are e!ectively implemented by the proposed numerical techniques and displacement model. The developed element is used in this paper in plastic limit analysis of pipe elbow structures. This is realized by means of a direct mathematical programming technique. Various elastic and plastic limit state analyses of straight pipes and elbow structures are presented, which illustrates the e$ciency of the element and the numerical method. Copyright ( 1999 John Wiley & Sons, Ltd