Numerical prediction of the structural behavior of welded buried reduced-tee pipelines under complex loading

Under various loading conditions and due to their geometric shape, tabular structures made of X60 or other steels differ in their stresses. These welded structures are permanently pressurized to levels that accumulate and cause damage during service. By means of the finite element method and using the Abaqus numerical calculation code, this work consists in analyzing the response of the entire structure, a large part of which is buried, consisting of a tee-pipe and an elbow which are welded by straight tubular lengths. The pressurized tubular structure is stressed under complex loads that are a combination of bending moment and unidirectional load. Using a finite element model that takes account of the tubular-soil interface, the structure is analyzed in these standardized dimensions under real conditions and in a pitting design where the various loading modes combined present a probable mode of loading. The elastic-plastic behavior of the tubular elements and the welded joint is investigated using the Voce model and Von Mises’ equivalent stress flow theory, while the damage to the structure through crack initiation and propagation is ensured using the XFEM technique, taking into account the soil-pipe interaction, the present analysis determines the mechanical response of the entire tubular structure to various complex loads, which can, in terms of their flexibility, contribute to the reduction of deformations induced by the soil and/or those coming from the ventilated part of the pipe.