Damage investigation in steel pipe under pressure and combined bending moment: Application in structure connected by elbow and reduced tee

Steel tubular structures in pipelines, or those connections such as concentric reductions, reduced tees, and elbows, all differ in their response to loading, they are sometimes solicited to complex and combined loads, which accumulate with the internal pressure to their solicitation cause in certain situation their damage, the objective in this analysis is to numerically predict the mechanical behavior until damage of a complete tubular structure, which contains the connecting elements of an elbow and a reduced tee attached to each other by straight tubular parts, this structure, by its standardized dimensions presents a real design of a main pipeline spigot for a possible supply line, this tubular structure is analyzed in this work under these real pressure conditions, and combined loads probably coming from the weight of a valve, or a pipe flanged to this spigot element or other, in X60 steel This structure is solicited under different combined modes of loading. The elastic-plastic behavior is under Voce's model and Von Mises' equivalent stress flow theory, the damage of the structure by crack initiation and propagation is ensured by using the XFEM technique, the response up to damage of the structure is evaluated under the effect of the parameters of the combined loading mode, we present by angular bendingrotation moment curves that these parameters clearly condition the response and the level of damage.