Ring–truss theory on offshore pipelines buckle propagation

• The ring-truss theory was established to simulate both the axial and circumferential behavior of pipeline during the buckling propagation.
• Full-scale experiments were conducted for comparison.
• A more accurate method was proposed to determine the length of transition zone during the buckling propagation.

Buckle propagation is an essential concern in offshore pipeline design. Once the propagation occurs, it may cause unavoidable failure of an entire pipeline. With the consideration of both longitudinal and hoop deformation behavior of pipeline, a ring-truss theory was analytically established in this study. Laboratory experiments were conducted in full-scale hyperbaric chamber in order to verify the analytical equation. It was observed that the length of transition zone has great influence on determination of propagation pressure. Due to the difficulties of measurement during test process, the length of transition zone was obtained using the finite element simulation. The comparison of propagation pressure between the current study and published model shows that for small diameter to thickness ratio, the ring-truss model is the one that is closest to the actual situation.