Evangelia Koritsa

Graduate Diploma Thesis, July 2013


This work presents a nonlinear finite element simulation of the structural behaviour of ring-stiffened steel tubular members, which are used in offshore applications. In particular, the work focuses on the structural stability analysis (collapse) of those ring-stiffened steel tubes under external pressure. The tubes have a diameter-to-thickness ratio ranging between 30 and 100, and the ring stiffeners are spaced at a distance that vary between 0.5 and 5 tube diameters. Depending on the geometrical characteristics of the tubes and the stiffeners, the stiffened tubes may buckle either in the “local buckling” mode and “global buckling” mode, as shown in Figs. 1 and 2.

The numerical results are compared with available experimental data, conducted by CBI and SwRI research institutes and sponsored by the offshore oil & gas industry. The numerical and experimental results are also compared with analytical predictions from design provisions, regarding the significance of the various parameters which affect pressure capacity.

Spyros A. Karamanos, PhD

Department of Mechanical Engineering | University of Thessaly | Pedion Areos, Volos 38334, Greece
Phone: +30 - 24210 74086, 74360 | Fax : +30 - 24210 74360 | Email: This email address is being protected from spambots. You need JavaScript enabled to view it.

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