Offshore Technology Research Center


OTRC Project Summary

Project Title:

Stability of Deep-Water Pipelines Under Combined Loading

Prinicipal Investigators:

John Tassoulas


National Science Foundation

Completion Date:

June, 1991

Final Report ID#

B18(Click to view final report abstract)

This study is aimed at the development of a rigorous finite-element technique for the analysis of tubular structures.  Another objective is the investigation of pipeline behavior under an arbitrary loading sequence, since very limited results exist for paths other than the k→p, p→k paths.  Results are obtained for the case of the so-called radial path in which pressure and curvature are increased simultaneously and in some proportion, until buckling occurs.  A simple collapse criterion, appropriate for all paths, is proposed and the radical, k→p, p→k paths are examined.  In order to simulate the typical experimental procedure, a technique has been developed  and is described below for  three-dimensional analysis of tubular structures.  A simpler version for two-dimensional analysis which assumes constant curvature along the tube is also presented.  Its main advantage over the three-dimensional formulation is the low computational cost.  Finally, an investigation of the effects of tension loading on the response of pipelines under external pressure and bending is presented.  In all cases, results are reported in the form of interaction diagrams and are of particular significance for safe pipeline design.

Related Publications: Karamanos, S.A. and Tassoulas, J.L., "Stability of Deep-Water Pipelines Under Combined Loading," Paper No. 6759, Proceedings, Offshore Technology Conference, Houston, Texas, May 6-9, 1991.

Karamanos, S.A. and Tassoulas, J.L., "Pipeline Stability in Deep Water," Proceedings, First National Conference on Steel Structures, Athens, Greece, June 6-7, 1991.

Karamanos, S.A. and Tassoulas, J.L. “Stability of Inelastic Tubes Under External Pressure and Bending,” Journal of Engineering Mechanics, ASCE, Vol. 117, No. 12, pp.2845-2861, December 1991.

Karamanos, S.A. and Tassoulas, J.L., "Stability of Inelastic Tubes Under Combined Tension and Bending," Proceedings, Tenth Structures Congress, ASCE, San Antonio, Texas, April 13-15, 1992.


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