On location offshore, jack-up structures are subject to environmental loading from wind, waves and current in addition to self-weight. Over the operational period of the jack-up, the environmental loading on a given site may not be unidirectional along the jack-up’s ‘axis of symmetry’ but may act from different directions and/or be non-collinear (i.e. wind acting from a different direction than waves and current), resulting in complex load paths at the spudcan footings. This paper discusses load paths obtained from experiments on a scaled model jack-up for two different horizontal loading directions and illustrate the implications of spudcan load paths for the overall response of a jack-up to failure. Similar tests were performed at two different relative sand densities, allowing the influence of relative density on jack-up behavior to be investigated. Similitude to the prototype was achieved by conducting the experiments in a geotechnical centrifuge at 200g. The paper concludes with numerical predictions of the experimentally measured response, using a macro-element to model the soil-spudcan interaction coupled to a structural finite element program. The footing macro-element has been developed based on plasticity theory and single footing experiments, but its ability to predict the respective load paths of each of the spudcans in a multi-footing system is demonstrated here. The paper further provides the experimentally measured jack-up push-over capacity and numerical predictions in the context of recommendations of current guidelines. This highlights the requirement of nonlinear elasto-plastic modelling of the load-displacement behavior of the jack-up foundations in order to predict the overall response of the system.
- Ocean, Offshore and Arctic Engineering Division
Push-Over Response of a Jack-Up on Sand of Different Relative Densities
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Bienen, B, Cassidy, MJ, & Gaudin, C. "Push-Over Response of a Jack-Up on Sand of Different Relative Densities." Proceedings of the ASME 2009 28th International Conference on Ocean, Offshore and Arctic Engineering. Volume 7: Offshore Geotechnics; Petroleum Technology. Honolulu, Hawaii, USA. May 31–June 5, 2009. pp. 211-219. ASME. https://doi.org/10.1115/OMAE2009-79236
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