Experimental study of non-linear loads on vertical cylinders in steep random waves
- Norwegian Marine Technology Research Inst. A/S, Trondheim (Norway)
A description of laboratory experiments carried out with fixed, vertical truncated cylinders in irregular waves is given. With a model scale about 1:50, the tested models correspond approximately to North Sea large-volume platform dimensions. Tests with a single cylinder as well as with an array of cylinders are performed. Global horizontal forces and pitch moments on individual cylinders were measured. In the present report, analysis of surge force measurements are presented and discussed. The background of the study is the need for research on the hydrodynamic excitation of ringing phenomena. Thus one has emphasized the study of non-linear high-frequency (HF) force contributions generated by steep random waves. It is observed that although they are negligible in the frequency domain, the magnitude of such force components may be up to 10--20% of the total extreme forces, for this particular cylinder. Tests with the multi-column model show that diffraction effects can be important for the magnitude of the HF excitation, but not for the occurrence and nature of such events in itself. Force measurements on the different individual columns show that the HF force signal due to a particular steep wave passing through the structure, is recognized on all the columns, but shape of the signal changes in space.
- OSTI ID:
- 256920
- Report Number(s):
- CONF-950604-; ISBN 1-880653-17-6; TRN: IM9631%%126
- Resource Relation:
- Conference: 5. international conference on offshore and polar engineering, The Hague (Netherlands), 11-15 Jun 1995; Other Information: PBD: 1995; Related Information: Is Part Of Proceedings of the fifth (1995) international offshore and polar engineering conference. Volume 1; Chung, J.S. [ed.] [Colorado School of Mines, Golden, CO (United States)]; Das, B.M. [ed.] [California State Univ., Sacramento, CA (United States)]; Natvig, B.J. [ed.] [Norwegian Contractors, Stabekk (Norway)]; Olagnon, M. [ed.] [IFREMER, Plouzanne (France)]; PB: 646 p.
- Country of Publication:
- United States
- Language:
- English
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