Damping of jacket structures are discussed on the basis of full-scale measurements. During a submarine impact with a jacket structure, unique transient response time series, damping properties are evaluated in terms of the nature and magnitude of the total damping. It is shown that the damping is highly nonlinear and fits a Coulomb-type model reasonably well. The damping magnitude expressed as the relative damping ratio is estimated to be in the range from 0.5 to 3.0 percent, dependent on the motion amplitude. Within the range of motion amplitudes experienced during the impact, the damping decreases with increasing motion amplitudes. The resonant motion amplitudes recorded during the impact are shown to be far greater than the expected dynamic motion amplitudes during a storm period.

1.
Brouwers, J. J. M., 1982, “Response Near Resonance of Nonlinearly Damped Systems Subjected to Random Excitation With Application to Marine Risers,” Ocean Engineering.
2.
Nayfeh, A. H., and Mook, D. T., 1979, Nonlinear Oscillations, John Wiley and Sons, New York, NY.
3.
Newman, J. N., 1977, Marine Hydrodynamics, MIT Press, Cambridge, MA.
4.
Spidso̸e, N., and Langen, I., 1985, “Damping of Fixed Offshore Platforms,” Behavior of Offshore Structures, Elsevier Science Publishers B. V., Amsterdam, The Netherlands.
5.
Thuestad, T. C., and Nielsen, F. G., 1990, “Submarine Impact with the Oseberg Jacket,” Proceedings of Ninth International Conference of Offshore Mechanics and Arctic Engineering, Houston, TX.
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