Extreme response statistics for drag dominated offshore structures

The paper presents a study of extreme response statistics of drag dominated offshore structures, subjected to severe sea states. The nature of the hydrodynamic forces acting on the structure is highly nonlinear under such conditions. Additionally to drag forces, the so-called inundation effect must also be taken into account. In the present paper a stochastic force model is introduced that captures both these phenomena in a fairly simple manner allowing for efficient calculation of the extreme response statistics. In fact, the proposed model opens up the possibility to calculate efficiently even long-term extreme response statistics, which is an important issue for the design of offshore structures. Comparison with the results of Monte Carlo simulations for a jacket structure indicates that good accuracy can be obtained for the extreme response predictions.

[1]  Subrata K. Chakrabarti,et al.  Handbook of Offshore Engineering , 2005 .

[2]  Xiang Yuan Zheng,et al.  Polynomial Approximations of Wave Loading and Superharmonic Responses of Fixed Structures , 2003 .

[3]  Achintya Haldar,et al.  Uncertainty modeling in vibration, control and fuzzy analysis of structural systems , 1997 .

[4]  T. Sarpkaya,et al.  Mechanics of wave forces on offshore structures , 1981 .

[5]  S. Orszag,et al.  Advanced Mathematical Methods For Scientists And Engineers , 1979 .

[6]  Hans Christian Karlsen,et al.  Numerical calculation of the level crossing rate of second order stochastic Volterra systems , 2004 .

[7]  S. Winterstein.  Nonlinear Vibration Models for Extremes and Fatigue , 1988 .

[8]  A. Naess,et al.  An Efficient Numerical Method for Calculating the Statistical Distribution of Combined First-Order and Wave-Drift Response , 1992 .

[9]  Arvid Naess,et al.  Frequency domain analysis of dynamic response of drag dominated offshore structures , 1997 .

[10]  Arvid Naess,et al.  Technical note: On the long-term statistics of extremes , 1984 .

[11]  James Franklin Wilson,et al.  Dynamics of Offshore Structures , 1984 .

[12]  Xiang Yuan Zheng,et al.  Response Spectrum Estimation for Fixed Offshore Structures With Inundation Effect Included: A Price’s Theorem Approach , 2004 .

[13]  Ahsan Kareem,et al.  DYNAMICS OF NONLINEAR STOCHASTIC SYSTEMS: A FREQUENCY DOMAIN APPROACH , 1997 .

[14]  Arvid Naess,et al.  Efficient estimation of extreme response of drag-dominated offshore structures by Monte Carlo simulation , 2007 .