Offshore Structures

Clauss, Günther F.; Lehmann, Eike; Östergaard, Carsten

doi:10.1007/978-1-4471-3193-9

Cited by 49 publications

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“…The formulae for hydrodynamic forces on other columns and pontoons are similar. Using modified Morison equation [9] , force vector per unit length of arbitrary oriented cylinder f n is written as…”

Section: Hydrodynamic Forces Vectorsmentioning

confidence: 99%

Governing equations and numerical solutions of tension leg platform with finite amplitude motion

Zeng

Shen

2007

Appl Math Mech

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It is demonstrated that when tension leg platform (TLP) moves with finite amplitude in waves, the inertia force, the drag force and the buoyancy acting on the platform are nonlinear functions of the response of TLP. The tensions of the tethers are also nonlinear functions of the displacement of TLP. Then the displacement, the velocity and the acceleration of TLP should be taken into account when loads are calculated. In addition, equations of motions should be set up on the instantaneous position. A theoretical model for analyzing the nonlinear behavior of a TLP with finite displacement is developed, in which multifold nonlinearities are taken into account, i.e., finite displacement, coupling of the six degrees of freedom, instantaneous position, instantaneous wet surface, free surface effects and viscous drag force. Based on the theoretical model, the comprehensive nonlinear differential equations are deduced. Then the nonlinear dynamic analysis of ISSC TLP in regular waves is performed in the time domain. The degenerative linear solution of the proposed nonlinear model is verified with existing published one. Furthermore, numerical results are presented, which illustrate that nonlinearities exert a significant influence on the dynamic responses of the TLP.

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Section: Hydrodynamic Forces Vectorsmentioning

confidence: 99%

Governing equations and numerical solutions of tension leg platform with finite amplitude motion

Zeng

Shen

2007

Appl Math Mech

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“…For instance the sea elevation, water partide velocity and acceleration processes generally are assumed stationary Gaussian with zero-mean during sea states of several hours duration and wave-current usually is neglected. For a discussion of these problems see [1].…”

Section: Introductionmentioning

confidence: 99%

“…Under the aforementioned assumptions, the equation of motion is (1) where J.J denotes absolute value; Kn == ~pDCn, KM == ~1rpD 2 CM and KA == ~7rpD 2 (CM-1); Cn and CM are the drag and the inertia coefficients; p is the water density; D is the member diameter; m, c and k are structural parameters; x and y denote the water partide velocity and the structural displacement.…”

Section: Introductionmentioning

confidence: 99%

“…1f the approximation due to Winterstein [2] is used, only the first four order moments of these processes need to be known. For equation (1 ), however, the estimation of even low order moments of y is not straightforward. The statistica!…”

Section: Introductionmentioning

confidence: 99%

“…when large structures and numerous load cases ( sea states) ha ve to be considered. Then the nonlinear term (x-iJ) 1 x-iJ 1 is simply replaced by a linear term Aa-x-y(x-i;), where A is a constant and O" x-y denotes the standard deviation of ( x -iJ) as proposcd already by Borgman [3].…”

Section: Introductionmentioning

confidence: 99%

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Approximation of non-normal responses for drag dominated offshore structures

Bouyssy

Rackwitz

1995

Reliability and Optimization of Structural Systems

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For deep water offshore structures, the modeling of random waves loads by the Morison equation yields an equation of motion which admits no analytical solution except in few limit cases. This also holds for response moments which have a great influence on the results of reliability analyses. If polynomial approximations of the Morison drag loads are introduced, some procedures are available to obtain the stationary moments of the approximate response. These procedures result in large computer codes and time consuming computations if large structures are considered. Therefore, only first order approximations of the drag nonlinearity usually can be handled. In the paper, the ability of two famous linearization schemes to predict response variance and response fourth moment is numerically investigated. Improvements of these schemes are considered. For quasi-static structures, it is shown that except in very simple cases it is practically impossible to optimize linearization schemes to fit response variance or fourth moment.

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Types of Bottom‐Founded Structures

Humphrey¹

2018

Encyclopedia of Maritime and Offshore Engineering

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This article presents a brief historical overview of facilities development for the oil and gas industry. The key milestone projects as well as the changes in structural concepts as the industry expanded to deeper water depths are discussed. The types of foundations and anchorage systems used to support and moor these facilities are also discussed. The evolution for structures and foundations demonstrates the creativity and high level technology required to develop increasingly more difficulty to access offshore hydrocarbons.

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Offshore Structures

Cited by 49 publications

References 0 publications

Governing equations and numerical solutions of tension leg platform with finite amplitude motion

Governing equations and numerical solutions of tension leg platform with finite amplitude motion

Approximation of non-normal responses for drag dominated offshore structures

Types of Bottom‐Founded Structures

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