Formulation of consistent nonlinear restoring stiffness for dynamic analysis of tension leg platform and its influence on response

Senjanović, Ivo and Tomić, Marko and Hadžić, Neven (2013) Formulation of consistent nonlinear restoring stiffness for dynamic analysis of tension leg platform and its influence on response. = Formulation of consistent nonlinear restoring stiffness for dynamic analysis of tension leg platform and its influence on response. Marine Structures, 30. pp. 1-32. ISSN 0951-8339. Vrsta rada: ["eprint_fieldopt_article_type_article" not defined]. Kvartili JCR: Q1 (2013). Točan broj autora: 3.

Full text not available from this repository.
Official URL: https://doi.org/10.1016/j.marstruc.2012.10.007

Abstract

Shortcomings of the traditionally used nonlinear restoring stiffness of TLPs, i.e. unrealistically high stiffness of horizontal motions, their uncoupling and secant formulation are pointed out. Therefore, new consistent restoring stiffness is derived. The platform is considered as a rigid body moored by flexible pretensioned tendons. Global horizontal low frequency motions (surge, sway and yaw) with large amplitudes as a result of dominant second order wave excitation and small stiffness, and vertical local motions (heave, roll and pitch) of higher frequency and small amplitudes excited by the first order wave forces, are distinguished. Hence, horizontal displacements represent position parameters in analysis of vertical motions. First, the linear restoring stiffness, which consists of the tendon conventional axial stiffness, the tendon geometric stiffness and the platform hydrostatic stiffness, is established. Then it is extended to large displacements resulting in new secant restoring stiffness. It depends on surge, sway and yaw displacements and is the same in any horizontal direction. Also, the tangent stiffness, which gives more accurate results, is derived. Heave is defined as vertical projection of axial tendon vibrations and platform tangential oscillations, which are analyzed in their natural moving coordinate system. Inertia force due to setdown, as a slave d.o.f. of the master horizontal motions, is taken into account in the dynamic equilibrium equations. As a result the complete tangential stiffness matrix of horizontal and vertical motions includes 7 d.o.f. The known secant restoring stiffness matrices are compared with the new one and noticed differences are discussed. All theoretical contributions are illustrated by relatively simple numerical example.

Item Type: Article (["eprint_fieldopt_article_type_article" not defined])
Keywords (Croatian): Coupled motions; Linear stiffness; Non-linear stiffness; Set-down; Springing; Stiffness matrix; Tendons; Tension-leg platforms; Stiffness; accuracy assessment; amplitude; dynamic analysis; dynamic response; hydrostatics; inertia; nonlinearity; stiffness; structural analysis; structural response; tension leg platform; water wave; wave modeling; wave-structure interaction
Subjects: TECHNICAL SCIENCE > Shipbuilding
Divisions: 600 Department of Naval Engineering and Marine Technology > 620 Chair of Marine Structures Design
Indexed in Web of Science: Yes
Indexed in Current Contents: Yes
Quartiles: Q1 (2013)
Date Deposited: 05 May 2015 12:17
Last Modified: 20 Dec 2017 09:16
URI: http://repozitorij.fsb.hr/id/eprint/4088

Actions (login required)

View Item View Item