Effect of wave inhomogeneity on fatigue damage of mooring lines of a side-anchored floating bridge

2016 ◽

Author(s):

Sverre Wiborg ◽

Tina Vejrum ◽

Erik Sundet ◽

Per Norum Larsen ◽

Bernt Sørby ◽

...

Keyword(s):

Mooring Lines ◽

Curved Bridge ◽

Floating Bridge ◽

Bridge Crossing

The purpose of this paper is to investigate the main challenges and corresponding solutions for a floating bridge crossing Bjørnafjorden. The paper investigates challenges related to quantification of loads, design of permanent structures as well as temporary phases. The paper evaluates a curved bridge without mooring lines, but considerations are partly valid for a straight bridge anchored to the seabed as well. Both solutions have been used, but the length of the Bjørnafjorden crossing is significantly larger than previous bridges and thus more challenging.

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Mooring System Design and Optimization for Floating Bridge of Urmia Lake

21st International Conference on Offshore Mechanics and Arctic Engineering, Volume 1 ◽

10.1115/omae2002-28343 ◽

2002 ◽

Cited By ~ 1

Author(s):

M. Daghigh ◽

R. T. Paein Koulaei ◽

M. S. Seif

Keyword(s):

Burial Depth ◽

Floating Bodies ◽

Mooring Lines ◽

Sea Floor ◽

Design And Optimization ◽

Sea Bed ◽

Floating Bridge ◽

The Mean

In order to get better understanding on the response of floating bodies, different design aspects of mooring lines has been investigated in this paper. Mooring lines are categerized into two types; the catenary settling on the sea floor (type 1) and the limited one which has no dead-length on sea floor (type 2). It has been observed that the stiffness of both types may be well predicted by Jain’s formulation and in the design process of floating bodies the mooring lines may be replaced by uncoupled horizontal and vertical springs. On the other hand, the anchor capacity against sliding and release from the mean still water has been studied in this paper. From the results of a parametric study, using the discrete element method, the block anchor the dimensions for the Urmia floating bridge has been optimized and the behavior of anchor and seabed deposits for release of block anchor indicates that the burial depth and the stress level on the block anchor itself and the sea bed are in the allowable and elastic region, respectively.

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Fatigue damage induced by nonGaussian bimodal wave loading in mooring lines

Applied Ocean Research ◽

10.1016/j.apor.2007.06.001 ◽

2007 ◽

Vol 29 (1-2) ◽

pp. 45-54 ◽

Cited By ~ 37

Author(s):

Zhen Gao ◽

Torgeir Moan

Keyword(s):

Fatigue Damage ◽

Wave Loading ◽

Mooring Lines

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Fatigue Damage Estimation for Mooring lines of Spar Platform Using System Identification Method

Journal of Ocean Engineering and Technology ◽

10.5574/ksoe.2016.30.3.161 ◽

2016 ◽

Vol 30 (3) ◽

pp. 161-168

Author(s):

Yong-Gyun Kim ◽

Yooil Kim ◽

Byoung-Hoon Kim

Keyword(s):

System Identification ◽

Fatigue Damage ◽

Damage Estimation ◽

Spar Platform ◽

Mooring Lines ◽

System Identification Method ◽

Identification Method

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Effects of Mooring Line Design Parameters on the Line Dynamics and Fatigue Response of Subsea Mooring Lines

Volume 1: Offshore Technology ◽

10.1115/omae2018-78716 ◽

2018 ◽

Author(s):

Hamid Sedghi ◽

Mehrdad Kimiaei

Keyword(s):

Dynamic Analysis ◽

Fatigue Damage ◽

Dynamic Responses ◽

Statistical Characteristics ◽

Design Parameters ◽

Mooring Line ◽

Engineering Practice ◽

Mooring Lines ◽

Fatigue Design ◽

Line Design

Dynamic characteristics of mooring lines play an important role in overall structural response and fatigue design of mooring systems. Full dynamic analysis including line dynamics is a vital part of fatigue design process although in time domain it needs excessive computational efforts. For fatigue analysis of mooring lines where hundreds of different environmental loads have to be checked, alternative analysis approach such as quasi-dynamic analysis with implicit inclusion of the line dynamic effects are used widely in engineering practice. This paper presents the results of series of case studies on the effects of various mooring line design parameters on the line dynamics as well as the mooring line dynamic fatigue response. Various mooring line composition types (all chain and chain-polyester-chain) used in different mooring configurations (catenary, semi-taut and taut) with variable range of mooring line pretensions connected to a floater in shallow and deep water depths are studied. Ratios of fatigue damage results between dynamic and quasi-dynamic results as well as the relation between fatigue damage and statistical characteristics of the line dynamic responses for different line configurations and load cases are investigated in detail.

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Simplifying Methods for Fatigue Analysis of Risers

Volume 3: Structures, Safety, and Reliability ◽

10.1115/omae2019-95386 ◽

2019 ◽

Cited By ~ 1

Author(s):

Luiz O. C. M. Pereira ◽

Paulo M. Videiro ◽

Luís V. S. Sagrilo

Keyword(s):

Fatigue Damage ◽

Computing Time ◽

Fatigue Analysis ◽

State Matrix ◽

Sea State ◽

Mooring Lines ◽

Steel Catenary Riser ◽

Advantages And Disadvantages ◽

Surface Method ◽

Early Design Stages

Abstract This work presents methods for reducing computational costs to estimate fatigue damage in riser structures by simplifying the sea state matrix to be solved in time domain by finite element analyses. Two different methods are proposed: The Equivalent Damage Method (EDM), which is a lump block method with an innovative formulation using vessel linearized response to determine significant sea states; and the Response Surface Method (RSM), which uses results from a few sea states to estimate results for other intermediary scenarios required for the fatigue analysis. Basic assumptions and guidance on how to apply the proposed methods are explained through the text. The methods are used to solve an example of a Steel Catenary Riser (SCR) connected to a Semi-Submersible vessel, resulting in a reduction of almost 80% of the required computing time. Results show accurate values for damage estimates at the top of the riser, and limitations at the touch down zone. Advantages and disadvantages of each method are discussed in detail, demonstrating that they can be used with discretion at early design stages to estimate fatigue damage of risers, umbilicals and mooring lines in general.

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VIM Simulation Method on a Cylindrical Floating Structure

Volume 1: Offshore Technology; Offshore Geotechnics ◽

10.1115/omae2016-54307 ◽

2016 ◽

Cited By ~ 1

Author(s):

Toshifumi Fujiwara

Keyword(s):

Fatigue Damage ◽

Low Frequency ◽

Safety Evaluation ◽

Simulation Method ◽

Offshore Structures ◽

Dominant Factor ◽

Floating Structure ◽

Mooring Lines ◽

Wake Oscillator ◽

Low Frequency Motion

A cylindrical floating structure can basically experience Vortex-induced Motion (VIM) in strong current. Since the VIM on the structure with long term low-frequency motion causes fatigue damage of the structure’s mooring lines and risers, precise VIM assessment is needed for the safety evaluation of them. In the standard of the International Organization for Standardization ISO19901-7, ‘Specific requirements on stationkeeping systems for floating offshore structures and mobile offshore units’, for instance, a concrete method of assessing VIM displacement is not represented in the standard document, though the requirement on the VIM demands to do the assessment on the basis of proper ways. Then in this paper, a VIM simulation method on a floating structure with circular cylinder form, that is, for example a Spar, a MPSO (Mono-column type floating Production Storage and Offloading) and so on, is shown using the wake-oscillator model. Transverse VIM is only treated since it is dominant factor on the fatigue damage of the mooring lines and risers. The assessment quality of the simulation method on the transverse VIM of floaters in current is confirmed by model test data.

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Crossing of Bjørnafjorden - Floating Bridge Concept

IABSE Congress, Stockholm 2016: Challenges in Design and Construction of an Innovative and Sustainable Built Environment ◽

10.2749/stockholm.2016.1911 ◽

2016 ◽

Author(s):

Bruno Villoria

Keyword(s):

Mooring Lines ◽

Southern Shore ◽

Navigation Channel ◽

Floating Bridge

The purpose of this paper is to present the different floating bridge solutions that have been evaluated for the crossing of Bjørnafjorden. It appears to be feasible to place the navigation channel either in the middle of the fjord or in the vicinity of the southern shore. In both scenarios a straight bridge alternative anchored to the seabed and a curved solution without mooring lines are evaluated.

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