A review of structural responses and design of offshore tubular structures subjected to ship impacts

Zhang, Yu; Amdahl, Jørgen

doi:10.1016/j.oceaneng.2018.02.009

Cited by 44 publications

(14 citation statements)

References 104 publications

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“…The soil foundation was not modelled here, as the collision between supply vessel and platform is governed by minor collisions, which are defined as collision events characterised by low-impact velocities, incurring reparable damages to the platform and which does not call for cease of operation [21]. Therefore, the effect of soil characteristics on the damage of the platform is negligible [15,22]. Also, it is assumed that there is enough clearance between platform freeboard and sea level so that there exists no chance of any part of the vessel colliding to the topside module.…”

Section: The Extent Of Structures For Numerical Analysismentioning

confidence: 99%

“…DNV GL [9,10] provided some specific guidelines and general requirements for the determination of structural capacity using NLFEA. Many researchers have performed the structural response analysis of individual tubular members against ship impacts, for instance [11][12][13][14][15]. Notaro et al [16] performed the numerical analysis of OSV collision to a fixed offshore structure, considering both bodies as deformable.…”

Section: Introductionmentioning

confidence: 99%

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Computational models for the structural crashworthiness analysis of a fixed-type offshore platform in collisions with an offshore supply vessel

Mujeeb-Ahmed

Ince

Paik

2020

Thin-Walled Structures

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The aim of this paper was to develop practical modelling techniques for the structural crashworthiness analysis in collisions between a fixed-type offshore platform and an offshore supply vessel (OSV). The computational models used nonlinear finite element method involving large deformations (strains) of both vessel and offshore platform, dynamic effects of material (e.g., strain rate and dynamic fracture strain), and the influence of surrounding waters. The applicability of the modelling techniques was demonstrated with an applied example to collisions between an OSV and a jacket-type offshore platform, where a sensitivity analysis was carried out for different collision parameters (e.g., collision velocities and impact locations). It is concluded that the computational models can ultimately be employed for quantitative risk assessment of fixed-type offshore structures collided with an OSV, which requires to perform the structural crashworthiness analysis.

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Section: The Extent Of Structures For Numerical Analysismentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Computational models for the structural crashworthiness analysis of a fixed-type offshore platform in collisions with an offshore supply vessel

Mujeeb-Ahmed

Ince

Paik

2020

Thin-Walled Structures

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“…An example can be seem from the coupled shipjacket leg collision simulation in Fig. 23 reported in Yu and Amdahl (2018). This motion locking effect will increase the total energy dissipation and make the external dynamic model unconservative.…”

Section: Determination Of the Normal Vector Of The Contact Planementioning

confidence: 99%

Discussion of assumptions behind the external dynamic models in ship collisions and groundings

Zhang

Liu²,

Amdahl

2018

Ships and Offshore Structures

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In the past decades, a prevailing way for the assessment of responses in ship collisions and groundings has been to decouple the problem into two parts: external dynamics and internal mechanics. The external dynamics deals with global motions of the two interacting bodies prior to, during and after the collision. The main outcome of an external dynamics assessment is the energy loss during the collision, which will be dissipated by structural deformations in the assessment of internal mechanics. The decoupled method works well for right-angle collisions in general, but the accuracy can be much less in many scenarios, e.g. skew collisions with small collision angles and collisions with long durations. This is mainly because the assumptions in the decoupled method are violated in the studied cases. This paper reviews the assumptions and simplifications behind the external dynamic models and discusses validity of the assumptions by comparing with coupled simulation results. Decoupled and coupled models in both planar 3DOF and full 6DOF are addressed. Various collision scenarios are studied, including colliding with oblique plates, grounding on a sloping sea floor, crushing into rigid plates with normal vectors misaligned with coordinate axes, and collision with a submersible platform. In some scenarios, cases with different attack angles and impact velocities are simulated. The outcome will help understand potential limitations of the decoupled method, which should be used with care.

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“…Various degradation issues faced by the ageing platform such as corrosion, weld crack, local denting, scour and subsidence [9][10][11][12][13]. These may affect the overall structural integrity of the platform as well as impede its operations as the redundancy and strength of the platform may decrease [14][15][16].…”

Section: Introductionmentioning

confidence: 99%

Structural Integrity of Fixed Offshore Platforms by Incorporating Wave-in-Deck

Azman¹,

Husain²,

Zaki³

et al. 2021

JMSE

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The structural integrity of offshore platforms is affected by degradation issues such as subsidence. Subsidence involves large settlement areas, and it is one of the phenomena that may be experienced by offshore platforms throughout their lives. Compaction of the reservoir is caused by pressure reduction, which results in vertical movement of soils from the reservoir to the mud line. The impact of subsidence on platforms will lead to a gradually reduced wave crest to deck air gap (insufficient air gap) and cause wave-in-deck. The wave-in-deck load can cause significant damage to deck structures, and it may cause the collapse of the entire platform. This study aims to investigate the impact of wave-in-deck load on structure response for fixed offshore structure. The conventional run of pushover analysis only considers the 100-year design crest height for the ultimate collapse. The wave height at collapse is calculated using a limit state equation for the probabilistic model that may give a different result. It is crucial to ensure that the reserve strength ratio (RSR) is not overly estimated, hence giving a false impression of the value. This study is performed to quantify the wave-in-deck load effects based on the revised RSR. As part of the analysis, the Ultimate Strength for Offshore Structures (USFOS) software and wave-in-deck calculation recommended by the International Organization for Standardization (ISO) as practised in the industry is adopted to complete the study. As expected, the new revised RSR with the inclusion of wave-in-deck load is lower and, hence, increases the probability of failure (POF) of the platform. The accuracy and effectiveness of this method will assist the industry, especially operators, for decision making and, more specifically, in outlining the action items as part of their business risk management.

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A review of structural responses and design of offshore tubular structures subjected to ship impacts

Cited by 44 publications

References 104 publications

Computational models for the structural crashworthiness analysis of a fixed-type offshore platform in collisions with an offshore supply vessel

Computational models for the structural crashworthiness analysis of a fixed-type offshore platform in collisions with an offshore supply vessel

Discussion of assumptions behind the external dynamic models in ship collisions and groundings

Structural Integrity of Fixed Offshore Platforms by Incorporating Wave-in-Deck

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