Recent Advances in Floating Structures

A special issue of Journal of Marine Science and Engineering (ISSN 2077-1312). This special issue belongs to the section "Coastal Engineering".

Deadline for manuscript submissions: closed (30 November 2022) | Viewed by 25535

Special Issue Editors

Department of Civil Engineering and Energy Technology, Oslo Metroplitan University, Oslo, Norway
Interests: structural dynamics; very large floating structures; floating bridge; floating photovoltaic system; high-speed rail system; vehicle dynamics
School of Civil Engineering, The University of Queensland, St Lucia, QLD 4072, Australia
Interests: offshore floating fish farms; infrastructure for offshore seaweed farms; development of new structural models for analysis
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear colleagues,

Floating structures are an attractive solution to create space for congested coastal areas, connect land parcels separated by water bodies and support industrial and aquaculture activities in the sea. They have many advantages, such as being environmentally friendly, scalable and removable, and immune to the rising water level due to global climate change. Advancements in technology and growing demands have led to a growth in activities geared towards deeper and harsher water environments. This brings difficulties and new challenges that have not been encountered previously. The advancement of knowledge and theory as well as modelling and experimental skills have become critical to reduce risk and ensure safe functionalities. Moreover, there is an imperative need to develop innovative design concepts, efficient structural and station-keeping systems, and durable and cost-effective materials to achieve sustainable and productive goals.

In the above context, this Special Issue invites original scientific contributions and review articles on the broad aspects of floating structures for both inland, coastal and offshore uses. Various applications of the floating structural technology include but are not limited to:

  • Aquaculture engineering;
  • Desalination plants;
  • Floating breakwaters;
  • Floating bridges and submerged tunnels;
  • Floating platforms;
  • Hydrocarbon and LNG storage facilities;
  • Renewable energy;
  • Residential and recreational facilities;
  • Floating piers and harbours

Dr. Jian Dai
Prof. Dr. Bernt J Leira
Prof. Dr. Chien Ming Wang
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Journal of Marine Science and Engineering is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2600 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • environmental loads
  • conceptual design
  • structural solution
  • station-keeping system
  • material
  • hydrodynamic behaviour
  • numerical modelling
  • experiment

Published Papers (10 papers)

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Research

Jump to: Review

17 pages, 9787 KiB  
Article
Offshore, Unmanned Auto-Leveling Sea-Surface Drifting Platform with Compact Size
by Zonglai Mo, Kexiang Li, Kefeng Xie, Jun Li and Yanjun Li
J. Mar. Sci. Eng. 2023, 11(3), 506; https://0-doi-org.brum.beds.ac.uk/10.3390/jmse11030506 - 26 Feb 2023
Viewed by 1338
Abstract
This paper proposes an offshore, unmanned auto-leveling sea-surface drifting platform, with a compact size of 0.7 m in diameter, used for obtaining air-sea interface environmental parameters. The platform was designed based on the parallel mechanism with limited degrees of freedom. The mechanical structure, [...] Read more.
This paper proposes an offshore, unmanned auto-leveling sea-surface drifting platform, with a compact size of 0.7 m in diameter, used for obtaining air-sea interface environmental parameters. The platform was designed based on the parallel mechanism with limited degrees of freedom. The mechanical structure, control system hardware, and software of the principal prototype are introduced. A ground-based device was developed to simulate wave disturbance, based on which the static and dynamic simulation experiments were carried out. Experimental results show that the auto-leveling system can achieve real-time leveling against the angle deviation induced by waves, with a leveling accuracy of 0.2° in a simulated wave with an angle of 12°, which meets the requirements of observation equipment. Full article
(This article belongs to the Special Issue Recent Advances in Floating Structures)
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18 pages, 7340 KiB  
Article
Efficiency and Wave Run-Up of Porous Breakwater with Sloping Deck
by Mengmeng Han and Chien Ming Wang
J. Mar. Sci. Eng. 2022, 10(12), 1896; https://0-doi-org.brum.beds.ac.uk/10.3390/jmse10121896 - 05 Dec 2022
Cited by 2 | Viewed by 1381
Abstract
In order to protect fragile shoreline and coastal assets during extreme storms, a combined floating breakwater-windbreak has been proposed to reduce both wind and wave energies in the sheltered area. The 1 km-long breakwater has a porous hull with internal tubes to allow [...] Read more.
In order to protect fragile shoreline and coastal assets during extreme storms, a combined floating breakwater-windbreak has been proposed to reduce both wind and wave energies in the sheltered area. The 1 km-long breakwater has a porous hull with internal tubes to allow free passage of water; thereby further dissipating wave energy. The deck of the structure is designed to have a slope of 25 degrees facing the upstream side, and arrays of cylindrical tubes are placed on the sloping deck to form a windbreak. A reduced-scale (1:50) model test was carried out in a wave flume to examine wave sheltering performance under significant wave heights Hs = 3.0 m to 7.5 m and peak wave periods Tp = 9.4 s to 14 s sea states. Both regular and random wave conditions with different wave heights were considered. It is found that transmission coefficients ranging from 0.4 to 0.6 can be achieved under tested wave conditions. Porous breakwater hull increases the wave dissipation coefficients and is effective in reducing the wave reflection at the upstream side. The wave run-up length is dependent on the Iribarren number if the reduction induced by vertical freeboard is considered. Based on experimental data, empirical formulae have been proposed to predict the wave run-up responses in regular waves, probability of non-zero wave run-up occurrence, modified Weibull distribution of the wave run-up peaks and extreme wave run-up in random waves. Full article
(This article belongs to the Special Issue Recent Advances in Floating Structures)
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19 pages, 3467 KiB  
Article
Hydrodynamic Analysis of a Modular Integrated Floating Structure System Based on Dolphin-Fender Mooring
by Nianxin Ren, Yuekai Yu, Xiang Li and Jinping Ou
J. Mar. Sci. Eng. 2022, 10(10), 1470; https://0-doi-org.brum.beds.ac.uk/10.3390/jmse10101470 - 10 Oct 2022
Cited by 1 | Viewed by 1826
Abstract
For both the expansion of important islands/reefs and the development of marine resources in South China Sea, a modular integrated floating structure (MIFS) system with tidal self-adaptation dolphin-fender mooring (DFM) has been proposed. The DFM, coupled with wave energy converters (WEC), can serve [...] Read more.
For both the expansion of important islands/reefs and the development of marine resources in South China Sea, a modular integrated floating structure (MIFS) system with tidal self-adaptation dolphin-fender mooring (DFM) has been proposed. The DFM, coupled with wave energy converters (WEC), can serve as an anti-motion system. Considering both the modules’ hydrodynamic interaction effect and the connectors’ mechanical coupling effect, both dynamic responses of the MIFS system and the WEC’s output power characteristics were investigated under typical sea conditions. Based on the comprehensive consideration of key factors (safety, economy, and comfort), the effects of both the DFM and module connectors were systematically studied for the MIFS system. Preliminarily optimal design parameters of corresponding connectors and WECs were suggested. The security of the MIFS system under extreme sea conditions was checked, and a promising survival strategy has been proposed. In addition, the modular expansion scheme of the MIFS system was further discussed, and the results indicated that the proposed MIFS system shows good expansibility. The WEC can not only improve both dynamic responses and the comfort of inner modules, but also make considerable wave energy contributions. Full article
(This article belongs to the Special Issue Recent Advances in Floating Structures)
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20 pages, 10425 KiB  
Article
Experimental Investigation of the Performance of a Tuned Heave Plate Energy Harvesting System for a Semi-Submersible Platform
by Kun Liu, Haizhi Liang, Jingpin Ou, Jiawei Ye and Dongjiao Wang
J. Mar. Sci. Eng. 2022, 10(1), 45; https://0-doi-org.brum.beds.ac.uk/10.3390/jmse10010045 - 01 Jan 2022
Cited by 1 | Viewed by 1437
Abstract
Heave plates are widely used for improving the sea keeping performance of ocean structures. In this paper, a novel tuned heave plate energy harvesting system (THPEH) is presented for the motion suppression and energy harvesting of a semi-submersible platform. The heave plates are [...] Read more.
Heave plates are widely used for improving the sea keeping performance of ocean structures. In this paper, a novel tuned heave plate energy harvesting system (THPEH) is presented for the motion suppression and energy harvesting of a semi-submersible platform. The heave plates are connected to the platform though a power take-off system (PTO) and spring supports. The performance of the THPEH was investigated through forced oscillation tests of a 1:20 scale model. Firstly, the hydrodynamic parameters of the heave plate were experimentally studied under different excitation motion conditions, and a force model of the power take-off system was also established through a calibration test. Then, the motion performance, control performance, and energy harvesting performance of the THPEH subsystem were systematically studied. The effects of the tuned period and PTO damping on the performance of the THPEH were analyzed. Finally, a comparison between the conventional fixed heave plate system and THPEH was carried out. The results show that a properly designed THPEH could consume up to 2.5 times the energy from the platform motion compared to the fixed heave plate system, and up to 80% of the consumed energy could be captured by the PTO system. This indicates that the THPEH could significantly reduce the motion of the platform and simultaneously provide considerable renewable energy to the platform. Full article
(This article belongs to the Special Issue Recent Advances in Floating Structures)
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30 pages, 9283 KiB  
Article
Hydrodynamic Behaviour of Floating Polygonal Platforms under Wave Action
by Jeong Cheol Park and Chien Ming Wang
J. Mar. Sci. Eng. 2021, 9(9), 923; https://0-doi-org.brum.beds.ac.uk/10.3390/jmse9090923 - 25 Aug 2021
Cited by 6 | Viewed by 1595
Abstract
The hydrodynamic behaviour of floating regular polygonal platforms under wave action was studied by conducting parametric studies. Considering triangular, square, hexagonal, and circular platforms of similar size and draft, the results show that their added mass, radiation damping, and RAOs are similar. However, [...] Read more.
The hydrodynamic behaviour of floating regular polygonal platforms under wave action was studied by conducting parametric studies. Considering triangular, square, hexagonal, and circular platforms of similar size and draft, the results show that their added mass, radiation damping, and RAOs are similar. However, the wave exciting forces are slightly different, particularly the horizontal forces. The polygonal platforms oriented with one of its corners in line with the prevailing wave direction can lead to a reduction in the horizontal force on the platform, a feature that helps in reducing the cost of a mooring system. Moreover, such oriented platforms are able to disperse the waves better in multiple directions and hence will not pose problems for ships or marine vessels passing by the platform on the weather side. Thus, the orientation of a polygonal platform is an important design consideration. From the comparison study among different polygonal platforms, their wave attenuation performances are slightly similar. The hydrodynamic analyses performed herein for the parametric studies were sped up considerably by using a significantly lesser number of Fourier coefficient sets for the series functions that define the velocity potentials when compared to those used by previous researchers in their analytical approaches. The adoption of the radius function defined by cosine-type radial perturbation does not only generate the geometric boundaries of polygonal platforms, but it also simplifies the formulation and quickens the computations. Full article
(This article belongs to the Special Issue Recent Advances in Floating Structures)
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18 pages, 21243 KiB  
Article
Effectiveness of Floating Breakwater in Special Configurations for Protecting Nearshore Infrastructures
by Chi Zhang and Allan R. Magee
J. Mar. Sci. Eng. 2021, 9(7), 785; https://0-doi-org.brum.beds.ac.uk/10.3390/jmse9070785 - 20 Jul 2021
Cited by 4 | Viewed by 3911
Abstract
This paper investigates the effectiveness of floating breakwaters consisting of two barges (L-shape), three barges (U-shape), four barges (barge frame), and conventional single floating breakwater. The floating breakwaters of different spatial layouts have sheltered internal gaps/moonpools when compared to their conventional counterparts. The [...] Read more.
This paper investigates the effectiveness of floating breakwaters consisting of two barges (L-shape), three barges (U-shape), four barges (barge frame), and conventional single floating breakwater. The floating breakwaters of different spatial layouts have sheltered internal gaps/moonpools when compared to their conventional counterparts. The motions of these floating breakwaters and their effectiveness in wave transmission and motion reduction of the protected floating bodies are evaluated. The study is conducted based on a subsystem of a floating hydrocarbon storage facility that combines a floating breakwater with two floating tanks, studied previously. Numerical models based on linear potential flow theory are built for these floating breakwaters with and without the floating tanks. The numerical models of the barge frame are validated through laboratory experiments, and the dipole damping lids to reduce the resonant fluid motions in the gaps/moonpools are calibrated with experimental results. The L-shape floating breakwater is found effective in reducing wave transmissions without the presence of the floating tanks, while the barge frame is the most effective in the motion reduction of the floating tanks. In addition, significant fluid resonant motions are identified for all investigated floating breakwaters, including the conventional one. Orienting the structure obliquely can improve the performance of the floating breakwaters of special configurations, especially the barge frame. The results and findings show the importance of considering the protected floating structures in the analysis when designing floating breakwaters for many types of marine structures, including floating fish farms and floating cities in coastal waters. Full article
(This article belongs to the Special Issue Recent Advances in Floating Structures)
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19 pages, 7223 KiB  
Article
Effect of Modelling Inhomogeneous Wave Conditions on Structural Responses of a Very Long Floating Bridge
by Jian Dai, Christos Stefanakos, Bernt J. Leira and Hagbart Skage Alsos
J. Mar. Sci. Eng. 2021, 9(5), 548; https://0-doi-org.brum.beds.ac.uk/10.3390/jmse9050548 - 19 May 2021
Cited by 8 | Viewed by 2101
Abstract
Floating bridges are suitable for connecting land parcels separated by wide and deep waterbodies. However, when the span of the crossing becomes very long, the water environment exhibits inhomogeneities which introduce difficulties to the modelling, analysis and design of the bridge structure. The [...] Read more.
Floating bridges are suitable for connecting land parcels separated by wide and deep waterbodies. However, when the span of the crossing becomes very long, the water environment exhibits inhomogeneities which introduce difficulties to the modelling, analysis and design of the bridge structure. The wave inhomogeneity may be described by means of field measurement and/or numerical simulations. Both approaches face complications when the resolution is much refined. It is thus important to examine the effect of the resolution related to the modelling of inhomogeneous waves on the global structural responses. In this study, a hypothetical crossing at the Sulafjord is chosen, and the wave environment in the year 2015 at 10 positions along the crossing is numerically computed. Next, different inhomogeneous wave conditions are established based on the wave data at 3, 5, and 10 positions, respectively. Time-domain simulations are conducted to examine the effect of different modelling approaches of the inhomogeneous wave condition on the global responses of a long, straight and side-anchored floating bridge. Full article
(This article belongs to the Special Issue Recent Advances in Floating Structures)
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17 pages, 5931 KiB  
Article
Hydrodynamic Analysis of a Modular Floating Structure with Tension-Leg Platforms and Wave Energy Converters
by Nianxin Ren, Hongbo Wu, Kun Liu, Daocheng Zhou and Jinping Ou
J. Mar. Sci. Eng. 2021, 9(4), 424; https://0-doi-org.brum.beds.ac.uk/10.3390/jmse9040424 - 14 Apr 2021
Cited by 3 | Viewed by 2213
Abstract
This work presents a modular floating structure, which consists of five inner tension-leg platforms and two outermost wave energy converters (denoted as MTLPW). The hydrodynamic interaction effect and the mechanical coupling effect between the five inner tension-leg platforms (TLP) and the two outermost [...] Read more.
This work presents a modular floating structure, which consists of five inner tension-leg platforms and two outermost wave energy converters (denoted as MTLPW). The hydrodynamic interaction effect and the mechanical coupling effect between the five inner tension-leg platforms (TLP) and the two outermost wave energy converters (WEC) are taken into consideration. The effects of the connection modes and power take-off (PTO) parameters of the WECs on the hydrodynamic performance of the MTLPW system are investigated under both operational and extreme sea conditions. The results indicate that the hydrodynamic responses of the MTLPW system are sensitive to the connection type of the outermost WECs. The extreme responses of the bending moment of connectors depend on the number of continuously fixed modules. By properly utilizing hinge-type connectors to optimize the connection mode for the MTLPW system, the effect of more inner TLP modules on the hydrodynamic responses of the MTLPW system can be limited to be acceptable. Therefore, the MTLPW system can be potentially expanded to a large degree. Full article
(This article belongs to the Special Issue Recent Advances in Floating Structures)
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17 pages, 9554 KiB  
Article
Representative Transmission Coefficient for Evaluating the Wave Attenuation Performance of 3D Floating Breakwaters in Regular and Irregular Waves
by Huu Phu Nguyen, Jeong Cheol Park, Mengmeng Han, Chien Ming Wang, Nagi Abdussamie, Irene Penesis and Damon Howe
J. Mar. Sci. Eng. 2021, 9(4), 388; https://0-doi-org.brum.beds.ac.uk/10.3390/jmse9040388 - 06 Apr 2021
Cited by 8 | Viewed by 2724
Abstract
Wave attenuation performance is the prime consideration when designing any floating breakwater. For a 2D hydrodynamic analysis of a floating breakwater, the wave attenuation performance is evaluated by the transmission coefficient, which is defined as the ratio between the transmitted wave height and [...] Read more.
Wave attenuation performance is the prime consideration when designing any floating breakwater. For a 2D hydrodynamic analysis of a floating breakwater, the wave attenuation performance is evaluated by the transmission coefficient, which is defined as the ratio between the transmitted wave height and the incident wave height. For a 3D breakwater, some researchers still adopted this evaluation approach with the transmitted wave height taken at a surface point, while others used the mean transmission coefficient within a surface area. This paper aims to first examine the rationality of these two evaluation approaches via verified numerical simulations of 3D heave-only floating breakwaters in regular and irregular waves. A new index—a representative transmission coefficient—is then presented for one to easily compare the wave attenuation performances of different 3D floating breakwater designs. Full article
(This article belongs to the Special Issue Recent Advances in Floating Structures)
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Review

Jump to: Research

29 pages, 4581 KiB  
Review
State-of-the-Art Review of Vortex-Induced Motions of Floating Offshore Wind Turbine Structures
by Decao Yin, Elizabeth Passano, Fengjian Jiang, Halvor Lie, Jie Wu, Naiquan Ye, Svein Sævik and Bernt J. Leira
J. Mar. Sci. Eng. 2022, 10(8), 1021; https://0-doi-org.brum.beds.ac.uk/10.3390/jmse10081021 - 26 Jul 2022
Cited by 9 | Viewed by 3292
Abstract
The motivation for this study is the fast development of floating offshore wind energy and the immature methodology and engineering practice related to predictions of vortex-induced motions (VIM). Benefiting from the oil and gas industry, in the past several decades, extensive knowledge and [...] Read more.
The motivation for this study is the fast development of floating offshore wind energy and the immature methodology and engineering practice related to predictions of vortex-induced motions (VIM). Benefiting from the oil and gas industry, in the past several decades, extensive knowledge and experience on vortex-induced vibrations (VIV) on slender marine structures has been gained. As the learnings from these efforts should be transferred and adapted to the renewable energy industry, a state-of-the-art review on influential VIM research has been carried out in this paper, focusing on: (1) engineering practice, (2) model tests, (3) numerical calculation, and (4) field measurement. Engineering gaps and potential research topics are identified as future work. Full article
(This article belongs to the Special Issue Recent Advances in Floating Structures)
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