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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 (31 October 2022) | Viewed by 25918

Image courtesy of Dr. Kangsu Lee and Prof. Dr. Chang Yong Song

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Special Issue Editors

Dr. Kangsu Lee

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Guest Editor

Korea Research Institute of Ships & Ocean Engineering, Yuseong-gu, Daejon, Republic of Korea
Interests: offshore structural analysis; finite element method; hydroelasticity; nonlinear mechanics
Special Issues, Collections and Topics in MDPI journals

Prof. Dr. Chang Yong Song

E-Mail Website
Guest Editor

Department of Naval Architecture & Ocean Engineering, Mokpo National University, Joennam 58554, Republic of Korea
Interests: soft computing; optimization; probabilistic design methodology; AI application to design
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

This Special Issue covers research topics related to the design and analysis of offshore structures. All theoretical, analytical, numerical, and experimental research, as well as review papers and case studies of engineering applications for offshore structures are warmly invited. Various offshore structures can be included, such as fixed, floating, movable, jack-up, and hybrid. This Special Issue aims at gathering the most promising research in this area. Contributions focused on new challenges are particularly encouraged. A rapid reviewing process and open-access publication will be provided for high-quality papers on the following topics:

Hydrodynamic analysis of offshore structures;
Structural design and analysis of offshore structures;
Mooring system analysis;
Local strength analysis of welded joint;
Hydroelastic analysis of very large floating structures;
Structural health monitoring of offshore structures;
Reliability-based structural design and analysis;
Fluid–structure interactions;
Structure–soil interactions;
Transportation and installation analysis of offshore structures;
Fire and explosion analysis of offshore structures;
Fatigue and fracture analysis of offshore structures.

Dr. Kangsu Lee
Prof. Dr. Chang Yong Song
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

fixed offshore structure
floating offshore structure
mooring system
hydroelasticity
hydrodynamic analysis
structural analysis
local strength
transportation and installation
fluid–structure interaction
fire and explosion
fatigue and fracture

Related Special Issue

Design and Analysis of Offshore Structures II in Journal of Marine Science and Engineering

Published Papers (12 papers)

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Research

15 pages, 3935 KiB

Open AccessArticle

Mathematical Model of an Offshore Friction Pile in Multilayered Saturated Soils

by Deyong Guan and Kun Meng

J. Mar. Sci. Eng. 2022, 10(12), 1886; https://doi.org/10.3390/jmse10121886 - 04 Dec 2022

Cited by 1 | Viewed by 1070

Abstract

In this paper, an analytical methodology is proposed to study the vibration of an offshore friction pile embedded in multilayered saturated viscoelastic soils by combining Biot’s saturated wave propagation theory, Novak’s plane-strain model, and the fictitious saturated soil pile model. The corresponding semi-analytical solution for the dynamic response of the pile is developed considering the heterogeneity, porosity, and limited thickness of the soils. The approach and relevant solution presented are validated by comparisons with existing solutions. Furthermore, numerical instances are used to investigate the influences of the porosity and heterogeneity of the saturated soils around and beneath the pile on the vibration of the pile. The findings from this paper provide a theoretical reference for a comprehensive understanding of the wave propagation characteristics of a friction pile embedded in heterogeneous saturated soil with limited thickness. Full article

(This article belongs to the Special Issue Design and Analysis of Offshore Structures)

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21 pages, 12546 KiB

Open AccessArticle

Development of a Time-Domain Simulation Code for Cross-Flow Vortex-Induced Vibrations of a Slender Structure with Current Using the Synchronization Model

by Seunghoon Oh, Eunsoo Kim and Dongho Jung

J. Mar. Sci. Eng. 2022, 10(12), 1815; https://doi.org/10.3390/jmse10121815 - 24 Nov 2022

Viewed by 1353

Abstract

In this paper, the numerical analysis method for the cross-flow vortex-induced vibration (CF VIV) analysis based on the proposed procedure for CF VIV analysis of slender structures is developed. In order to consider the changes in the incoming flow according to the static configuration of the slender structures due to the current, the proposed procedure has three stages. A slender structure is modeled as the lumped-mass line, and the dynamic relaxation method known as the numerical technique for a slender structure with large geometric nonlinearity is applied in the static analysis. The comparison studies with a commercial program are carried out to validate the developed code. The vortex-induced force on slender structures is considered with the synchronization model. To verify the developed CF VIV analysis procedure and numerical method for a slender structure, VIV analysis of the tensioned flexible risers under a uniform and shear current is performed. The simulated results of CF RMS displacement show good agreement with the results of the model test It is found that a tensioned riser vibrates with one dominant frequency in resonance with the nth mode, even though multi-frequencies components of the vortex shedding along the riser due to the shear current occurs. Full article

(This article belongs to the Special Issue Design and Analysis of Offshore Structures)

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18 pages, 6474 KiB

Open AccessArticle

A Study on the Vortex Induced Vibration of a Cylindrical Structure with Surface Bulges

by Haoyuan Xu, Jie Wang, Zhiqing Li, Kaihua Liu, Jiawei Yu and Bo Zhou

J. Mar. Sci. Eng. 2022, 10(11), 1785; https://doi.org/10.3390/jmse10111785 - 19 Nov 2022

Cited by 3 | Viewed by 1801

Abstract

Inspired by the cactus in nature, a cactus-like cross-sectional structure was proposed to achieve the VIV suppression. The VIV of the elastically mounted cylinder was realized based on the ANSYS Fluent and User Defined Function (UDF). The dynamic motion of the cylinder was [...] Read more.

β

method. The in-house code was first validated by studying the 2DOF VIV of a circular cylinder with small mass ratio over the range

U^{*} = 2 ~ 13

, and the results agree well with the published literature. Then, the performance of surface bulge on VIV suppression was studied and four different coverage ratios (CR) were considered, i.e., 0%, 20%, 33%, and 40%. The VIV of a bulged cylinder can be effectively suppressed. CR20 performs the best in VIV suppression and the suppression efficiency in streamwise and transverse direction are 44.6% and 63.1%, respectively. The mechanism of surface bulge on the VIV suppression is the shift of separation point of the shear layer and vortices form between the surface bulges. Full article

(This article belongs to the Special Issue Design and Analysis of Offshore Structures)

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13 pages, 2755 KiB

Open AccessArticle

An Improved Version of ETS-Regression Models in Calculating the Fixed Offshore Platform Responses

by Sayyid Zainal Abidin Syed Ahmad, Mohd Khairi Abu Husain, Noor Irza Mohd Zaki, Nurul ‘Azizah Mukhlas and Gholamhossein Najafian

J. Mar. Sci. Eng. 2022, 10(11), 1727; https://doi.org/10.3390/jmse10111727 - 11 Nov 2022

Viewed by 1182

Abstract

An offshore structural design should accurately calculate wave loads and structural responses acting on slender cylinders. The hydrodynamic drag-dominated force was always challenging, hence the hydrodynamic wave loading became a complex solution; it led to a nonlinear relation between the wave force and responses caused by the diffracted and radiated waves, which was included in Morison’s equation. For more consistency in the structural assessment, the linearised drag–inertia force was considered in model development, such as an improved version of the efficient time simulation regression (ETS-Reg) procedure that was introduced. The study aimed to improve the prediction of structural responses using the predetermined linear, polynomial, and cubic regression models. These simulations were performed focusing on high sea state conditions without wave-induced current effects. In order to evaluate the level of accuracy, the recent ETS-Reg models were compared and validated using the Monte Carlo time simulation (MCTS) method. An amended ETS-Reg model, known as the ETS-Reg_LR model, was also compared with the previous results obtained using the conventional ETS-Reg models (ETS-Reg_SE), leading to better structural response calculations. Full article

(This article belongs to the Special Issue Design and Analysis of Offshore Structures)

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15 pages, 4577 KiB

Open AccessArticle

Fluid–Structure Interaction Analysis and Verification Test for Soil Penetration to Determine the Burial Depth of Subsea HVDC Cable

by Chang-Yong Song

J. Mar. Sci. Eng. 2022, 10(10), 1453; https://doi.org/10.3390/jmse10101453 - 08 Oct 2022

Cited by 1 | Viewed by 1195

Abstract

Recently, there have been frequent reports of subsea cable breakage accidents caused by the drop of an anchor pile for aquaculture works involving subsea cables for high-voltage direct current (HVDC) transmission embedded in the southwest sea of Korea. To determine the burial depth that can ensure the safety of subsea HVDC cables embedded under the seabed from the drop of anchor files, the soil penetration characteristics of anchor piles should be reasonably estimated. In the present study, the penetration characteristics of anchor piles into the soil under which subsea HVDC cables are embedded were evaluated using numerical simulations and field verification tests. The numerical simulation for the soil penetration phenomena of anchor piles was carried out using the fluid–structure interaction analysis method using the general purpose nonlinear finite element analysis code based on explicit time integration. Regarding the soil into which anchor piles penetrate, three types of soil—a clay layer, a sand layer, and a clay–sand mixed layer—were considered, which are the representative soil types in the southwest sea of Korea, where many subsea HVDC cables have been embedded. The result of fluid–structure interaction analysis showed that the maximum penetration into the clay layer was higher than that into the sand layer and the clay–sand mixed layer by 86.3% and 36.4% or more, respectively. The error rates of the field verification test and the fluid–structure interaction analysis were found to be 9.8%, 2.4%, and 2.4% in the clay layer, the sand layer, and the clay–sand mixed layer, respectively, which were found to be reasonable levels when considering that it was the numerical simulation for the soil penetration of an anchor pile resulting from drop impacts. The penetration depths of anchor piles were found to be the deepest in the clay layer, showing values of 3.9 to 4.1 m, and those in the sand layer were the shallowest, showing values of 1.9 to 2.1 m. Full article

(This article belongs to the Special Issue Design and Analysis of Offshore Structures)

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12 pages, 8109 KiB

Open AccessArticle

Numerical Investigation of the Ultimate Strength of D-Ring Devices and Deck Structures

by Woongshik Nam, Sung-Ju Park and Kookhyun Kim

J. Mar. Sci. Eng. 2022, 10(7), 952; https://doi.org/10.3390/jmse10070952 - 11 Jul 2022

Cited by 2 | Viewed by 1810

Abstract

An accurate prediction of the ultimate strength of lashing devices and deck structures is important to ensure the safety of the crews and carrying ships. In this study, finite element analysis using ABAQUS/implicit was performed to investigate the ultimate strength of D-ring devices subjected to various external loads. The resistance of deck plates to which the D-ring devices were clamped was also analyzed numerically, considering the effects of the plate thickness and corrosion wastage. The resultant force-displacement relationship of the devices and the deck plate was investigated from the simulations and the threshold was determined by means of the tangent interaction method. The numerical results were compared with the Cargo Stowage and Securing Code proposed by the International Marine Organization and the results showed that the code predicts conservative ultimate strength of the D-ring devices in most cases. The deck plate with a thickness of 6 mm should have a local stiffener to increase structural strength whereas corrosion wastage has negligible effect on the deck strength. The numerical analysis verified the feasibility of predicting the ultimate strength of D-ring devices and deck structures. Nevertheless, the need for further experimental study is acknowledged to validate the feasibility of the numerical results. Full article

(This article belongs to the Special Issue Design and Analysis of Offshore Structures)

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14 pages, 26452 KiB

Open AccessArticle

Preliminary Design and Dynamic Response of Multi-Purpose Floating Offshore Wind Turbine Platform: Part 1

by Shamsan Alsubal, Mohd S. Liew and Lim Eu Shawn

J. Mar. Sci. Eng. 2022, 10(3), 336; https://doi.org/10.3390/jmse10030336 - 28 Feb 2022

Cited by 3 | Viewed by 2736

Abstract

Floating offshore wind turbine foundations are based on platforms operated by the oil and gas industry. However, they are designed and optimized to meet the wind turbines’ operating criteria. Although Malaysia is considered a low-wind-speed country, there are some locations facing the South China Sea that are found to be feasible for wind energy harnessing. The average daily wind speed may reach up to 15 m/s. Therefore, designing a cost-effective platform that can operate in Malaysian waters which has less severe environmental conditions compared to the North Sea would be a prudent undertaking. In this study, a new design of a multi-purpose floating offshore wind turbine platform (Mocha-TLP) is presented. In addition, the dynamic response of the platform to wave loads was investigated using the Navier–Stokes code STAR CCM+ developed by CD-adapco. Moreover, free-oscillation tests were performed to determine the natural periods of the platform. Three approaching wave cases and two wave conditions (WC) were considered. The results show that the natural periods of the platforms were within the recommended range for pitch, roll, yaw, heave, sway and surge motions. The platform was stable in rotational motion within the three cases. However, it experienced a noticeable surge motion which was more critical with wave condition one (WC1) since the wavelength equalled the length of the structure. The dynamic response of the platform to wave loads wase minimal and within the operational requirements for wind turbines. Full article

(This article belongs to the Special Issue Design and Analysis of Offshore Structures)

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20 pages, 9058 KiB

Open AccessArticle

Mechanical Behavior of the Rock-Concrete Interface for a Bridge Anchorage Structure Using Discrete Element Method

by Zhen Cui, Maochu Zhang and Qian Sheng

J. Mar. Sci. Eng. 2022, 10(2), 221; https://doi.org/10.3390/jmse10020221 - 07 Feb 2022

Cited by 2 | Viewed by 1666

Abstract

Traditionally, the numerical simulation work of a bridge gravity anchorage structure is performed with a continuous method, such as the finite element method (FEM). However, since the rock mass and gravity anchorage structure are assumed to be continuous in the FEM, the interaction between the rock mass foundation and the concrete of the anchorage is not frequently considered. This paper aims to investigate the problem of the interaction between the rock mass foundation and the concrete of the anchorage. The discrete element method (DEM), which has been verified to be suitable for the modelling of contact problems of discrete blocks, is introduced in this paper to simulate the mechanical behavior of the rock-concrete system of the gravity anchorage structure and its rock mass foundation. Based on the in-situ scale model test for a bridge, the mechanical behavior of the rock-concrete interface was discussed with the DEM method. With the calibrated DEM model, the displacement of the foundation rock mass, contact stresses, and yield state on the rock-concrete interface were numerically investigated. The anti-sliding effect of the keyway and the step at the bottom of the gravity anchorage structure was analyzed. The results show that the anchorage deformation under the design conditions is basically characterized by the rigid rotation around the keyway of platform #2, and that such rotation subsequently affects the anti-shear capacity of the entire gravity anchorage to a large extent. The anchorage scale model could remain stable under the design lateral load such that the rock-concrete interface would remain intact and sufficient shear resistance could be provided by the keyway and steps. Full article

(This article belongs to the Special Issue Design and Analysis of Offshore Structures)

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12 pages, 6991 KiB

Open AccessArticle

Numerical Study on the Tank Heel Determination Using Smoothed Particle Hydrodynamics

by Kyu-Sik Park, Hung-Truyen Luong and Joonmo Choung

J. Mar. Sci. Eng. 2021, 9(9), 1016; https://doi.org/10.3390/jmse9091016 - 17 Sep 2021

Viewed by 2777

Abstract

Tank heel minimization is a significant issue in the design of LNG fuel tanks because it is associated with stable suction pump operation and thermal shock requirements during LNG bunkering. This study examined how the LNG tank heel is minimized, maintaining a suction pump fully submerged in LNG during dynamic vessel motion. The study assumed two LNG fuel tanks mounted on the forward deck of a 50,000 deadweight class oil product carrier. Information on the dimensions and shape of the LNG fuel tank was determined from Wartsila’s brochure, and the specifications of Vanzetti’s suction pump were referred to. The LNG fuel tank and LNG heel were modeled as rigid elements and hydrodynamically smoothed-particles, respectively. The number of particles could be determined by performing even keel analyzes by adding or subtracting particles until the target head was satisfied under the gravity load. To simulate the motion of the LNG fuel tank, the pitch and roll periods and amplitudes of the ship were calculated using the DNV classification rules. Visual observations of the dynamic flow during the pitch and roll motions with respect to the ship’s center of mass showed that the roll motion was more critical from the viewpoint of the LNG heel than the pitch motion. After performing the simulations for three cycles of roll and pitch motions, the suction pump submergence was reviewed in the last cycle. Under the conditions assumed in this study, a filling ratio of 15% was determined as the minimum LNG tank heel. Although the LNG heel has customarily been determined, the LNG heel needs to be determined through hydrodynamic analyses of each vessel because it depends on the shape of the fuel tank and the vessel motion characteristics. Full article

(This article belongs to the Special Issue Design and Analysis of Offshore Structures)

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15 pages, 3021 KiB

Open AccessArticle

The Quasi-Static Response of Moored Floating Structures Based on Minimization of Mechanical Energy

by Chun Bao Li, Mingsheng Chen and Joonmo Choung

J. Mar. Sci. Eng. 2021, 9(9), 960; https://doi.org/10.3390/jmse9090960 - 03 Sep 2021

Cited by 9 | Viewed by 3015

Abstract

It is essential to design a reasonable mooring line length that ensures quasi-static responses of moored floating structures are within an acceptable level, and that reduces the cost of mooring lines in the overall project. Quasi-static responses include the equilibrium position and the line tension of a moored floating structure (also called the mean value in a dynamic response), etc. The quasi-static responses derived by the classic catenary equation cannot present mooring–seabed interaction and hydrodynamic effects on a mooring line. While a commercial program can predict reasonable quasi-static responses, costly modeling is required. This motivated us to propose a new method for predicting quasi-static responses that minimizes the mechanical energy of the whole system based on basic geometric parameters, and that is easy to implement. In this study, the mechanical energy of moored floating structures is assumed to be the sum of gravitational–buoyancy potential energy, kinetic energy induced by drag forces, and spring potential energy derived by line tension. We introduce fundamental theoretical background for the development of the proposed method. We investigate the effect of quasi-static actions on mooring response, comparing the proposed method’s results with those from the catenary equation and ABAQUS software. The study reveals the shortcomings of the catenary equation in offshore applications. We also compare quasi-static responses derived by the AQWA numerical package with the results calculated from the proposed method for an 8 MW WindFloat 2 type of platform. Good agreement was drawn between the proposed method and AQWA. The proposed method proves more timesaving than AQWA in terms of modeling of mooring lines and floaters, and more accurate than the catenary equation, and can be used effectively in the early design phase of dimension mooring lengths for moored floating structures. Full article

(This article belongs to the Special Issue Design and Analysis of Offshore Structures)

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20 pages, 27695 KiB

Open AccessArticle

Experimental Investigation on Structural Responses of a Partially Submerged 2D Flat Plate with Hammering and Breaking Waves for Numerical Validation

by Yoon-Jin Ha, Byoung-Jae Park, Yun-Ho Kim and Kang-Su Lee

J. Mar. Sci. Eng. 2021, 9(6), 621; https://doi.org/10.3390/jmse9060621 - 03 Jun 2021

Cited by 2 | Viewed by 1743

Abstract

In this study, experiments were conducted to provide validation data for numerical simulations. Model tests were conducted in a 2D wave flume at the Korea Research Institute of Ships and Ocean Engineering (KRISO). A series of hammering tests for two flat plates with different lengths under dry and partially wet conditions were performed to investigate the vibrating frequencies in each mode. Thereafter, breaking wave tests were performed using the focusing wave method. Repetitive tests were performed five times in each condition. The repetitive test results showed good agreement in each case, and the frequencies for each mode of the two flat plates were numerically calculated. In addition, the wave and air bubble frequencies were captured unlike in the hammering tests. The frequencies for each mode, strain and time interval from the experiments for two flat plates were organized, and the data for validation of the numerical simulation were provided. Full article

(This article belongs to the Special Issue Design and Analysis of Offshore Structures)

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17 pages, 4638 KiB

Open AccessArticle

Design and Automated Optimization of an Internal Turret Mooring System in the Frequency and Time Domain

by Hongrae Park and Sungjun Jung

J. Mar. Sci. Eng. 2021, 9(6), 581; https://doi.org/10.3390/jmse9060581 - 27 May 2021

Cited by 5 | Viewed by 2547

Abstract

A cost-effective mooring system design has been emphasized for traditional offshore industry applications and in the design of floating offshore wind turbines. The industry consensus regarding mooring system design is mainly inhibited by previous project experience. The design of the mooring system also requires a significant number of design cycles. To take aim at these challenges, this paper studies the application of an optimization algorithm to the Floating Production Storage and Offloading (FPSO) mooring system design with an internal turret system at deep-water locations. The goal is to minimize mooring system costs by satisfying constraints, and an objective function is defined as the minimum weight of the mooring system. Anchor loads, a floating body offset and mooring line tensions are defined as constraints. In the process of optimization, the mooring system is analyzed in terms of the frequency domain and time domain, and global and local optimization algorithms are also deployed towards reaching the optimum solution. Three cases are studied with the same initial conditions. The global and local optimization algorithms successfully find a feasible mooring system by reducing the mooring system cost by up to 52%. Full article

(This article belongs to the Special Issue Design and Analysis of Offshore Structures)

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