Sustainable Marine Structures

Journal Information
EISSN : 2661-3158
Published by: Nan Yang Academy of Sciences Pte Ltd (10.36956)
Total articles ≅ 39
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Ruyan Yang, Xiangyuan Zheng, Jinlu Chen, Yufei Wu
Sustainable Marine Structures, Volume 4; https://doi.org/10.36956/sms.v4i2.617

Abstract:
With the increasing demand of energy and the limitation of bottom-fixed wind turbines in moderate and deep waters, floating offshore wind turbines are doomed to be the right technical choice and they are bound to enter a new era of rapid development. The mooring system is a vital system of a floating wind turbine for station-keeping under harsh environmental conditions. In terms of existing floating wind turbine projects, this paper is devoted to discussing the current status of mooring systems and mooring equipment. This paper also presents the mooring analysis methods and points out the technical difficulties and challenges in mooring design, installation, operation and maintenance stages. Finally, the developing trends of the mooring system are summarized, aiming to provide a reference for future mooring research.
Chandrasekaran Srinivasan
Sustainable Marine Structures, Volume 4, pp 55-56; https://doi.org/10.36956/sms.v4i2.669

Abstract:
Marine Structures under Special Loads
Adham M. Amer, Lin Li, Xinying Zhu
Sustainable Marine Structures, Volume 4; https://doi.org/10.36956/sms.v4i2.596

Abstract:
Subsea templates are steel structures used to support subsea well components. Normally, offshore crane vessels are employed to install them to the target location on the seabed. Crossing the splash-zone during the lowering of a subsea template is considered the most critical phase during the installation due to slamming loads and needs to be studied to provide the operational weather criterion during the planning phase. In this study, dynamic response analysis has been carried out to evaluate the allowable sea states for the plash-zone crossing phase of the subsea templates. The numerical model of the lifting system, including the crane vessel and the subsea template, is firstly built in the state-of-the-art numerical program SIMA-SIMO. Then, dynamic analysis with time-domain simulations is carried out for the lifting system under various sea states. The disturbed wave field due to the shielding effects from the installation vessel is considered when calculating the hydrodynamic forces on the template. Statistical modelling of the dynamic responses from different wave realizations is used to estimate the extreme responses of various sea states. The application of the generalized extreme value distribution and Gumbel distribution in fitting the extreme responses is discussed. Moreover, the influence of the shielding effects from the vessel, as well as the influence of the changing size of the suction anchor on the hydrodynamic responses and the allowable sea states are studied.
Selda Oterkus, Bingquan Wang, Erkan Oterkus, , Margot Cocard, Stefanos Stefanos, Jami Buckley, Callum McCullough, Dhruv Boruah, Bob Gilchrist
Sustainable Marine Structures, Volume 4, pp 11-17; https://doi.org/10.36956/sms.v4i2.505

Abstract:
Unlike traditional transportation, container transportation is a relatively new logistics transportation mode. Shipping containers lost at sea have raised safety concerns. In this study, finite element analysis of containers subjected to hydrostatic pressure, using commercial software ANSYS APDL was performed. A computer model that can reasonably predict the state of an ISO cargo shipping container was developed. The von Mises stress distribution of the container was determined and the yield strengthwas adopted as the failure criterion. Numerical investigations showed that the conventional ship container cannot withstand hydrostatic pressure in deep water conditions. A strengthened container option was considered for the container to retain its structural integrity in water conditions.
Chungkuk Jin
Sustainable Marine Structures, Volume 4; https://doi.org/10.36956/sms.v4i2.492

Abstract:
This study investigates the hydro-elastic behaviors of fully submerged horizontal cylinders in different regular waves. Two methods were proposed and compared in this study. The first method was based on potential theory in frequency domain and the discrete-module-beam (DMB) method, which discretizes a floating elastic structure into a sufficient number of rigid bodies while simultaneously representing the elastic behavior from beam elements with Euler-Bernoulli beam and Saint-Venant torsion. Moreover, the Morison method in time domain was employed; this method estimates wave forces from the semi-empirical Morison equation, and the elastic behavior is embodied by massless axial, bending, and torsional springs.Various parametric studies on cylinder diameter, submergence depth, and wave direction were conducted. Wave forces, dry/wet mode shapes/natural frequencies, and dynamic motions are presented and analyzed.
Liang-Cheng Liu, Ge Wang, Jun-Yi Song, Bi-Ru Hu
Sustainable Marine Structures, Volume 4, pp 29-34; https://doi.org/10.36956/sms.v4i1.438

Abstract:
Resolving the contradiction between Marine economic development and Marine ecological environment protection has become an unavoidable and sharp problem. The uncontrolled use of Marine antifouling technology will bring uncontrollable and even irreversible damage to the Marine biosphere, which will lead to ecological disaster and threaten the survival of human beings. Therefore, it is an urgent task to find antifouling technology with lower environmental toxicity under the premise of considering economy. More attention should be paid to the long-term impact of mature and new technologies on the Marine ecological environment. This paper introduces the development status of antifouling technology, its influence on Marine ecological environment and puts forward the design strategy of comprehensive biological fouling prevention and control technology.
Erkan Oterkus, Sangchan Jo
Sustainable Marine Structures, Volume 4, pp 16-28; https://doi.org/10.36956/sms.v4i1.476

Abstract:
In offshore structures, hydrocarbon fires cause the structure to loose its rigidity rapidly and this leads to structural integrity and stability problems. The Passive Fire Protection (PFP) system slows the transfer rate of fire heat and helps to prevent the collapse of structures and human losses. The vital design factors are decided in the detailed design stage. The determined design thickness must be accurately applied in the fabrication yard. However, there are many cases that the PFP is overused because of various reasons. This excessive application of the PFP is an unavoidable problem. Several studies have been conducted on the efficient application and optimal design of the PFP. However, the strength of the PFP has not been considered. In addition, research studies on the correlation between the thickness of the PFP and the structural behaviour are not widely available. Therefore, this study attempts to analyse the thermal and mechanical effects of the PFP on the structure when it is applied to the structural member. In particular, it is intended to determine the change in the behaviour of the structural member as the thickness of the PFP increases.
Srinivasan Chandrasekaran, Hari S
Sustainable Marine Structures, Volume 4, pp 35-41; https://doi.org/10.36956/sms.v4i1.490

Abstract:
Marine structures are exposed to harsh weather conditions, demanding special pre-requisites in design and functional perspectives. Under dynamic loads of larger magnitude, the material-centric design procedure alone is not feasible to ensure the safe disbursement of loads. The compliant offshore structures resist loads primarily by their geometric novelty, and hence their design is form-dominant and no more strength (material) dominant. Large displacements in the rigid body modes in the horizontal plane under lateral loads require their construction material to possess enough ductility to absorb this energy. Steel is one of the most competitive materials for marine structures as it offers good ductility, but corrosion in the marine environment is a major concern. It undergoes strength and functional degradations and therefore requires serious investigation. In the present study, functionally graded material (FGM) is proposed to substitute for steel in marine applications. The method of fabricating FGM and assessing its mechanical and durability properties are discussed. Results show that FGM possesses strength and durability properties at par with the conventionally used X52 steel for marine risers. The presented study will be a major initiative towards future research in exploring competent materials which will be strong and sustainable in the marine environment.
Erkan Oterkus
Sustainable Marine Structures, Volume 4, pp 13-15; https://doi.org/10.36956/sms.v4i1.475

Abstract:
Marine environment is a harsh and challenging environment for both operators and analysers due to extreme weather conditions. As a result of these conditions, marine structures are subjected to extreme and/or cyclic loadings. This will then lead to various different damage modes including corrosion and fatigue. Such damage modes are major threats to the reliability and integrity of marine structures which can cause risk on human and environmental safety, and yield financial losses. Moreover, climate change is a major concern which requires urgent attention. In order to minimize the negative effects of climate change, energy transition from utilisation of fossil fuels to greener energy solutions, such as offshore wind, should be adapted. There is currently a rapid progress on investment on green technologies especially offshore wind energy generation. Another emerging area is hydrogen which is considered as the environmentally friendly fuel of the future.
Zhang ChunLing, Zhang Meng-Li, Wang Zhen-Feng, Hu Song, Wang Dan-Yang, Yang Sheng-Long
Sustainable Marine Structures, Volume 4, pp 1-12; https://doi.org/10.36956/sms.v4i1.474

Abstract:
Argo has become an important constituent of the global ocean observation system. However, due to the lack of sea surface measurements from most Argo profiles, the application of Argo data is still limited. In this study, a thermocline model was constructed based on three key thermocline parameters, i.e, thermocline upper depth, the thermocline bottom depth, and thermocline temperature gradient. Following the model, we estimated the sea surface temperature of Argo profiles by providing the relationship between sea surface and subsurface temperature. We tested the effectiveness of our proposed model using statistical analysis and by comparing the sea surface temperature with the results obtained from traditional methods and in situ observations in the Pacific Ocean. The root mean square errors of results obtained from thermocline model were found to be significantly reduced compared to the extrapolation results and satellite retrieved temperature results. The correlation coefficient between the estimation result and in situ observation was 0.967. Argo surface temperature, estimated by the thermocline model, has been theoretically proved to be reliable. Thus, our model generates theoretically feasible data present the mesoscale phenomenon in more detail. Overall, this study compensates for the lack surface observation of Argo, and provides a new tool to establish complete Argo data sets.
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