Marine StructuresPub Date : 2025-07-03DOI: 10.1016/j.marstruc.2025.103889
Peng Liu , Yonghong Liu , Qingxiang Wang , Xinlei Wu , Chi Ma
{"title":"Study on plasma arc penetration process of abandoned offshore wells","authors":"Peng Liu , Yonghong Liu , Qingxiang Wang , Xinlei Wu , Chi Ma","doi":"10.1016/j.marstruc.2025.103889","DOIUrl":"10.1016/j.marstruc.2025.103889","url":null,"abstract":"<div><div>Recently, massive numbers of offshore production platforms have faced decommissioning. Abandoned offshore wells demolition is a significant part of offshore platform decommissioning. This work explored the plasma arc penetration process of abandoned offshore wells. Three types of workpieces were made for underwater penetration experiments. Workpiece 1 was a single-layer steel plate, workpiece 2 was a double-layer steel plate with a gap, and workpiece 3 was a double-layer steel plate with a cement layer. It was found that slag bridging occurred during the penetration of workpiece 2. Slag bridging was closely related to the gap size. There was no slag bridging during the penetration of workpiece 3, but its penetration difficulty was the greatest among the three working conditions. It was also found that the penetration effect of the second steel plate was strongly influenced by the branching arc acting on the second steel plate. The wider the gap and the cement layer, the lower the branching arc current on the second steel plate and the worse the penetration effect. In summary, the plasma arc can penetrate all three types of workpieces under certain operating conditions. This technology is expected to play a significant role in abandoned offshore wells demolition.</div></div>","PeriodicalId":49879,"journal":{"name":"Marine Structures","volume":"104 ","pages":"Article 103889"},"PeriodicalIF":4.0,"publicationDate":"2025-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144549588","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Marine StructuresPub Date : 2025-07-03DOI: 10.1016/j.marstruc.2025.103892
Shamsher Sadiq , Hyeon-Jung Kim , Myoung-Soo Won , Young-Chul Park
{"title":"A qualitative study on the lateral behavior of rock-socketed monopiles","authors":"Shamsher Sadiq , Hyeon-Jung Kim , Myoung-Soo Won , Young-Chul Park","doi":"10.1016/j.marstruc.2025.103892","DOIUrl":"10.1016/j.marstruc.2025.103892","url":null,"abstract":"<div><div>Monopile supporting offshore wind turbines (OWT) in regions with shallow rock can benefit from rock-socketing. This study qualitatively investigates the effect of the rock layer on the serviceability limit state (SLS) and the ultimate limit state (ULS) of the monopiles. A nonlinear three-dimensional finite element model was constructed to simulate monopile–soil interaction and was validated using data from centrifuge experiments. The effect of the rock-socketing was analyzed for three cases flexible, semi-rigid and rigid, and compared with conditions in pure sand. The results are presented in terms of the limit state selection, lateral capacities, lateral deformation modes, soil deformation patterns, lateral earth pressure distribution and soil reaction curves (p-y). The finding indicates that rock-socketing significantly affects the lateral responses for semi-rigid and rigid monopiles, while its impact on the flexible monopiles is minimal. Furthermore, the study highlights the need to develop a generalized lateral earth pressure distribution for the simplified lateral response prediction of rock-socketed monopiles.</div></div>","PeriodicalId":49879,"journal":{"name":"Marine Structures","volume":"104 ","pages":"Article 103892"},"PeriodicalIF":4.0,"publicationDate":"2025-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144535537","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Marine StructuresPub Date : 2025-07-03DOI: 10.1016/j.marstruc.2025.103887
Yongqiang Chen , Xiantao Zhang , Xiaodong Wu
{"title":"Eliciting dynamic features of a large interconnected box-pontoon-type offshore floating photovoltaic array","authors":"Yongqiang Chen , Xiantao Zhang , Xiaodong Wu","doi":"10.1016/j.marstruc.2025.103887","DOIUrl":"10.1016/j.marstruc.2025.103887","url":null,"abstract":"<div><div>This paper investigates a 5MW box-pontoon-type interconnected Offshore Floating Photovoltaic (OFPV) square platform with a side length of 160 m. Two primary problems in designing the box-pontoon-type OFPV platform are addressed, that is, the optimal modular unit size (hinge configurations) within specific wavelength range, and under what conditions can the structure be treated rigid to mitigate computational cost. To deal with the first issue, the displacement type is proposed after investigations into hydroelasticity of fifteen hinge configurations. The selected hinge configurations should put the structure in proper displacement type with relatively small vertical displacement and mild hinge shear force. To deal with the latter issue, dynamic responses of rigid modular units are calculated and compared, which indicate the box-pontoon-type OFPV cannot be simplified as rigid bodies unless it has an unrealistic large elastic modulus. The genralized rigid state is then proposed to illustrate a critical elastic modulus value, which shows that hydroelasticity will stablize instead of increasing once the structure’s elastic modulus exceeds this value.</div></div>","PeriodicalId":49879,"journal":{"name":"Marine Structures","volume":"104 ","pages":"Article 103887"},"PeriodicalIF":4.0,"publicationDate":"2025-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144535538","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Marine StructuresPub Date : 2025-07-03DOI: 10.1016/j.marstruc.2025.103879
Jorrid Lund, Lina Sapp, Jan Manuel Kubiczek, Angelo Mario Böhm, Franz von Bock und Polach
{"title":"Simulated ice loads on a ship propeller and comparison with full-scale measurements","authors":"Jorrid Lund, Lina Sapp, Jan Manuel Kubiczek, Angelo Mario Böhm, Franz von Bock und Polach","doi":"10.1016/j.marstruc.2025.103879","DOIUrl":"10.1016/j.marstruc.2025.103879","url":null,"abstract":"<div><div>A methodology to better estimate the loads of ice acting on the propeller of a ship is developed. Based on measurements conducted in the North Pole region, an existing failure model for ice based on the Mohr–Coulomb nodal split approach is modified to better represent the lower strength of polar ice compared to laboratory ice. The modified material model for the sea ice is used to compute the propeller torque and a load spectrum for the propeller-ice interaction of the research ship <em>S.A. Agulhas II</em>. To this end, a floe-ice breaking simulation is used to estimate the size and shape of the ice cusps hitting the propeller of this ship. In the next step, a set of finite element simulations of the propeller-ice interaction utilizing the modified Mohr–Coulomb nodal split model is conducted. Based on this, the load spectrum is computed and compared with the measured torque on the propeller shaft of the <em>S.A. Agulhas II</em>. The successful reproduction shows the applicability of the approach to better estimate the loads exerted by the ice on the propeller.</div></div>","PeriodicalId":49879,"journal":{"name":"Marine Structures","volume":"104 ","pages":"Article 103879"},"PeriodicalIF":4.0,"publicationDate":"2025-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144549587","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Marine StructuresPub Date : 2025-07-01DOI: 10.1016/j.marstruc.2025.103883
Bruno A. Roccia , Thi-Hoa Nguyen , Petter Veseth , Finn Gunnar Nielsen , Cristian G. Gebhardt
{"title":"On the use of an advanced Kirchhoff rod model to study mooring lines","authors":"Bruno A. Roccia , Thi-Hoa Nguyen , Petter Veseth , Finn Gunnar Nielsen , Cristian G. Gebhardt","doi":"10.1016/j.marstruc.2025.103883","DOIUrl":"10.1016/j.marstruc.2025.103883","url":null,"abstract":"<div><div>In this work, we investigate the application of an advanced nonlinear torsion- and shear-free Kirchhoff rod model, enhanced with a penalty-based barrier function (to simulate the seabed contact), intended for studying the static and dynamic behavior of mooring lines. The formulation incorporates conservative and non-conservative external loads, including those coming from the surrounding flow (added mass, tangential drag, and normal drag). To illustrate the favorable features of this model, we consider some key scenarios such as static configurations, pulsating force applications at the fairlead, and fluid–structure interaction between mooring lines and the surrounding flow. Verification against well-established solutions, including catenary configurations and OpenFAST simulations, shows excellent accuracy in predicting mooring line responses for a floating offshore wind turbine. Among the most important results, we can mention that under normal pulsating loads at the fairlead, the mooring line exhibits a transition from a drag-dominated regime at low frequencies to an added-mass-dominated regime at higher frequencies. Furthermore, tangential forcing at the fairlead reveals a strong coupling between axial and bending dynamics, contrasting with normal forcing scenarios where axial dynamics remain largely unaffected. These findings underscore the potential of the proposed approach for advanced mooring line simulations.</div></div>","PeriodicalId":49879,"journal":{"name":"Marine Structures","volume":"104 ","pages":"Article 103883"},"PeriodicalIF":4.0,"publicationDate":"2025-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144523787","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Marine StructuresPub Date : 2025-07-01DOI: 10.1016/j.marstruc.2025.103891
Puyang Zhang, Yabo Pang, Xin Qi, Conghuan Le, Hongyan Ding
{"title":"Penetration installation of the13-compartment mono-column composite bucket foundation for offshore wind turbines","authors":"Puyang Zhang, Yabo Pang, Xin Qi, Conghuan Le, Hongyan Ding","doi":"10.1016/j.marstruc.2025.103891","DOIUrl":"10.1016/j.marstruc.2025.103891","url":null,"abstract":"<div><div>The 13-compartment mono-column composite bucket foundation, which will be abbreviated as \"The 13-compartment MCCBF\" in the following text, has stronger applicability to the shallow bedrocks and plays an important role in the development of wind farms in the South China Sea with more shallow bedrocks. This paper studies the penetration installation characteristics of 13-compartment MCCBF under four geological conditions: pure sand, clay over sand, sand over shallow bedrock, and clay over shallow bedrock. Through a 1:60 scale model test, the variation law of the pore water pressure around the foundation during its penetration installation was analyzed, the morphological changes of the surrounding soil and the development law of soil plug after the foundation installation were explained, and the required penetration suction of the foundation under different geological conditions was explored. The research results show that during the penetration installation of the foundation, the required pressure difference increases with the increase of the penetration depth, the pressure of the compartment in the overlying clay geology is higher than that in the overlying sand geology, with a difference of about 3–5.5 times. The penetration installation speed of the foundation in the shallow bedrock geology is faster, about 1.6–5 times that of the geology without shallow bedrocks. The volume of seepage water in the sand over shallow bedrock geology is about 50 % of that in the pure sand geology. Soil plug will be formed in the process of foundation penetration, among which the soil plug is the highest in the sand over shallow bedrock geology.</div></div>","PeriodicalId":49879,"journal":{"name":"Marine Structures","volume":"104 ","pages":"Article 103891"},"PeriodicalIF":4.0,"publicationDate":"2025-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144523788","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Marine StructuresPub Date : 2025-06-30DOI: 10.1016/j.marstruc.2025.103884
Zijian Jin, Hui Fang, Yong Liu
{"title":"Numerical investigation on hydro-elastoplastic responses of floating laminated structures under wave action","authors":"Zijian Jin, Hui Fang, Yong Liu","doi":"10.1016/j.marstruc.2025.103884","DOIUrl":"10.1016/j.marstruc.2025.103884","url":null,"abstract":"<div><div>Based on the Coupled Eulerian-Lagrangian (CEL) numerical method in Finite Element Modelling (FEM) software ABAQUS, a numerical wave flume model was established to solve the wave-structural elastoplastic coupling problem of floating laminated structures. The physical wave-generating mode was adopted to form waves by controlling the motion of a rigid plate, and the water wave dissipation was realized by establishing a damping zone with high dynamic viscosity coefficients. A two-way fluid-structure coupling numerical approach was further proposed and verified for the hydro-elastoplastic problem of floating structures. The present two-way interaction approach was validated based on the previous physical test for the floating homogenous structures and the theoretical model for the floating laminated structures. Finally, combining the composite material configuration, reinforced member characteristic, structural laminated feature, and hydrodynamic loads, a multiscale numerical framework with the CEL-FEM approach was presented to intuitively simulate the hydro-elastoplastic responses of the floating laminated structures under wave action. As an illustration, a floating laminated structure (FLS) was initially designed to consist of the lower deformable layer and the upper high-stiffness reinforced layer. Based on the multiscale numerical framework, the initial design of FLS was optimized by ameliorating the material meso-composition and reinforced member macro-parameter to realize the structural performance enhancement. Fully simulating the interactive processes between water waves and structural elastoplasticity of the FLSs under different wave conditions, the mechanism and understanding of the hydro-elastoplastic problem was elucidated by analyzing the evolutions of the hydrodynamic characteristics, plastic dissipation energy, fluid domain stress distribution, and structural responses.</div></div>","PeriodicalId":49879,"journal":{"name":"Marine Structures","volume":"104 ","pages":"Article 103884"},"PeriodicalIF":4.0,"publicationDate":"2025-06-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144517356","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Marine StructuresPub Date : 2025-06-30DOI: 10.1016/j.marstruc.2025.103890
Katavut Vichai , Duy Tan Tran , Jim Shiau , Suraparb Keawsawasvong , Pitthaya Jamsawang
{"title":"Predicting failure envelopes of skirted spudcan footings under combined loads using ACOoptimized extremely randomized trees","authors":"Katavut Vichai , Duy Tan Tran , Jim Shiau , Suraparb Keawsawasvong , Pitthaya Jamsawang","doi":"10.1016/j.marstruc.2025.103890","DOIUrl":"10.1016/j.marstruc.2025.103890","url":null,"abstract":"<div><div>Skirted spudcan foundations are widely employed in offshore geotechnical engineering due to their enhanced penetration capability and superior load resistance in soft clay soils. In this study, the undrained failure envelope of skirted spudcan subjected to combined vertical, horizontal, and moment (VHM) loading is investigated using Finite Element Limit Analysis (FELA). A total of 624 simulations are performed in OptumG3, systematically varying the embedment ratio (<em>L/D</em>), soil strength heterogeneity (<em>κ</em>), vertical load mobilization (<em>V/V<sub>0</sub></em>), and loading limit for the FELA (<em>β</em>) to construct the VHM failure envelope in non-homogeneous clay. To complement the numerical approach and mitigate computational intensity, a machine learning model is developed using Extremely Randomized Trees (ET) optimized via Ant Colony Optimization (ACO). The resulting ET-ACO model demonstrates excellent agreement with the FELA outcomes, achieving R² values exceeding 0.998. Feature importance analysis highlights the FELA loading limit (<em>β</em>) and embedment ratio (<em>L/D</em>) as the most influential parameters governing failure capacity. This data-driven methodology provides a reliable and effective alternative for evaluating offshore foundation performance, as it not only accelerates the prediction of failure envelopes but also significantly reduces computational costs.</div></div>","PeriodicalId":49879,"journal":{"name":"Marine Structures","volume":"104 ","pages":"Article 103890"},"PeriodicalIF":4.0,"publicationDate":"2025-06-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144518687","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Marine StructuresPub Date : 2025-06-27DOI: 10.1016/j.marstruc.2025.103888
Wei Shi , Jie Fu , Lingyang Cao , Xu Han , Ling Wan , Madjid Karimirad , Wenhua Wang
{"title":"Multi-rotor-based real-time hybrid model tank testing of a 10-MW semi-submersible offshore floating wind turbine","authors":"Wei Shi , Jie Fu , Lingyang Cao , Xu Han , Ling Wan , Madjid Karimirad , Wenhua Wang","doi":"10.1016/j.marstruc.2025.103888","DOIUrl":"10.1016/j.marstruc.2025.103888","url":null,"abstract":"<div><div>Traditional model test faces challenges such as scale effects, difficulties in reproducing turbulent wind, and the inability to simulate shutdown conditions. To address these issues, a 10 MW semi-submersible offshore floating wind turbine was selected as the research subject. An innovative real-time hybrid model test based on a multi-rotor loading device is proposed. The development process of the numerical substructure, the design and control of the loading device has been made public. The physical substructure was designed at a 1:75 scale and installed in a wave tank, where free decay, regular wave, only wind, combined wind and irregular wave, and shutdown tests were conducted. Experimental data were compared and analyzed against simulation results. In the wind test results, the maximum deviation in the mean aerodynamic load across different directions was only 2.59%, indicating that the developed multi-degree-of-freedom loading device effectively reproduces turbulent wind loads. In the two repeated combined wind-wave tests, the average errors for platform surge, pitch, heave motions, and mooring tension were found to be within 2.12%, indicating that repeatability is exhibited by the developed hybrid model test technology. The hybrid experimental method developed in this study simulates the shutdown operating conditions of offshore wind turbines, the study reveals that under parked conditions, the proportion of wave frequency in the platform motion response power spectrum increases significantly. The motion response of offshore wind turbines, induced by impact loads during shutdown, provides valuable insights for the design of offshore wind turbines.</div></div>","PeriodicalId":49879,"journal":{"name":"Marine Structures","volume":"104 ","pages":"Article 103888"},"PeriodicalIF":4.0,"publicationDate":"2025-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144491622","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Marine StructuresPub Date : 2025-06-27DOI: 10.1016/j.marstruc.2025.103886
Jun Yan , Yufeng Bu , Ruonan Zhou , Lizhe Jiang , Chunyu Zhao , Yuanchao Yin
{"title":"Optimization design of helical carcass supported flexible cryogenic pipe based on BP-MOWOA","authors":"Jun Yan , Yufeng Bu , Ruonan Zhou , Lizhe Jiang , Chunyu Zhao , Yuanchao Yin","doi":"10.1016/j.marstruc.2025.103886","DOIUrl":"10.1016/j.marstruc.2025.103886","url":null,"abstract":"<div><div>In recent years, the demand for offshore liquefied natural gas (LNG) exploration and transportation has set higher performance standards for cryogenic pipes, particularly the helical carcass supported flexible cryogenic pipe (hc-FCP). Due to its multi-layered, spiral-wound, and non-bonded structure, optimizing the design of hc-FCP presents significant challenges. This paper proposes an optimization approach combining the backpropagation neural network and the multi-objective whale optimization algorithm (BP-MOWOA) to address the multi-objective optimization of hc-FCP structures. First, a high-precision finite element model of the hc-FCP was established and validated through experimental data. The model was used to generate a large dataset that captured the mechanical performance of hc-FCP under various operating conditions. Second, a backpropagation (BP) neural network was trained to predict the axial tensile and bending stiffness of the hc-FCP, forming the basis for the optimization process. Lastly, the BP-MOWOA was employed to optimize critical design parameters, such as the winding angles of the reinforcement layers, to achieve maximum axial tensile stiffness and reduced bending stiffness with minimal material consumption. The optimized design improved axial tensile stiffness by 24.35 %, reduced bending stiffness by 2.99 %, and lowered material consumption by 1.84 %. These results demonstrate the effectiveness of the BP-MOWOA in optimizing hc-FCP structures for enhanced performance and cost-efficiency, providing a flexible solution for engineering applications in varying operational conditions.</div></div>","PeriodicalId":49879,"journal":{"name":"Marine Structures","volume":"104 ","pages":"Article 103886"},"PeriodicalIF":4.0,"publicationDate":"2025-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144492065","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}