Marine Structures最新文献

{"title":"Design of a quick-connection device for installing pre-assembled offshore wind turbines","authors":"Behfar Ataei ,&nbsp;Zhengru Ren ,&nbsp;Karl Henning Halse","doi":"10.1016/j.marstruc.2024.103720","DOIUrl":"10.1016/j.marstruc.2024.103720","url":null,"abstract":"<div><div>Higher wind velocities and lower wind shear are two motivations driving the development of floating offshore wind turbines (OWTs). However, such designs suffer from high expenses and complicated installation scenarios. Installation of offshore wind turbines is challenging due to the unpredictable nature of the environment and the technical complexities, especially at offshore sites. Mating of OWT on top of the pre-installed substructure is one of the critical stages of the installation operation. Grouted, welded, and bolted connections are utilized conventionally, but all have shortcomings. Welded and grouted connections suffer from fatigue forces, while a bolted connection requires minimal installation tolerances and sensitivity to impact forces. The design of a quick connection device (QCD) is expected to reduce the installation time, expand the operational weather window, and overcome the limitations of the earlier connection devices.</div><div>The QCD described here comprises conic cross-sections, circular plates, and stiffeners connected to the floating substructure and OWT. This research uses a global model to estimate the relative velocities and displacements between the OWT and spar buoy. Furthermore, a local finite element model is developed to assess the influence of the impact forces and the design of the connection device. Implementing the hydrostatic stiffness of the floating spar within the impact simulations improved the simulation fidelity and reduced the impact damage. Different impact scenarios are performed, and the sensitivity of impact damage concerning the distribution of impact initiation points is assessed. Furthermore, an active control mechanism is used to reduce the relative motions between the installation vessel and the floating substructure. It is concluded that utilizing the anti-swing active control system minimizes the impact velocity and impact damage. This research can be extended by optimizing the design of the quick connection device.</div></div>","PeriodicalId":49879,"journal":{"name":"Marine Structures","volume":"100 ","pages":"Article 103720"},"PeriodicalIF":4.0,"publicationDate":"2024-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142655179","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"An ULS reliability-based design method for mooring lines using an efficient full long-term approach","authors":"Marina Leivas Simão ,&nbsp;Luis Volnei Sudati Sagrilo ,&nbsp;Paulo Maurício Videiro ,&nbsp;Mauro Costa de Oliveira","doi":"10.1016/j.marstruc.2024.103718","DOIUrl":"10.1016/j.marstruc.2024.103718","url":null,"abstract":"<div><div>In the long-term scenario, the environmental actions to which floating offshore structures are subjected to, such as waves, wind and current, are non-stationary stochastic processes. However, this long-term behavior is usually modeled as a series of short-term stationary conditions. In a full long-term analysis approach, an estimate of the N-year response can be obtained through a multi-dimensional integration over expected short-term environmental conditions. An innovative and more efficient long-term integration approach based on the Importance Sampling Monte Carlo Simulation (ISMCS) method is presented, where the uniform distribution over an environmental contour is used as the sampling function. In parallel, a multi-dimensional joint environmental model that statistically describes all relevant environmental parameters is employed, contemplating linear and directional variables, and thoroughly accounting for the occurrences of wind waves and swell. The methodology is applied to two FPSOs systems installed in Brazilian ultradeep waters. Ultimately, a design-oriented procedure based on the developed methodologies is provided, using an Ultimate Limit State (ULS) reliability-based design with calibrated safety factors in an LRFD (Load and Resistance Factors Design) format. It is shown that the developed procedures can be powerful tools to account for the simultaneous occurrence of wind sea and swell waves in offshore system response evaluations required in the design and life extension analyses.</div></div>","PeriodicalId":49879,"journal":{"name":"Marine Structures","volume":"99 ","pages":"Article 103718"},"PeriodicalIF":4.0,"publicationDate":"2024-11-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142661842","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}

{"title":"A probability-based study on failure mechanism and quantitative risk analysis for buried offshore pipelines subjected to third-party impact loads, exploring the effects of spatial variability of soil strength","authors":"Fengyuan Jiang ,&nbsp;Sheng Dong ,&nbsp;Carlos Guedes Soares","doi":"10.1016/j.marstruc.2024.103719","DOIUrl":"10.1016/j.marstruc.2024.103719","url":null,"abstract":"<div><div>Burial is an effective approach to offshore pipeline protection for impact loads. However, few studies address the influences of inherent soil spatial variabilities on failure behaviour of soil covers and pipelines, causing deviations. Therefore, a random field-large deformation finite element analysis framework is developed to explore the failure mechanisms of buried pipelines in spatially varying soils. The failure mode of soil cover is conformed to a local mode, where the failure path is insensitive to soil variability. The failure mechanism of pipelines depends on the competition mechanism between soil strengths and pipe-soil interactions, based on which two typical failure modes are summarized. Soil variability not only aggravates the impact damage but also stimulates the diversity of structural responses. Correlations between probabilistic damage degrees and multiple influential factors are discussed. Further, inspired by the principle of energy dissipation, an integrated quantitative risk assessment model is derived to reveal the failure risk evolution, where uncertainties from soil variabilities and structure-related factors are considered. The latter shows a significant influence, which may pose an additional failure probability of over 50 %. Different safety design approaches are compared, and spatial failure probability surfaces are configured for burial depth determination.</div></div>","PeriodicalId":49879,"journal":{"name":"Marine Structures","volume":"99 ","pages":"Article 103719"},"PeriodicalIF":4.0,"publicationDate":"2024-11-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142661696","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}

{"title":"Elastic mode expansion in smoothed particle hydrodynamics framework for hydroelasticity and validation with 3D hydroelastic wedge impact experiments","authors":"Chaitanya Kesanapalli,&nbsp;HeonYong Kang","doi":"10.1016/j.marstruc.2024.103721","DOIUrl":"10.1016/j.marstruc.2024.103721","url":null,"abstract":"<div><div>To perform an efficient hydroelastic simulation with violent free surface interactions, we extend δ+ SPH to elastic modes of a floating structure through GPU parallelization, which includes the correction of velocity divergence with the deformation and computation of the structure's strain. Free surface interaction is supplemented with a segmented particle shifting and tensile instability correction. We validate the developed hydroelastic simulation for experiments of elastic wedge impacts with aluminum and composite panels. Through comparative analysis with different deadrise angles and impact velocities, we find that the improved free surface interactions reduce early separation from the deforming panels, leading to better prediction of the wedge acceleration and reasonably well-matched profiles of the free surface and panel deformation. The marginal difference is attributable to the water passing through the gaps of the physical test model built in three dimensions, which is absent in the simulation setup. Comparing strain time series, measured at two locations on the elastic panels, through three sets of simulations in different dimensions of the simulation set-up and mode shapes, we see that three-dimensional simulation with correct mode shapes in three dimensions accurately predicts the strain time series at both locations as well as the wedge acceleration. The hydroelastic simulation through the modal expansion in GPU parallelization can be utilized to efficiently predict various hydroelastic phenomena with violent free surface interactions.</div></div>","PeriodicalId":49879,"journal":{"name":"Marine Structures","volume":"99 ","pages":"Article 103721"},"PeriodicalIF":4.0,"publicationDate":"2024-11-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142661840","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}

{"title":"Extreme nonlinear ship response estimations by active learning reliability method and dimensionality reduction for ocean wave","authors":"Tomoki Takami ,&nbsp;Masaru Kitahara ,&nbsp;Jørgen Juncher Jensen ,&nbsp;Sadaoki Matsui","doi":"10.1016/j.marstruc.2024.103723","DOIUrl":"10.1016/j.marstruc.2024.103723","url":null,"abstract":"<div><div>An efficient extreme ship response prediction approach in a given short-term sea state is devised in the paper. The present approach employs an active learning reliability method, named as the active learning Kriging + Markov Chain Monte Carlo (AK-MCMC), to predict the exceedance probability of extreme ship response. Apart from that, the Karhunen-Loève (KL) expansion of stochastic ocean wave is adopted to reduce the number of stochastic variables and to expedite the AK-MCMC computations. Weakly and strongly nonlinear vertical bending moments (VBMs) in a container ship, where the former only accounts for the nonlinearities in the hydrostatic and Froude-Krylov forces, while the latter also accounts for the nonlinearities in the radiation and diffraction forces together with slamming and hydroelastic effects, are studied to demonstrate the efficiency and accuracy of the present approach. The nonlinear strip theory is used for time domain VBM computations. Validation and comparison against the crude Monte Carlo Simulation (MCS) and the First Order Reliability Method (FORM) are made. The present approach demonstrates superior efficiency and accuracy compared to FORM. Moreover, methods for estimating the Mean-out-crossing rate of VBM based on reliability indices derived from the present approach are proposed and are validated against long-time numerical simulations.</div></div>","PeriodicalId":49879,"journal":{"name":"Marine Structures","volume":"99 ","pages":"Article 103723"},"PeriodicalIF":4.0,"publicationDate":"2024-11-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142661841","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}

{"title":"Structural performance at the joint of precast pile-supported pier structure","authors":"Sang Kyu Cho ,&nbsp;Tae Hoon Koo ,&nbsp;Won Chul Cho","doi":"10.1016/j.marstruc.2024.103722","DOIUrl":"10.1016/j.marstruc.2024.103722","url":null,"abstract":"<div><div>Recently, precast construction methods have been increasingly applied to pile-supported pier structures in coastal areas, offering simplified construction processes, shorter construction periods, and minimized environmental pollution. The use of precast members in offshore construction allows for prefabricated assembly, reducing the need for temporary installations and minimizing field casting work. However, pile-supported pier structures in coastal regions are subject to various marine loads, such as wave, berthing, wind forces and live load, along with uplifting forces due to sea-level rise, making it essential to verify the joints—typically the most vulnerable part of precast structures. This study conducts numerical analyses and experimental tests to evaluate the behavior of joints in newly developed precast structures and assess their structural safety. Results indicate that the failure mode of the structure initiates and progresses at the joint where the precast members connect to field-cast sections. Additionally, it was confirmed that failure originates at the weakest point in areas where precast girders, precast pile caps, and piles are interconnected. Nonetheless, the proposed structure demonstrated structural performance that significantly exceeded the design load.</div></div>","PeriodicalId":49879,"journal":{"name":"Marine Structures","volume":"99 ","pages":"Article 103722"},"PeriodicalIF":4.0,"publicationDate":"2024-11-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142661695","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}

{"title":"Development and performance study of a multi-degree-of-freedom loading device for real-time hybrid model testing of floating offshore wind turbines","authors":"Jie Fu ,&nbsp;Wei Shi ,&nbsp;Xu Han ,&nbsp;Madjid Karimirad ,&nbsp;Tao Wang ,&nbsp;Xin Li","doi":"10.1016/j.marstruc.2024.103717","DOIUrl":"10.1016/j.marstruc.2024.103717","url":null,"abstract":"<div><div>To address the challenges encountered in reproducing turbulent wind loads and scaling conflicts between the turbine and platform in traditional model tests for floating offshore wind turbines. This paper proposes a new real-time hybrid model test strategy with a multi-degree-of-freedom loading device. The design theories of the multi-degree-of-freedom loading device are thoroughly presented. Following this, a software-in-the-loop simulation system was constructed in MATLAB to develop simulation validation on the feasibility and load reproduction capability of the multi-degree-of-freedom loading device. This study addresses the challenges of scale conflicts and turbulent wind load reproduction in traditional model tests, providing a reference for the further development of real-time hybrid model testing techniques for floating offshore wind turbine. The results indicate that the thrust force error in the Fx direction is within 2 %, while the torque and bending moment errors in the Mx, My, and Mz directions are within 8 %. Finally, a hardware-in-the-loop testing system was established to conduct performance tests on the static and dynamic load reproduction capabilities of the multi-degree-of-freedom loading device. The dynamic load variation rate of the multi-degree-of-freedom loading device is 45 N/s, ensuring its capability for dynamic force changes at the scaled-down level. The reproducibility of aerodynamic loads on floating offshore wind turbine under steady wind and turbulent wind conditions by the multi-degree-of-freedom loading device is investigated. The maximum error in reproducing steady wind loads using the multi-degree-of-freedom loading device was found to be 3.7 %. In comparison, the maximum error in reproducing the average values of thrust force and torques in different directions under turbulent wind loads was 9.05 %. Within the 0–5 Hz frequency range, the aerodynamic loads in various directions achieved an energy recurrence rate of at least 99.2 %. It has been demonstrated that the thrust force, torque and bending moment of the floating offshore wind turbine can be effectively reproduced by the device, thereby mitigating the impact of scale effects on floating offshore wind turbine model testing.</div></div>","PeriodicalId":49879,"journal":{"name":"Marine Structures","volume":"99 ","pages":"Article 103717"},"PeriodicalIF":4.0,"publicationDate":"2024-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142661688","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}

{"title":"A frequency domain method for fully coupled modelling and dynamic analysis of floating wind turbines","authors":"Peng Chen ,&nbsp;Zhengshun Cheng ,&nbsp;Shi Deng ,&nbsp;Zhiqiang Hu ,&nbsp;Torgeir Moan","doi":"10.1016/j.marstruc.2024.103715","DOIUrl":"10.1016/j.marstruc.2024.103715","url":null,"abstract":"<div><div>In design of Floating Wind Turbines (FWTs), balancing computational efficiency with analytical accuracy is crucial, a challenge often unmet by time-domain methods. This study innovatively develops and verifies an efficient frequency domain method for fully coupled modelling and dynamic analysis of FWTs, termed DARwind-FD. The tower of the FWT is conceptualised as a beam, with the rotor-nacelle assembly (RNA) and the floating platform envisaged as rigid bodies situated at each extremity. The aerodynamic loads are evaluated utilising the Blade Element Momentum (BEM) theory, supplemented with an analytical model accounting for added mass and damping. The hydrodynamic loads are assessed through the Linear Potential Flow theory, taking into account both first and second-order wave forces along with viscous effects. The mooring forces are analysed using a linearised stiffness matrix, derived from a quasi-static catenary methodology. The code-to-code verification of DARwind-FD is based on the OC4 DeepCwind semi-submersible platform with a 5MW wind turbine, aligns well with OpenFAST time-domain results in terms of dynamic responses such as platform motions, mooring tension, tower base bending moment, and nacelle acceleration under various conditions. The outcomes of this research offer robust technical support for the preliminary design and optimisation of FWTs, thereby contributing to the sustainable advancement of offshore wind energy systems.</div></div>","PeriodicalId":49879,"journal":{"name":"Marine Structures","volume":"99 ","pages":"Article 103715"},"PeriodicalIF":4.0,"publicationDate":"2024-11-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142572886","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}

{"title":"Numerical simulation of moored ships in level ice considering dynamic behavior of mooring cable","authors":"Jiaming Chen ,&nbsp;Li Zhou ,&nbsp;Shifeng Ding ,&nbsp;Fang Li","doi":"10.1016/j.marstruc.2024.103716","DOIUrl":"10.1016/j.marstruc.2024.103716","url":null,"abstract":"<div><div>This study develops a new numerical method to simulate the interaction between a moored ship and level ice, taking into account the time-domain effective tension of each mooring cable. Previous studies primarily focused on the ice load exerted on the hull, with an emphasis on accurately predicting of the dynamic ice load. However, for moored structures in polar regions, the mooring system often comes into direct contact with the ice rubble formed during icebreaking process, an interaction that has been largely overlooked in existing studies. The interaction between submerged ice rubble and mooring cables significantly affects both the mooring loads and global motion of the ship. The results show that: 1) When accounting for the ice collision force on the mooring cables, both the total ice force and effective tension on key cables match the experimental data; 2) For different mooring cables, the ice collision force either decreases and increases effective tension depending on the collision angle between the cable and ice rubble; 3) The ice load on the mooring cables play a critical role, significantly impacting both the cables and the entire system. The proposed model is reliable and offers an effective, convenient method for predicting the dynamic response of mooring cables under ice collision forces.</div></div>","PeriodicalId":49879,"journal":{"name":"Marine Structures","volume":"99 ","pages":"Article 103716"},"PeriodicalIF":4.0,"publicationDate":"2024-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142572885","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}

{"title":"Investigation of higher-order springing of a ship in regular waves by experimental analysis and two-way CFD-FEA coupled method","authors":"Binyang Xie ,&nbsp;Sumit Kumar Pal ,&nbsp;Kazuhiro Iijima ,&nbsp;Akira Tatsumi ,&nbsp;Timoteo Badalotti","doi":"10.1016/j.marstruc.2024.103712","DOIUrl":"10.1016/j.marstruc.2024.103712","url":null,"abstract":"<div><div>In this paper, the higher-order springing phenomenon is addressed for a segmented barge ship model through experimental and numerical measures. An efficient in-house two-way coupled numerical solver between Computational Fluid Dynamics (CFD) and Finite Element Analysis (FEA) is developed and validated against experimental results. The coupling method is based on a domain-separated approach and necessitates the resolution of individual boundary value problems in distinct domains. To ensure convergence within these individual domains, an implicit numerical scheme is employed and further facilitated exchange of variables for coupling. The current approach emphasizes the overall convergence between two solvers, maintaining a strongly coupled setup to comprehensively address fluid-structure interaction phenomena, including added mass and damping effects. A series of tank tests were conducted first to measure the wave-induced sectional loads and motions, during which the springing responses to very high-order harmonics of wave load were observed. By comparing the numerical prediction with the tank test results for rigid body motion and flexible vertical bending moment (VBM), the proposed numerical method demonstrated agreement with experimental results, affirming its validity and robustness. Finally, the springing response up to 14th order harmonics is discussed and investigated.</div></div>","PeriodicalId":49879,"journal":{"name":"Marine Structures","volume":"99 ","pages":"Article 103712"},"PeriodicalIF":4.0,"publicationDate":"2024-10-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142561030","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}