The wake of wind turbines is a main concern for offshore wind farms, in which the wake width is a key index and needs to be accurately predicted. However, the existing wake width models have shortcomings in predicting the wake of wind turbines in different offshore environments. In view of this, large eddy simulation (LES) is adopted to simulate offshore wind turbines under various environmental conditions. The analyses show that there are evident differences in wake widths between horizontal and vertical directions. The variations of turbulence intensity and wind speed in the environment have significant effects on the wake width. By fitting the simulation results, a three-dimensional (3-D) wake width model is proposed to predict the wake widths in horizontal and vertical directions, which considers the effects of lateral and vertical turbulence intensities on the wake width in different directions, and uses the thrust coefficient to reflect the effect of wind speed. The proposed 3-D model is then compared with existing models through test cases, indicating that it is more accurate in predicting wake widths in horizontal and vertical directions under different environmental conditions, meanwhile shows good applicability in complex offshore environments.
{"title":"Investigation of three-dimensional wake width for offshore wind turbines under complex environmental conditions by large eddy simulation","authors":"Haixiao Liu, Mingqiu Liu, Zhichang Liang","doi":"10.1115/1.4065867","DOIUrl":"https://doi.org/10.1115/1.4065867","url":null,"abstract":"\u0000 The wake of wind turbines is a main concern for offshore wind farms, in which the wake width is a key index and needs to be accurately predicted. However, the existing wake width models have shortcomings in predicting the wake of wind turbines in different offshore environments. In view of this, large eddy simulation (LES) is adopted to simulate offshore wind turbines under various environmental conditions. The analyses show that there are evident differences in wake widths between horizontal and vertical directions. The variations of turbulence intensity and wind speed in the environment have significant effects on the wake width. By fitting the simulation results, a three-dimensional (3-D) wake width model is proposed to predict the wake widths in horizontal and vertical directions, which considers the effects of lateral and vertical turbulence intensities on the wake width in different directions, and uses the thrust coefficient to reflect the effect of wind speed. The proposed 3-D model is then compared with existing models through test cases, indicating that it is more accurate in predicting wake widths in horizontal and vertical directions under different environmental conditions, meanwhile shows good applicability in complex offshore environments.","PeriodicalId":509714,"journal":{"name":"Journal of Offshore Mechanics and Arctic Engineering","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-07-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141686084","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Ocean current forecasting is essential for tidal renewable energy generation and operation. However, comprehensive studies and an efficient approach for forecasting the current direction at multiple points along the water depth are still lacking. In this study, a data-driven approach was developed to attain short-term prediction in the current direction with reasonable uncertainty quantification. The developed approach employed empirical mode decomposition (EMD) and the warped Gaussian process (WGP) in the forecasting process. The ocean current data were measured by a seabed-mounted acoustic Doppler current profiler (ADCP) in the Haitian Strait and were used to illustrate the developed approach. The measured current direction data were preprocessed with the average shifting method to obtain the principal and random components for the improvement of the forecasting accuracy. The random components were decomposed into intrinsic mode functions (IMFs) and residuals. The principal components, IMFs and residuals of the current direction were then forecasted by the WGP approach. The forecasting performance of the developed approach was investigated through comparisons with those of single standard GP, single WGP and EMD+GP models. The effects of the kernel function and training input on the forecasting efficiency and precision were investigated. The extrapolation performances of the proposed model for a 1-step predication and multistep ahead prediction were also examined.
{"title":"A Data-driven Approach for Forecasting Current Direction with a Hybrid Model of Empirical Mode Decomposition and Warped Gaussian Process","authors":"Xiang Liao, Kai Wei, Qingshan Yang","doi":"10.1115/1.4065876","DOIUrl":"https://doi.org/10.1115/1.4065876","url":null,"abstract":"\u0000 Ocean current forecasting is essential for tidal renewable energy generation and operation. However, comprehensive studies and an efficient approach for forecasting the current direction at multiple points along the water depth are still lacking. In this study, a data-driven approach was developed to attain short-term prediction in the current direction with reasonable uncertainty quantification. The developed approach employed empirical mode decomposition (EMD) and the warped Gaussian process (WGP) in the forecasting process. The ocean current data were measured by a seabed-mounted acoustic Doppler current profiler (ADCP) in the Haitian Strait and were used to illustrate the developed approach. The measured current direction data were preprocessed with the average shifting method to obtain the principal and random components for the improvement of the forecasting accuracy. The random components were decomposed into intrinsic mode functions (IMFs) and residuals. The principal components, IMFs and residuals of the current direction were then forecasted by the WGP approach. The forecasting performance of the developed approach was investigated through comparisons with those of single standard GP, single WGP and EMD+GP models. The effects of the kernel function and training input on the forecasting efficiency and precision were investigated. The extrapolation performances of the proposed model for a 1-step predication and multistep ahead prediction were also examined.","PeriodicalId":509714,"journal":{"name":"Journal of Offshore Mechanics and Arctic Engineering","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-07-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141684123","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Mingda Zhu, Peihua Han, Weiwei Tian, R. Skulstad, Houxiang Zhang, Guoyuan Li
Multi-agent modeling is a challenging issue in intelligent systems, which is further compounded by heavy and complex traffic in maritime contexts. Trajectory forecasting can enhance operation safety. Nonetheless, effectively modeling interactions among vessels poses a significant difficulty. Towards this end, we propose a conditional variational autoencoder approach to ship trajectory prediction in a dynamic and multi-modal encounter situation. Leveraging a shared Recurrent Neural Network architecture and attention mechanism, our method aggregates vessel trajectory data, enabling the model to learn and encapsulate meaningful encounter information across active vessels. We utilize Automatic Identification System data from the Oslofjord region to validate our approach. Through comprehensive experiments conducted on a four-ship encounter dataset, our proposed model demonstrates promising performance, by outperforming the benchmark models. Furthermore, we analyze the prediction model in a wide array of dimensions, showcasing its proficiency in complex ship behaviours learning, modeling ship interaction and approximating actual trajectories.
{"title":"A Deep Generative Model for Multi-Ship Trajectory Forecasting with Interaction Modelling","authors":"Mingda Zhu, Peihua Han, Weiwei Tian, R. Skulstad, Houxiang Zhang, Guoyuan Li","doi":"10.1115/1.4065866","DOIUrl":"https://doi.org/10.1115/1.4065866","url":null,"abstract":"\u0000 Multi-agent modeling is a challenging issue in intelligent systems, which is further compounded by heavy and complex traffic in maritime contexts. Trajectory forecasting can enhance operation safety. Nonetheless, effectively modeling interactions among vessels poses a significant difficulty. Towards this end, we propose a conditional variational autoencoder approach to ship trajectory prediction in a dynamic and multi-modal encounter situation. Leveraging a shared Recurrent Neural Network architecture and attention mechanism, our method aggregates vessel trajectory data, enabling the model to learn and encapsulate meaningful encounter information across active vessels. We utilize Automatic Identification System data from the Oslofjord region to validate our approach. Through comprehensive experiments conducted on a four-ship encounter dataset, our proposed model demonstrates promising performance, by outperforming the benchmark models. Furthermore, we analyze the prediction model in a wide array of dimensions, showcasing its proficiency in complex ship behaviours learning, modeling ship interaction and approximating actual trajectories.","PeriodicalId":509714,"journal":{"name":"Journal of Offshore Mechanics and Arctic Engineering","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141689320","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Felliphe Goes Fernandes Barbosa, Gabriel Gonzalez, Luis V. S. Sagrilo
The design phase of offshore installation projects is supported by numerical simulations. These analyses aims to evaluate the mechanical behavior of the equipment involved, such as vessels and flexible pipes, during that operation. Therefore, a common approach is to take the ocean wave loads modeled as deterministic ones (or regular wave approach), which is a simplification that, on the one hand, allows low computational cost; but, on the other one, lacks the representation of the actual behavior of the wave loads, usually better represented by means of an irregular wave modelling. On the way of searching for an irregular wave analysis procedure to be used in the daily design of lazy-wave riser installation analyses, this work proposes an Artificial Neural Network (ANN)-based approach. The proposed model aims to achieve it by training a convolutional neural network (CNN) fed by generated data from short length finite element-based numerical simulations. This surrogate model can predict quite well the pipe's top tension and approximately the axial tension in the touchdown zone (TDZ) for different configuration stages during the riser's installation operation. Moreover, the proposed model works for different environmental scenarios, which boosts the computational simulation time reduction in this phase of riser design.
{"title":"Using Convolutional Neural Networks in Installation Analysis of Lazy-wave Flexible Risers","authors":"Felliphe Goes Fernandes Barbosa, Gabriel Gonzalez, Luis V. S. Sagrilo","doi":"10.1115/1.4065708","DOIUrl":"https://doi.org/10.1115/1.4065708","url":null,"abstract":"\u0000 The design phase of offshore installation projects is supported by numerical simulations. These analyses aims to evaluate the mechanical behavior of the equipment involved, such as vessels and flexible pipes, during that operation. Therefore, a common approach is to take the ocean wave loads modeled as deterministic ones (or regular wave approach), which is a simplification that, on the one hand, allows low computational cost; but, on the other one, lacks the representation of the actual behavior of the wave loads, usually better represented by means of an irregular wave modelling. On the way of searching for an irregular wave analysis procedure to be used in the daily design of lazy-wave riser installation analyses, this work proposes an Artificial Neural Network (ANN)-based approach. The proposed model aims to achieve it by training a convolutional neural network (CNN) fed by generated data from short length finite element-based numerical simulations. This surrogate model can predict quite well the pipe's top tension and approximately the axial tension in the touchdown zone (TDZ) for different configuration stages during the riser's installation operation. Moreover, the proposed model works for different environmental scenarios, which boosts the computational simulation time reduction in this phase of riser design.","PeriodicalId":509714,"journal":{"name":"Journal of Offshore Mechanics and Arctic Engineering","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-06-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141361756","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Eduardo Tadashi Katsuno, Andreas Peters, O. el Moctar
This paper investigates the seakeeping behavior of helicopters after an emergency landing in water, focusing on a Northern North Sea wave climate and considering a realistic helicopter geometry. Computational Fluid Dynamics (CFD) techniques, including the cell-centered Finite Volume Method and Boundary Element Methods (BEM), were utilized to analyze motion responses and load distribution. The study ensures numerical result reliability through best simulation practices. Results indicate that the inviscid model produces similar outcomes to the viscous model in decay tests with roll, pitch, and heave motions. Natural periods for roll, pitch, and heave motions were obtained. Linearity between incident wave amplitude and pitch/heave response was noted for regular waves, while roll linearity was limited for small angles. In irregular wave conditions, helicopters tended to align perpendicular to waves over time, resulting in increased peak roll angles with higher significant wave heights. Exceedance rates of maximum roll peaks, useful for the assessment of capsizing probability, were quantified for different significant wave heights.
{"title":"Numerical Seakeeping Analysis for a Floating Helicopter after Ditching in Waters","authors":"Eduardo Tadashi Katsuno, Andreas Peters, O. el Moctar","doi":"10.1115/1.4065709","DOIUrl":"https://doi.org/10.1115/1.4065709","url":null,"abstract":"\u0000 This paper investigates the seakeeping behavior of helicopters after an emergency landing in water, focusing on a Northern North Sea wave climate and considering a realistic helicopter geometry. Computational Fluid Dynamics (CFD) techniques, including the cell-centered Finite Volume Method and Boundary Element Methods (BEM), were utilized to analyze motion responses and load distribution. The study ensures numerical result reliability through best simulation practices. Results indicate that the inviscid model produces similar outcomes to the viscous model in decay tests with roll, pitch, and heave motions. Natural periods for roll, pitch, and heave motions were obtained. Linearity between incident wave amplitude and pitch/heave response was noted for regular waves, while roll linearity was limited for small angles. In irregular wave conditions, helicopters tended to align perpendicular to waves over time, resulting in increased peak roll angles with higher significant wave heights. Exceedance rates of maximum roll peaks, useful for the assessment of capsizing probability, were quantified for different significant wave heights.","PeriodicalId":509714,"journal":{"name":"Journal of Offshore Mechanics and Arctic Engineering","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-06-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141363506","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Due to the complexity of the integrated Floating Wind Turbine (FWT) system, obtaining reliable results necessitates extensive experiments. This paper conducts a comprehensive study on the motion performance and mooring load responses of a novel 12 MW semi-submersible FWT through model tests carried out in a wave basin. A multi-blade large-scale wind generation system, equipped with a rectifier network, was enhanced and constructed to provide a dependable wind field. And a flexible tower was designed and fabricated, achieving an accurate simulation of the tower's stiffness characteristic and its impact on the overall dynamic response. The marine environmental conditions encompass various combinations of wind, waves, and currents. Rigorous calibration and identification tests were undertaken to validate the environmental conditions and the model system. The findings reveal that, under mild wave parameters, the mooring load is primarily influenced by the resonance response with platform motions, particularly surge resonance. The load effect of wind and current induces mean surge and pitch motions, while their damping effect reduces the standard deviation of responses, notably suppressing the pitch response peak at its natural motion frequency. Wave loads predominantly dictate the vibration range of motion responses. When the current velocity reaches a sufficient magnitude, the coupling effect between current and wave in the wave-frequency region significantly amplifies the mooring response. Notably, motions and mooring loads in the 60° and 90° directions surpass those in the 0° direction, with the maximum responses occurring at 60°.
{"title":"Motion and mooring load responses of a novel 12 MW semi-submersible floating wind turbine: An experimental study","authors":"Jianing Guo, Mingyue Liu, Zhichao Fang, Longfei Xiao, Weimin Chen, Xujie Pan","doi":"10.1115/1.4065601","DOIUrl":"https://doi.org/10.1115/1.4065601","url":null,"abstract":"\u0000 Due to the complexity of the integrated Floating Wind Turbine (FWT) system, obtaining reliable results necessitates extensive experiments. This paper conducts a comprehensive study on the motion performance and mooring load responses of a novel 12 MW semi-submersible FWT through model tests carried out in a wave basin. A multi-blade large-scale wind generation system, equipped with a rectifier network, was enhanced and constructed to provide a dependable wind field. And a flexible tower was designed and fabricated, achieving an accurate simulation of the tower's stiffness characteristic and its impact on the overall dynamic response. The marine environmental conditions encompass various combinations of wind, waves, and currents. Rigorous calibration and identification tests were undertaken to validate the environmental conditions and the model system. The findings reveal that, under mild wave parameters, the mooring load is primarily influenced by the resonance response with platform motions, particularly surge resonance. The load effect of wind and current induces mean surge and pitch motions, while their damping effect reduces the standard deviation of responses, notably suppressing the pitch response peak at its natural motion frequency. Wave loads predominantly dictate the vibration range of motion responses. When the current velocity reaches a sufficient magnitude, the coupling effect between current and wave in the wave-frequency region significantly amplifies the mooring response. Notably, motions and mooring loads in the 60° and 90° directions surpass those in the 0° direction, with the maximum responses occurring at 60°.","PeriodicalId":509714,"journal":{"name":"Journal of Offshore Mechanics and Arctic Engineering","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-05-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141102388","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Profiles of Two JOMAE Associate Editors (The Seventh in a Continuing Series)","authors":"Lance Manuel","doi":"10.1115/1.4065600","DOIUrl":"https://doi.org/10.1115/1.4065600","url":null,"abstract":"","PeriodicalId":509714,"journal":{"name":"Journal of Offshore Mechanics and Arctic Engineering","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-05-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141098724","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Andrea Bertozzi, Francesco Niosi, Xiaoli Jiang, Zhiyu Jiang
Numerical modelling of the floating offshore wind turbine (FOWT) dynamics plays a critical role at the design stage of a floating wind project. Still, there exist challenges for verification of efficient engineering models against experimental results. Recently, an experimental campaign was carried out for a 1:96 downscaled model of the OC4-DeepCWind semi-submersible platform with mooring lines made of fibre ropes and chains. Leveraging the results of this campaign, this paper focuses on development and calibration of a numerical model for the semi-submersible platform with a focus on the dynamic responses under bichromatic waves. In the numerical model, the hydrodynamic loads are modelled based on the potential flow theory with Morison drag. The lumped mass method is applied to model the mooring system. Both free decay tests and bichromatic wave conditions are considered in the model calibration process, and key uncertain parameters (e.g., mooring line length) that affect the response have been identified and discussed. Using the proposed calibration procedure, we establish a reasonably good numerical model for prediction of the platform motion and mooring dynamics. The low-frequency responses of the platform under bichromatic waves are well-captured. These outcomes contribute to the development of efficient numerical FOWT models under experimental uncertainty.
{"title":"Numerical calibration of the mooring system for a semi-submersible floating wind turbine model","authors":"Andrea Bertozzi, Francesco Niosi, Xiaoli Jiang, Zhiyu Jiang","doi":"10.1115/1.4065551","DOIUrl":"https://doi.org/10.1115/1.4065551","url":null,"abstract":"\u0000 Numerical modelling of the floating offshore wind turbine (FOWT) dynamics plays a critical role at the design stage of a floating wind project. Still, there exist challenges for verification of efficient engineering models against experimental results. Recently, an experimental campaign was carried out for a 1:96 downscaled model of the OC4-DeepCWind semi-submersible platform with mooring lines made of fibre ropes and chains. Leveraging the results of this campaign, this paper focuses on development and calibration of a numerical model for the semi-submersible platform with a focus on the dynamic responses under bichromatic waves. In the numerical model, the hydrodynamic loads are modelled based on the potential flow theory with Morison drag. The lumped mass method is applied to model the mooring system. Both free decay tests and bichromatic wave conditions are considered in the model calibration process, and key uncertain parameters (e.g., mooring line length) that affect the response have been identified and discussed. Using the proposed calibration procedure, we establish a reasonably good numerical model for prediction of the platform motion and mooring dynamics. The low-frequency responses of the platform under bichromatic waves are well-captured. These outcomes contribute to the development of efficient numerical FOWT models under experimental uncertainty.","PeriodicalId":509714,"journal":{"name":"Journal of Offshore Mechanics and Arctic Engineering","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-05-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141123209","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A typical fish farm in Norway usually consists of 6 to 12 fish cages, and these fish cages are moored together in a grid shape. Due to wake effects, individual fish cages may experience different flow velocities depending on their positions in the fish farm. Hereby, the drag forces on individual fish cages can be different. The drag forces on the downstream fish cages are difficult to be estimated without knowing the exact flow velocity, which will lead to challenges with the mooring system design. In this study, the computational fluid dynamic (CFD) method combined with a porous media model is employed to investigate the wake effects on the fish farm. The flow field through the fish cages and the drag forces on the downstream fish cages are investigated and discussed.
{"title":"Numerical Investigations on Wake Effects of Fish Cages","authors":"Hui Cheng, Onur Aydemir, M. Ong","doi":"10.1115/1.4065508","DOIUrl":"https://doi.org/10.1115/1.4065508","url":null,"abstract":"\u0000 A typical fish farm in Norway usually consists of 6 to 12 fish cages, and these fish cages are moored together in a grid shape. Due to wake effects, individual fish cages may experience different flow velocities depending on their positions in the fish farm. Hereby, the drag forces on individual fish cages can be different. The drag forces on the downstream fish cages are difficult to be estimated without knowing the exact flow velocity, which will lead to challenges with the mooring system design. In this study, the computational fluid dynamic (CFD) method combined with a porous media model is employed to investigate the wake effects on the fish farm. The flow field through the fish cages and the drag forces on the downstream fish cages are investigated and discussed.","PeriodicalId":509714,"journal":{"name":"Journal of Offshore Mechanics and Arctic Engineering","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-05-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140991888","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Floating bridges face potential hazards due to ship collisions throughout their operational lifetime. In the situation where a pontoon is significantly damaged from an accident, a floating drydock may be used to compensate for the lost buoyancy and provide a dry atmosphere for operations. As the repair might take months, a primary concern is whether the repair can be in-site conducted without shutting down the road traffic. This study aims to investigate the feasibility of using a drydock for the repair. The numerical model of the in-operation damaged bridge is established for a comparative dynamic analysis with the intact end-anchored bridge. Eigenvalue analysis is conducted and pendulum modes of oscillation are found with an eigen-period of around 15s. The dynamic responses are analyzed through a series of fully coupled time-domain simulations under various environmental conditions. The results indicate that the standard deviation of the moment about the girder weak-axis increases significantly at the damaged pontoon axis due to the excitation of low-frequency resonant response. Swell wave loads might induce dynamic amplification to the damaged bridge, even with a relatively small wave height. In addition, the internal stress of the bridge girder is investigated and found to be larger, especially, at the lower locations of the cross-section. It is suggested that the responses can be managed by limiting the excitation of pendulum modes or providing special damping devices in practical engineering.
{"title":"NUMERICAL MODELING AND DYNAMIC RESPONSE ANALYSIS OF AN END-ANCHORED FLOATING BRIDGE WITH A DAMAGED PONTOON UNDER REPAIR OPERATION","authors":"Minghao Cui, Zhengshun Cheng, Peng Chen, T. Moan","doi":"10.1115/1.4065387","DOIUrl":"https://doi.org/10.1115/1.4065387","url":null,"abstract":"\u0000 Floating bridges face potential hazards due to ship collisions throughout their operational lifetime. In the situation where a pontoon is significantly damaged from an accident, a floating drydock may be used to compensate for the lost buoyancy and provide a dry atmosphere for operations. As the repair might take months, a primary concern is whether the repair can be in-site conducted without shutting down the road traffic. This study aims to investigate the feasibility of using a drydock for the repair. The numerical model of the in-operation damaged bridge is established for a comparative dynamic analysis with the intact end-anchored bridge. Eigenvalue analysis is conducted and pendulum modes of oscillation are found with an eigen-period of around 15s. The dynamic responses are analyzed through a series of fully coupled time-domain simulations under various environmental conditions. The results indicate that the standard deviation of the moment about the girder weak-axis increases significantly at the damaged pontoon axis due to the excitation of low-frequency resonant response. Swell wave loads might induce dynamic amplification to the damaged bridge, even with a relatively small wave height. In addition, the internal stress of the bridge girder is investigated and found to be larger, especially, at the lower locations of the cross-section. It is suggested that the responses can be managed by limiting the excitation of pendulum modes or providing special damping devices in practical engineering.","PeriodicalId":509714,"journal":{"name":"Journal of Offshore Mechanics and Arctic Engineering","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-04-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140669277","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：