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![3D displacement distribution of uz due to transient point load for various time instants. Implementation of the proposed solution to transient point load shows full agreement with the existing solution in [25].](publication/328530818/figure/fig9/AS:1086453694103581@1636042154309/3D-displacement-distribution-of-uz-due-to-transient-point-load-for-various-time-instants.jpg)
3D displacement distribution of uz due to transient point load for various time instants. Implementation of the proposed solution to transient point load shows full agreement with the existing solution in [25].
Source publication
Wave-induced dynamic loads yield displacement and stress propagation on the seabed beneath the offshore wind turbine foundation. Existing attempts to calculate the displacement/stress propagation based on commercial software packages or numerical solvers usually ignore the inertial effects and provide quasi-static solution for the dynamic problem o...
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Citations
... The rotation center of the suction bucket decreases with increasing scouring depth. Based on the integral transformation and the stress function, G. Pavlou et al. (Pavlou and Li, 2018) obtained an accurate analytical solution for the dynamic response of an offshore wind turbine foundation under vertical harmonic excitation, primarily considering wave-induced dynamic loadings. Ding et al. (2020b) studied the load-bearing performance of composite bucket foundations in terms of deformation, load-bearing ratio, and geometric effects through a series of numerical simulations. ...
Offshore wind turbines are sensitive to tilt failures due to earthquake excitation. Soil liquefaction must be checked in seismically active areas. This study investigates the seismic response of suction bucket foundations in offshore wind turbines that are subjected to earthquake loadings. A series of shaking table tests are performed in a centrifuge, and a numerical analysis is performed in OpenSees and verified against centrifuge tests. The distribution law of the effective stress and excess pore water pressure ratio at the site is also analyzed. A parametric study is conducted by evaluating the influence of bucket configurations, overburden pressures, and seismic intensities. The soil inside and below the bucket foundation is strengthened and resists liquefaction more effectively. The bucket diameter and overburden pressure are key factors in enhancing seismic stability. The anti-liquefaction improvement ratio is assessed, and the distribution law of the anti-liquefaction performance of the soil in the area affected by the additional stress is described. A correction factor is proposed to modify the additional stress ratio by considering the distribution law of pore water pressure. This study provides a revised method to estimate the anti-liquefaction performance of the suction bucket foundation.
... Still, there is need for further exploration of the pipe-buckling during situations such as movement of subsoil or liquefaction of subsoil under earthquake forces or the lateral or vertical movement of pipeline under various hydrodynamic loading [5][6][7]. The pipe-soil interaction should also be studied in detail for the internal flow [8][9][10] and the oscillating working platform [11] induced vibration in pipe. ...
... A schematic diagram showing the direction and location of the forces used in the Equation(6) to Equation(18). ...
The buckling analysis of an offshore pipeline refers to the analysis of temperature-induced uplift and lateral buckling of pipelines by analytical, numerical, and experimental means. Thus, the current study discusses different research performed on thermal pipe-buckling and the different factors affecting the pipeline’s buckling behaviour. The current study consists of the dependency of the pipe-buckling direction on the seabed features and burial condition; the pre-buckling and post-buckling load-displacement behaviour of the pipeline; the effect of soil weight, burial depth, axial resistance, imperfection amplitude, temperature difference, interface tensile capacity, and diameter-to-thickness ratio on the uplift and lateral resistance; and the failure mechanism of the pipeline. Moreover, the effect of external hydrostatic pressure, bending moment, initial imperfection, sectional rigidity, and diameter-to-thickness ratio of the pipeline on collapse load of the pipeline during buckling were also included in the study. This work highlights the existing knowledge on the topic along with the main findings performed up to recent research. In addition, the reference literature on the topic is given and analysed to contribute to a broad perspective on buckling analysis of offshore pipelines. This work provides a starting point to identify further innovation and development guidelines for professionals and researchers dealing with offshore pipelines, which are key infrastructures for numerous maritime applications.
... The interactions between ocean surface waves and structures have significant 33 importance in various environmental and engineering problems, such as the safety and 34 durability of coastal/offshore structures (Liu et al., 2009;Pavlou and Li, 2018) . Therefore, vast scientific and financial resources are being spent studying these 40 processes, including performing physical tests and developing prediction models. ...
Machine learning techniques have inspired reduced-order solutions in the fluid mechanics' field that benefit from unprecedented capability and efficiency. Targeting ocean-wave problems, this work has developed a novel data-driven computational approach, named Wave-GAN. This new tool is based upon the conditional Generative Adversarial Network (GAN) principle, and it provides the ability to predict three-dimensional nonlinear wave loads and run-up on a fixed structure. The paper presents the principle of Wave-GAN and an application example of regular waves interacting with a vertical fixed cylinder. Computational Fluid Dynamics (CFD) is used to provide training and testing datasets for the Wave-GAN deep learning network. Upon verification, Wave-GAN proved the ability to provide accurate results for predicting wave load and run-up for wave conditions that were not informed during training. Yet the CFD-comparative results were only obtained within seconds by the deep learning tool. The promising results demonstrate Wave-GAN's outstanding potential to act as a pioneering sample of applying machine learning techniques to ocean-wave interaction problems. It is envisioned that the new approach could be extended to more complex shapes and wave conditions to facilitate the early design stage of marine and offshore engineering applications such as monopiles. As a result, enhanced reliability is expected to prevent environmental disasters in the offshore industry.
... Another very important load when studying offshore structures is the wave load [67,68]. In extreme conditions, the waves' strength may be very high, and it can induce a significant force on the structure. ...
Countries around the world generate electricity from renewable resources to decarbonise their societies and reduce global warming. Some countries have already outlined their wishes to produce a part of their total energy consumption from renewable sources in the coming years and gradually reduce the use of nuclear energy and fossil fuel in favour of cleaner fuels. While renewable energies are significant factors in tackling climate change, the parameters that can influence their performance should be analysed in detail during the design process. One of these parameters is the foundation of an offshore wind turbine. Offshore wind turbines allow more energy to be produced than an onshore installation, and do not have any harmful effects on human beings, while their geotechnical aspects need to be clearly determined in advance. In this study, the influential parameters such as soil type, the number of bolts in the design, and the size of the structure were analysed using the finite element method for three different designs. The simulations showed that some soil properties, such as cohesion, do not influence the results, while Young's modulus has a large influence on the designs. Additionally, the results of this study showed that the maximum stress concentrations are at the bolts and connection joints where they are too close to the steel's yield stress. It also proves that the non-elastic behaviour of the soil does not require to be assigned for such analyses and it can be simplified only with its elastic behaviour. The embedded length affects the lateral displacement, while the number of bolts influences the structure's resistance to external loads.
... In Ref. [16], a dynamic response of offshore wind turbine foundation under vertical harmonic loads is attempted. Unlike the works [10,11,14], the inertial effects of the soil are considered, and the proposed solution is purely analytical. ...
... In the light of Eq. (20), it can be concluded that for the sake of determining the monopile dynamic response in the range of frequencies of wave loads, the soil parameter K s given in Eq. (16) can be adequately approximated by ...
The structural design of offshore wind turbines is based on the consideration of coupled dynamic phenomena. Wave loads cause the dynamic oscillation of the monopile, and the dynamic oscillation of the monopile affects the wave loads. The boundary conditions of the gravity-based foundation-monopile-turbine system are mostly affected by the flexural stiffness of the foundation plate, the elastic and creep behavior of the soil, and the inertia (translational and rotational) of the wind turbine mass. The design of the foundation should consider the dynamic response of the soil and the monopile, and the dynamic response of the soil and the monopile is affected by the design parameters of the foundation. The initial conditions of the system yield transient dynamic phenomena. A braking wave at t = 0 causes different dynamic response than the steady-state conditions due to a harmonic wave load. In the present work, an integrated analytical model simulating the above dynamic phenomena is proposed. With the aid of double integral transforms and generalized function properties, a solution of the corresponding differential equations for the monopile-soil-foundation system and the boundary and initial conditions is derived. A parametric study is carried out, and results of the effect of the design parameters and soil properties are presented and discussed.
... In Ref. [16], a dynamic response of offshore wind turbine foundation under vertical harmonic loads is attempted. Unlike the works [10,11,14], the inertial effects of the soil are considered, and the proposed solution is purely analytical. ...
... In the light of Eq. (20), it can be concluded that for the sake of determining the monopile dynamic response in the range of frequencies of wave loads, the soil parameter K s given in Eq. (16) can be adequately approximated by ...
An analytical solution for the dynamic response of submerged slender circular cylindrical structures subjected to linear wave loads is presented. A double Laplace transform with respect to temporal and spatial variables is applied both to motion equation and boundary conditions. The dynamic deflection of the beam is obtained by inversion of the Laplace transform. The latter with respect to spatial variable is obtained analytically, while the one concerning the temporal variable is numerically calculated using Durbin numerical scheme. Results in the case of a representative example for a monopile foundation subjected to Airy waves are presented and discussed, and the analytical result is compared against numerical dynamic and static solutions.
... Still, there is need for further exploration of the pipe-buckling during situations such as movement of subsoil or liquefaction of subsoil under earthquake forces or the lateral or vertical movement of pipeline under various hydrodynamic loading [5][6][7]. The pipe-soil interaction should also be studied in detail for the internal flow [8][9][10] and the oscillating working platform [11] induced vibration in pipe. ...
... A schematic diagram showing the direction and location of the forces used in the Equation(6) to Equation(18). ...
Subsea pipelines operating under high pressures and temperatures are typically buried to protect from the environmental impacts and to prevent the instigation of global buckling. As the seabed profile is generally uneven, certain initial imperfections generally exist along the pipeline. As the pipe traverses in shallow waters, the seabed can be subjected to hydrodynamic loads caused by surface gravity waves. The hydrodynamic pressure, which typically depends on the wave height and water depth, leads to the development of pore pressures within the soil medium. This gradient of the pore pressures can cause significant uplift forces on the pipe, which may initiate the buckling in the vicinity of the imperfection. This study focuses on understanding the influence of these wave induced uplift forces on the buckling of the initial imperfect pipelines. Four typical imperfection profiles are considered in the study. The influence of imperfection shape on the buckling behavior is compared for surface laid and buried pipelines. Thereafter buckling behavior of the considered imperfect pipelines is studied with and without consideration of wave loads for a range of wave particulars and burial depths. The wave forces on the pipeline are estimated by solving Biot’s consolidation equations using finite element software COMSOL and the buckling studies are carried out using ABAQUS.
