A review of vibration control methods for marine offshore structures

Ramkumar, K.; Cui, Fangsen; Townsend, Nicholas; Foo, Chuan-Sheng; Guo, Junyan; Shenoi, Ajit; Xiong, Yeping

doi:10.1016/j.oceaneng.2016.10.001

Cited by 172 publications

(54 citation statements)

References 91 publications

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“…From this graph, it is clear that first natural frequency decreases with increase in test time of corrosion acceleration and cracking area (Tapan & Aboutaha, 2011). Where a variation in first natural frequency of beam specimen is similar and progresses with a little desperation until there is no cover loss and reduction in moment of inertia of beam specimen and similar observations are given by M. Fayyadh, H. Razak and Z. Ismail (2011), R. Kandasamya et al (2016).…”

Section: Resultssupporting

confidence: 70%

Corrosion Impact Analysis on Residual Life of Structure Using Cathodic Technique and Algor Simulation Software

Nayak

Throat

Thakare³

2018

Engineering Structures and Technologies

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Abstract. Damage to the reinforced concrete structure is mainly occurring because of two reasons either due to end of service life or due to load exceeds beyond structural capacity. Along with these two reasons degradation of material property is the one more major factor which causes the risk of failure. A concrete structure constructed in an aqueous environment get exposed to the corrosion process. Consequently, this causes the generation of crack, fragilization, a decrease of bond strength between reinforcement and concrete. All these factors affection static and dynamic behavior of concrete structure reducing the service life of an affected area. Whereas service life carries the major role in the economy of a concrete structure that is why various methods have been developed in the second half of the 20 th century to find out the residual life of the structure. In this proposed work, a non-destructive technique is used to predict the residual life of reinforced concrete beams having different cracking levels, as results of steel reinforcement corrosion, considering the variation produced in the dynamic behavior, through the variation of the first natural vibration frequency. Whereas to accelerate the corrosion process, impress current technique is used in which a current is externally applied to induce corrosion in reinforcement and then crack widths and vibration natural frequencies were measured. A numerical model is proposed with the help of FEM based Auto desk Algor simulation software to predict attack penetration depth. At the end, the paper is concluded by giving an effect of "water to cement ratio" and "cover to diameter ratio" on the initiation and propagation of corrosion and residual life of corroded beam specimen is graphically represented.

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Section: Resultssupporting

confidence: 70%

Corrosion Impact Analysis on Residual Life of Structure Using Cathodic Technique and Algor Simulation Software

Nayak

Throat

Thakare³

2018

Engineering Structures and Technologies

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“…Therefore, the optimal irregular wave disturbances attenuation problem can be formulated as designing the digital-control-based AOWDAC u * (k) for a nonlinear offshore platform (2) and wave forces (9) so that the average quadratic performance index (12) can be obtained the minimum value.…”

Section: Discrete Optimal Irregular Wave Disturbances Attenuation Promentioning

confidence: 99%

“…Offshore platforms generally involve sophistication of the superstructure in the deep water, in which various inevitable factors directly affect offshore platforms in ocean environment, especially vibration caused by external wave force [9]. In order to describe and identify the characteristic of wave force, various idealized spectra are employed to describe the empirical relationship that defines the distribution of energy with frequency within the ocean [10], such as the Pierson-Moskowitz spectrum [11] and Joint North Sea Wave Project (JONSWAP) spectrum [12].…”

Section: Introductionmentioning

confidence: 99%

Digital-Control-Based Approximation of Optimal Wave Disturbances Attenuation for Nonlinear Offshore Platforms

et al. 2017

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Abstract:The irregular wave disturbance attenuation problem for jacket-type offshore platforms involving the nonlinear characteristics is studied. The main contribution is that a digital-control-based approximation of optimal wave disturbances attenuation controller (AOWDAC) is proposed based on iteration control theory, which consists of a feedback item of offshore state, a feedforward item of wave force and a nonlinear compensated component with iterative sequences. More specifically, by discussing the discrete model of nonlinear offshore platform subject to wave forces generated from the Joint North Sea Wave Project (JONSWAP) wave spectrum and linearized wave theory, the original wave disturbances attenuation problem is formulated as the nonlinear two-point-boundary-value (TPBV) problem. By introducing two vector sequences of system states and nonlinear compensated item, the solution of introduced nonlinear TPBV problem is obtained. Then, a numerical algorithm is designed to realize the feasibility of AOWDAC based on the deviation of performance index between the adjacent iteration processes. Finally, applied the proposed AOWDAC to a jacket-type offshore platform in Bohai Bay, the vibration amplitudes of the displacement and the velocity, and the required energy consumption can be reduced significantly.

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“…Considerable research efforts have been made to suppress the adverse vibrations of offshore platforms, and various control methods have been proposed. These methods can be roughly classified as the passive, active, semiactive, and hybrid methods . Compared with the other control systems, passive methods require no external energy input and are widely used in engineering practice.…”

Section: Introductionmentioning

confidence: 99%

A novel rotational inertia damper for heave motion suppression of semisubmersible platform in the shallow sea

Hao

2019

Struct Control Health Monit

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Semisubmersible platforms (SSPs) have been widely used in the offshore industries for energy exploitation. SSP is vulnerable to the heave motions, and continuous heave motions may cause fatigue damage to the structural and nonstructural members or even sinking of the platform. It is therefore imperative to suppress the undesired heave motions of SSP. In the present study, a novel hydraulic rotational inertia damper (RID), which can amplify the fluid resistance of the submerged plates, is proposed on the basis of the concept of inerter to mitigate the heave motions of SSP. Analytical studies are conducted in both the frequency and time domains to investigate the control effectiveness of the proposed method. For comparison, the responses of the SSP controlled by the commonly adopted fixed heave plate (FHP) and tuned heave plate (THP) are also calculated. Analytical results show that the proposed RID system is more effective in reducing the heave motions of SSP, and it can achieve the identical control performance of the FHP and THP systems by using a much smaller plate size, thus smaller physical mass (less than 0.8% of the mass of the heave plate in this research). Furthermore, it is found that the RID system performs better in the harsher wave conditions, and its effectiveness increases with the increase of wave height. The proposed method provides an attractive alternative to effectively and economically suppress the heave motions of SSP in the shallow sea.KEYWORDS fixed heave plate, heave motion suppression, inerter, rotational inertia damper, semisubmersible platform, tuned heave plate SSP is most widely applied due to its wider range of applicable water depth, larger deck area, and bigger payload capacity. However, the shallow draft and large pontoons of SSP may lead to the excessive heave motion to the platform. These continuous vibrations may not only result in the fatigue damage to the structural/nonstructural components but also affect the health of the crew and reduce the serviceability and efficiency of the platform. The aim of the present study is to propose a novel method to suppress the excessive heave motion of SSP in the shallow sea.Considerable research efforts have been made to suppress the adverse vibrations of offshore platforms, and various control methods have been proposed. These methods can be roughly classified as the passive, active, semiactive, and hybrid methods. 3 Compared with the other control systems, passive methods require no external energy input and are widely used in engineering practice. For SSP, the most commonly utilized passive method is to install a ballast or fixed heave plate (FHP) at the bottom of the platform to increase the added mass/damping of the system. The effectiveness of using FHP for SSP heave motion mitigation has been verified through both numerical and experimental studies by many researchers. 4,5 Instead of rigidly connecting the SSP and heave plate, tuned heave plate (THP) has also been developed recently to further improve the performance of the control ...

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A review of vibration control methods for marine offshore structures

Cited by 172 publications

References 91 publications

Corrosion Impact Analysis on Residual Life of Structure Using Cathodic Technique and Algor Simulation Software

Corrosion Impact Analysis on Residual Life of Structure Using Cathodic Technique and Algor Simulation Software

Digital-Control-Based Approximation of Optimal Wave Disturbances Attenuation for Nonlinear Offshore Platforms

A novel rotational inertia damper for heave motion suppression of semisubmersible platform in the shallow sea

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