Journal Article•
Wave forces on a vertical cylinder defenced by a perforated vertical and inclined barriers
01 Sep 2002-Indian Journal of Marine Sciences (Council of Scientific & Industrial Research)-Vol. 31, Iss: 3, pp 179-187
TL;DR: Wave forces on a vertical cylinder defensed by a perforated vertical and inclined barriers with 45° angle of inclination were experimentally investigated and the force ratios were found reducing with increase of wave steepness.
Abstract: Wave forces on a vertical cylinder defensed by a perforated vertical and inclined barriers with 45° angle of inclination were experimentally investigated. The relative wave height, (H i /d) varied from 0.114 to 0.429 and the porosity was kept constant with 12%. The force ratios were found reducing with increase of H i /d. It is estimated that on an average, the reduction of force on the vertical cylinder is about 35% due to perforated vertical barrier and is about 30% due to sloped barrier. Incident wave steepness, (H i /L) varied from 0.007 to 0. 080 and the force ratios were also found reducing with increase of wave steepness. The force ratios are less sensitive for the scattering parameter (ka).
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Book•
22 Feb 2015
TL;DR: The newly evolved structural forms and their discrete characteristics are discussed in this chapter and gives the reader a good understanding about the structural action of different forms in the offshore.
Abstract: This chapter deals with the evolution of platform and various types of offshore platforms and their structural action under different environmental loads. The newly evolved structural forms and their discrete characteristics are discussed in this chapter. This chapter also gives the reader a good understanding about the structural action of different forms in the offshore. An overview of the construction stages of offshore plants and their foundation systems is presented.
49 citations
TL;DR: In this article, a physical model study is carried out to assess the wave forces acting on a single and twin wave barriers of various porosities under a wide range of wave conditions.
Abstract: Vertical slotted barriers are cost effective energy-dissipating structures The design of such barriers requires an accurate estimation of dynamic pressures and resulting wave forces Herein, a physical model study is carried out to assess the wave forces acting on a single and twin wave barriers of various porosities under a wide range of wave conditions The study provides explicit data on how dynamic pressures vary vertically from the seabed to the still water surface and on the resulting forces, both seaward and shoreward In particular, the experimental results indicate that porosity affects dynamic pressures significantly especially near the free surface, but less so closer to the seabed Further, resultant horizontal wave forces seaward are 20–25% less than shoreward forces Forces on the front panel in the twin wave barrier cases are 20–25% more than those on a single porous wall while the forces on the rear or second barrier is always 20–25% less than the single wave-barrier case under identical test conditions These and other results presented in the study can be useful in designing wave dissipaters, especially for inner harbors and vertical sea walls
12 citations
TL;DR: In this paper, the authors investigated the effects of various angles of inclination on the reflection coefficient, transmission coefficient, and loss coefficient of highly pervious pipe breakwaters and found that the influence of inclined pipe breakwater varies according to the effect of minimum reflectivity.
Abstract: This study investigates highly pervious dense pipes with small apertures, which benefit convection and the interchange of seawater within harbor districts and provide effective wave absorption. Additionally, this study explored the problems of wave impacts on the inclined state of highly pervious pipe obstacle, the energy dissipation characteristics for a series of inclined pipe breakwaters, and the relationship between the inclination angle and the dissipation effect. Pipe breakwaters were arranged in diverse angles of inclination. Forward inclination replicated the effects of a concave embankment, and backward inclination replicated the inclined plane of a sloping revetment. Physical experiments were conducted to investigate the influence that various apertures and inclined angles have on reflection coefficient, transmission coefficient, and loss coefficient. The results show that the influence of highly pervious inclined permeable breakwaters varies according to the effect of minimum reflectivity. The attenuation of long waves is ineffective compared to the efficacy for short waves. Lengthening the pipe enhances the effects of attenuation more compared to shifting the inclination angle, and shifting the inclination angle enhances the effects more than enlarging the aperture.
12 citations
TL;DR: In this paper, a scaled model of the TLP with the perforated columns was investigated under regular waves and it was shown that there is a significant reduction in the dynamic response of the column members.
Abstract: Tension-Leg Platforms (TLPs) are commonly preferred offshore structures for the deep-water oil exploration. Their reduced response to the encountered waves is achieved by their compliancy. This innovative structural design dampens the vertical motion (heave) of the platform but the large horizontal movements (surge, sway and yaw motion) cause inconvenience to the people on board, though the platform remains stable for the operational sea state. Coastal and offshore structures are constructed with the protective perforated layers mainly to reduce the direct impact caused by the waves. Present study highlights the detailed experimental investigations carried out on the scaled model of the TLP with the perforated members under regular waves. Based on the experimental investigations, it is seen that there is a significant reduction in the dynamic response of the TLP with the perforated columns. Encompassing column members with the perforated outer cover is seen as one of the effective method of retrofitting o...
10 citations
TL;DR: In this paper, a well-planned physical model study is carried out for this purpose on single and twin wave barriers of various porosities under a wide range of random wave conditions, and the experimental results indicate that the porosity affects the dynamic pressures significantly, especially near the free surface, but less so closer to the seabed.
Abstract: The use of vertical slotted barriers can be a cost effective solution for wave energy dissipation when sloped rubble structures are not desirable. For a cost-effective design of such barriers, an accurate estimation of dynamic pressures and wave forces is needed. A well-planned physical model study is carried out for this purpose on single and twin wave barriers of various porosities under a wide range of random wave conditions. This study provides explicit data for the vertical variation of the dynamic pressures from the seabed to the still water surface and for the resulting forces, both seaward and shoreward. The experimental results indicate that the porosity affects the dynamic pressures significantly, especially near the free surface, but less so closer to the seabed. Further, the resultant seaward horizontal wave forces are 20% to 25% less than the shoreward forces. Forces on the front panel in the twin wave barrier cases are 20% to 25% greater than those on a single porous wall, whereas the forces on the rear or second barrier are always 20% to 25% less than those on the single wave barrier under identical test conditions. These and other results presented in the study can be used for designing wave dissipaters, especially for inner harbors and vertical sea walls.
9 citations
References
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2,124 citations
01 Dec 1954
TL;DR: In this paper, a quantitative understanding of the forces developed by wave action against circular piling is presented, where the authors focus on the effect of wave action on circular piling and show that wave action is a powerful force against piling.
Abstract: : Although circular piling is a much-used structural element in shore protection, harbor, and other maritime structures, only recently have significant advances been made toward gaining a quantitative understanding of the forces developed by wave action against piling. The present report deals with this subject.
501 citations
196 citations
Proceedings Article•
01 Jan 1950
167 citations