Essentials of Offshore Structures

Reddy, D.V.; Swamidas, A. S. J.

doi:10.1201/b15033

Cited by 9 publications

(12 citation statements)

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“…Here, the equation of motion is again used to estimate the ship response to the tsunami current in the HDG-normal direction: where v and v c are ship response velocity and tsunami current, respectively. C D and C M are constant coefficients of drag force and inertia force (Dean and Dalrymple 1985;Reddy and Swamidas 2013). B is the breadth of the ship.…”

Section: Simulating Ship Response and Tsunami Currentmentioning

confidence: 99%

Extracting clearer tsunami currents from shipborne Automatic Identification System data using ship yaw and equation of ship response

Inazu

Ikeya

Iseki

et al. 2020

Earth Planets Space

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We have explored tsunami current signals in maritime Automatic Identification System (AIS) data during the 2011 Tohoku, Japan, tsunami. The AIS data were investigated in detail taking into account ship motion and response to tsunami current. Ship velocity derived from AIS data was divided into two components in terms of the ship heading: heading-normal and heading-parallel directions. The heading-normal velocity showed good agreement with the simulated tsunami current, as mentioned in our former research. Here, we found the heading-normal velocity was contaminated by non-tsunami noises that were mostly related to the ship yaw motion around the pivot point. The noises due to the yaw motion were reasonably corrected in the heading-normal velocity. The corrected headingnormal velocity clearly showed better agreement with the simulated tsunami current. Although the heading-parallel velocity is basically the navigation speed, and is mostly controlled by ships' captain, we could find the heading-parallel velocity was also drifted by tsunami currents. The corrected heading-normal velocity was still a ship response to the tsunami current. Based on an equation of a ship response to tsunami currents, we numerically estimated tsunami current from the corrected heading-normal velocity. We could find very slight improvements in estimating the tsunami currents, which indicated that this operation possibly worked as a secondary correction. Tsunami currents of tens of centimeters per second are expected to be suitably detected using AIS based on discussion on detection limit.

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Section: Simulating Ship Response and Tsunami Currentmentioning

confidence: 99%

Extracting clearer tsunami currents from shipborne Automatic Identification System data using ship yaw and equation of ship response

Inazu

Ikeya

Iseki

et al. 2020

Earth Planets Space

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“…We evaluate the relationship between the ship velocity and the tsunami current ( Fig. 5) using an equation of motion of a movable floating body (Reddy and Swamidas 2013). The floating body is the navigating vessel.…”

Section: Measurable Tsunami Currentmentioning

confidence: 99%

“…D, L, and B are given by static information from AIS data ( Table 1). The equation is often rewritten as (Reddy and Swamidas 2013):…”

Section: Measurable Tsunami Currentmentioning

confidence: 99%

Measuring offshore tsunami currents using ship navigation records

Inazu

Ikeya

Waseda

et al. 2018

Prog Earth Planet Sci

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We investigated ship navigation records known as Automatic Identification System (AIS) data near the source region of the 2011 Tohoku, Japan, tsunami. The AIS data of 16 ships in the offshore navigation could be compiled by about 40 min after the tsunami generation. Most of the AIS data showed notable deviation of the ship heading from the course over ground during the tsunami passage. There was good agreement in terms of amplitude/phase between the ship velocity and the simulated tsunami velocity in the direction normal to the ship heading. An equation of motion due to wave drag and inertia forces was examined for an offshore movable floating body. We explain that the ship movement in the direction normal to the heading immediately responds to the tsunami current, and relative velocity between the ship and the tsunami current asymptotically become zero. This indicates the movement velocity of navigating ships in the direction normal to the heading derived from AIS data will work as an offshore tsunami current meter. We examined the AIS data during the 2011 Tohoku tsunami and showed these data could be useful for tsunami source estimation and forecast. The AIS data in the current framework will possibly be a crowd-sourced tool for monitoring offshore tsunami current and tsunami forecast.

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“…The substructure must sustain the topside facilities against environmental loads, providing a safe working area. An offshore structure is expected to fulfil certain functional requirements and be in a state of static and dynamic equilibrium during their lifetime [12]. A Jacket is a fixed platform substructure which has three main functions i) Support the topside and equipment's; ii) provide resistance against environmental loads; and iii) protect the well conductors [12].…”

Section: Offshore Fixed Structures -Jacketsmentioning

confidence: 99%

“…The jackets are fixed to the sea bottom thru pile foundations, with diameters up to 3 m. These piles are driven to depth that can range from 40 to 120 m below the sea bed. The connection between the piles and the jacket legs have three main solutions, i) Piles through the legs, in this case the piles are driven along the whole length and inside the leg, ii) skirt-Piles through sleeves, where the piles are also driven along the length of the legs, but through guides attached to the legs, iii) Vertical piles driven directly through pile sleeves attached to the bottom of jacket legs, these sleeves are also called pile cluster [12], see Fig. 7(a) and Fig.…”

Section: Robustness Redundancy and Progressive Collapsementioning

confidence: 99%

Robustness, Redundancy and Progressive Collapse of Fixed Offshore Structures

et al. 2017

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The purpose of this paper is to present an evaluation of the robustness of fixed offshore structures, through the understanding of, i) major historical accidents, and its repercussions in the codes and regulations, ii) review the methods used to assure robustness, with special focus in offshore standards, but also with civil Eurocodes; iii) Robustness assessment and measurement and, iv) which factors and mechanical properties of structures influences robustness. To be able to measure the Robustness of a structure under accidental or unforeseen events it is necessary to quantify its ultimate capacity and establish its post collapse behaviour. Therefore, a case study consisting of Non-Linear analysis (pushover) of a fourlegged jacket is developed using USFOS software, where several structural properties are made variable and the effect in the robustness is measured.

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Essentials of Offshore Structures

Cited by 9 publications

References 0 publications

Extracting clearer tsunami currents from shipborne Automatic Identification System data using ship yaw and equation of ship response

Extracting clearer tsunami currents from shipborne Automatic Identification System data using ship yaw and equation of ship response

Measuring offshore tsunami currents using ship navigation records

Robustness, Redundancy and Progressive Collapse of Fixed Offshore Structures

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