The Influence of Different Scenarios of Supply Ship Collision on the Dynamic Response of a North-Sea Jacket-Pile-Soil System

Author(s):  
M. Reza Emami Azadi

In the present study, the influence of various scenarios of supply ship collisions, namely, bow, stern and also broad-side impacts on a jacket-pile-soil system is investigated. In the previous study of ship impact on an 8-leg North-Sea Jacket Platform by Amdahl et al. [2] and also other authors, the effect of jacket-pile-soil interaction was not considered. The collision points on the jacket structure are also taken as joints and mid-span of leg, horizontal and vertical braces, namely, hard and soft impact points. The speed and the weight of the colliding vessel are also varied for typical supply vessels. Several supply ship collision analyses are carried out for bow, stern and broad-side impact scenarios on an 8-leg North-sea Jacket platform It is observed that by taking into account the jacket-pile-soil interaction effects, in particular in softer clay soils the amplitude of displacement response after supply ship impact at the deck level is increased due to yield in the upper soil layers. Contrary to this finding, less linear dynamic effects can be seen in the studied jacket-pile-soil system subjected to the supply ship impact. It can also be concluded that for soft impact scenario, the dynamic effects in the global response of the platform located in the mainly OC clayey soil may be much less than those for hard impact scenario on the same platform. For instance, for a brace impact at its mid-span, a less significant dynamic effect has been observed than for a leg impact. The duration of impact in such cases is shown to play an important role in determining the dynamic influence of the platform response. The relative energy absorption of the platform is shown to be more for broad-side loading. It is shown that the global response of the jacket platform during the collision with a supply vessel might depend largely on the scenario of the impact and to some extent on the pile-soil behavior. It is found that for the bow and stern impact scenarios, the energy contribution of the local member dent or buckling might be more significant than for the broad-side loading for which the global frame energy contribution and the overall inertia effect of the platform might be a dominant factor.

Author(s):  
M. R. Emami Azadi

In the present study, the influence of various scenarios of supply ship collisions, namely, bow, stern, and also broad-side impacts on a jacket-pile-soil system, is investigated. In the previous study of ship impact on an eight-leg North-Sea jacket platform by Amdahl and other authors, the effect of jacket-pile-soil interaction was not considered. The collision points on the jacket structure are also taken as joints and midspan of leg, horizontal and vertical braces, namely, hard and soft impact points. The speed and the weight of the colliding vessel are also varied for typical supply vessels. Several supply ship collision analyses are carried out for bow, stern and broad-side impact scenarios on an eight-leg North-Sea jacket platform. It is observed that by taking into account the jacket-pile-soil interaction effects, particularly in softer clayey soils, the amplitude of displacement response after the supply ship impact at the deck level is increased due to yield in the upper soil layers. Contrary to this finding, less linear dynamic effects can be seen in the studied jacket-pile-soil system subjected to the supply ship impact. It can also be concluded that for a soft impact scenario, the dynamic effects in the global response of the platform located in the mainly over-consolidated (OC) clayey soil may be much less than those for a hard impact scenario on the same platform. For instance, for a brace impact at its midspan, a less significant dynamic effect has been observed than for a leg impact. The duration of impact in such cases is shown to play an important role in determining the dynamic influence of the platform response. The relative energy absorption of the platform is shown to be more for broad-side loading. It is shown that the global response of the jacket platform during the collision with a supply vessel might depend largely on the scenario of the impact and, to some extent, on the pile-soil behavior. It is found that for the bow and stern impact scenarios, the energy contribution of the local member dent or buckling might be more significant than that for the broad-side loading for which the global frame energy contribution and the overall inertia effect of the platform might be a dominant factor.


Author(s):  
Yanyan Sha ◽  
Jørgen Amdahl

The Norwegian Public Roads Administration is running a project “Ferry free coastal route E39” which includes replacing ferry crossings by bridges or tunnels across fjords in Western Norway. A floating bridge concept was proposed in the fjord-crossing project for Bjørnefjorden. As there are regular cruise routes passing by the bridge, it raises the concern for the consequences of accidental ship collision with the bridge girder. During the collision, the interactions between the bridge girder and the ship structure can be significant. Thus, in the design of the proposed bridge it is vital to evaluate the safety of the ship and the bridge. In this paper, detailed finite element models of a cruise ship and a steel box girder are developed. The impact scenarios and structural damages are studied. The results show that the proposed bridge girder design is generally safe to resist normal accidental ship collision loads. Numerical model of the whole bridge is also developed for further study of bridge global response subjected to ship collision load.


2014 ◽  
Vol 136 (4) ◽  
Author(s):  
M. R. Emami Azadi

In the present study, the influence of ship collision parameters related to vessel impact energy and also the impact scenario on the global nonlinear dynamic behavior of a three-leg jack-up platform is investigated. A North-Sea three-leg jack-up platform is studied as a case which is located in water depth of about 105 m. Nonlinear elastoplastic and hyperelastic type spring models are used for ship bow and broad-side impacts. A nonlinear elastoplastic type spud-can-soil interaction model is also applied. Loose sand to medium dense sand profile is considered at the sea-base. The effects of ship collision parameters such as ship mass and velocity, impact direction, hit point on jack-up as well as the spud-can-soil interaction are studied. For the first time, the supply vessel impact energy level far beyond 14 MJ as conventionally applied for ship-jack-up leg collision analysis (i.e., higher energy impact) has been also considered. The findings of this study indicated that the type of bow or broad-side impact as well as the spud-can-soil interaction may have considerable effects on the nonlinear dynamic behavior of the jack-up platform during ship collision. It is also found that ship collision in the direction of incident waves with mass of 5000 tons and impact velocity of 5 m/s displacement may have more profound effect on global dynamic response of the jack-up platform near ultimate collapse. It is also found in this research work that dynamic postimpact behavior of the jack-up platform may be greatly influenced by the combined action of extreme wave and current.


2007 ◽  
Vol 27 (First Serie (1) ◽  
pp. 81-97
Author(s):  
David Newlands ◽  
Alexandra Brehme
Keyword(s):  

2019 ◽  
Vol 58 (2) ◽  
pp. 315-337 ◽  
Author(s):  
Thomas Cogswell

AbstractHistorians have not paid close attention to the activities of freebooters operating out of Dunkirk in the late 1620s. This essay corrects that omission by first studying the threat from Dunkirk to England's east coast and then addressing how the central government, counties, and coastal towns responded. A surprisingly rich vein of manuscript material from Great Yarmouth and particularly from the Suffolk fishing community of Aldeburgh informs this case study of the impact of this conflict around the North Sea.


2021 ◽  
Vol 9 (2) ◽  
pp. 180
Author(s):  
Lei Du ◽  
Osiris A. Valdez Banda ◽  
Floris Goerlandt ◽  
Pentti Kujala ◽  
Weibin Zhang

Ship collision is the most common type of accident in the Northern Baltic Sea, posing a risk to the safety of maritime transportation. Near miss detection from automatic identification system (AIS) data provides insight into maritime transportation safety. Collision risk always triggers a ship to maneuver for safe passing. Some frenetic rudder actions occur at the last moment before ship collision. However, the relationship between ship behavior and collision risk is not fully clarified. Therefore, this work proposes a novel method to improve near miss detection by analyzing ship behavior characteristic during the encounter process. The impact from the ship attributes (including ship size, type, and maneuverability), perceived risk of a navigator, traffic complexity, and traffic rule are considered to obtain insights into the ship behavior. The risk severity of the detected near miss is further quantified into four levels. This proposed method is then applied to traffic data from the Northern Baltic Sea. The promising results of near miss detection and the model validity test suggest that this work contributes to the development of preventive measures in maritime management to enhance to navigational safety, such as setting a precautionary area in the hotspot areas. Several advantages and limitations of the presented method for near miss detection are discussed.


1975 ◽  
Vol 10 (4) ◽  
pp. 621-632 ◽  
Author(s):  
P. W. McMillan ◽  
J. R. Tesh

2008 ◽  
Vol 45 (02) ◽  
pp. 77-88
Author(s):  
Erlend Hovland

Simplified technical and economical analysis of a total of 12 different ship designs has been performed and compared with operational profiles of typical North Sea Diving and Construction vessels. Evaluation of what impact changes to the operational profile has on the best-suited vessel for the operation has also been performed. The paper focuses on optimizing the design to achieve a maximum of days in operation working day. Nomenclature


2016 ◽  
Vol 13 (3) ◽  
pp. 841-863 ◽  
Author(s):  
H. Brenner ◽  
U. Braeckman ◽  
M. Le Guitton ◽  
F. J. R. Meysman

Abstract. It has been previously proposed that alkalinity release from sediments can play an important role in the carbonate dynamics on continental shelves, lowering the pCO2 of seawater and hence increasing the CO2 uptake from the atmosphere. To test this hypothesis, sedimentary alkalinity generation was quantified within cohesive and permeable sediments across the North Sea during two cruises in September 2011 (basin-wide) and June 2012 (Dutch coastal zone). Benthic fluxes of oxygen (O2), alkalinity (AT) and dissolved inorganic carbon (DIC) were determined using shipboard closed sediment incubations. Our results show that sediments can form an important source of alkalinity for the overlying water, particularly in the shallow southern North Sea, where high AT and DIC fluxes were recorded in near-shore sediments of the Belgian, Dutch and German coastal zone. In contrast, fluxes of AT and DIC are substantially lower in the deeper, seasonally stratified, northern part of the North Sea. Based on the data collected, we performed a model analysis to constrain the main pathways of alkalinity generation in the sediment, and to quantify how sedimentary alkalinity drives atmospheric CO2 uptake in the southern North Sea. Overall, our results show that sedimentary alkalinity generation should be regarded as a key component in the CO2 dynamics of shallow coastal systems.


Sign in / Sign up

Export Citation Format

Share Document