Ship Impact Research Articles

Overview of Structural Life Assessment and Reliability, Part III: Impact, Grounding, and Reliability of Ships under Extreme Loading

Overview of Structural Life Assessment and Reliability, Part III: Impact, Grounding, and Reliability of Ships under Extreme Loading

Overview of Structural Life Assessment and Reliability, Part III: Impact, Grounding, and Reliability of Ships under Extreme Loading

Overview of Structural Life Assessment and Reliability, Part III: Impact, Grounding, and Reliability of Ships under Extreme Loading

Optimization and application of a crashworthy device for the monopile offshore wind turbine against ship impact

The risk of offshore wind turbines collision with ships is on the rise during the service period with the increase of offshore wind farms and ship routings. In order to minimize the damage of offshore wind turbines caused by ship impact, a crashworthy device, which contains a rubber blanket and outer steel shell, is proposed. The rubber hardness and the rubber and steel shell thicknesses of the crashworthy device are optimized by comparing the collision-force and nacelle acceleration using LS-DYNA explicit code. The main reason for lessening the maximum collision-force and nacelle acceleration is that the rubber blanket could absorb a portion of ship energy by using its own structure deformation. Therefore, an optimal crashworthy device for the monopile offshore wind turbine, meeting the weight constraint, is suggested and implemented in various impact scenarios. The obvious effects of crashworthy devices are a decrease of the maximum collision-force and nacelle acceleration, especially for ships with smaller initial kinetic energy. The damage area of plastic strain for foundations is reduced to zero when crashworthy devices are used in the analysis scenarios. This paper may be useful in anti-impact design of offshore wind turbines.

Study on the Lateral Deformation of the Flexible Berthing Pile of High-Pile Wharf under Ship Impact Load

Flexible berthing pile-high pile wharf is a system which is composed of flexible berthing pile, rubber fender and pile platform. The system was divided into two forms based on the pile platform sustained the impact load or not. The method to analysis the lateral deformation of the pile was relatively mature when the platform was subjected to the impact load. Instead, when the pile platform is subjected to the impact load, the analytical method is unsatisfactory because of the complexity about the lateral deformation of the system. This paper takes the second condition as the research object, and study the lateral deformation of the pile, rubber fender and the pile platform. The mathematical formula is built on the horizontal force balancing condition and displacement coordination at the top of pile, the method to evaluate the correlation coefficients of the formulas is suggested, and the steps that solve the formulas by iterative method are described. The theory is clear, and the result can offer a reference for structure design and code revision.

Air quality monitoring in communities of the Canadian Arctic during the high shipping season with a focus on local and marine pollution

Abstract. The Canadian Arctic has experienced decreasing sea ice extent and increasing shipping activity in recent decades. While there are economic incentives to develop resources in the north, there are environmental concerns that increasing marine traffic will contribute to declining air quality in northern communities. In an effort to characterize the relative impact of shipping on air quality in the north, two monitoring stations have been installed in Cape Dorset and Resolute, Nunavut, and have been operational since 1 June 2013. The impact of shipping and other sources of emissions on NOx, O3, SO2, BC, and PM2.5 pollution have been characterized for the 2013 shipping season from 1 June to 1 November. In addition, a high-resolution Air Quality Health Index (AQHI) for both sites was computed. Shipping consistently increased O3 mixing ratio and PM2.5 concentration. The 90% confidence interval for mean difference in O3 mixing ratio between ship- and no ship-influenced air masses were up to 4.6–4.7 ppb and 2.5–2.7 ppb for Cape Dorset and Resolute, respectively. The same intervals for PM2.5 concentrations were up to 1.8–1.9 μg m−3 and 0.5–0.6 μg m−3. Ship-influenced air masses consistently exhibited an increase of 0.1 to 0.3 in the high-resolution AQHI compared to no ship-influenced air masses. Trajectory cluster analysis in combination with ship traffic tracking provided an estimated range for percent ship contribution to NOx, O3, SO2, and PM2.5 that were 12.9–17.5 %, 16.2–18.1 %, 16.9–18.3 %, and 19.5–31.7 % for Cape Dorset and 1.0–7.2 %, 2.9–4.8 %, 5.5–10.0 %, and 6.5–7.2 % for Resolute during the 2013 shipping season. Additional measurements in Resolute suggested that percent ship contribution to black carbon was 4.3–9.8 % and that black carbon constituted 1.3–9.7 % of total PM2.5 mass in ship plumes. Continued air quality monitoring in the above sites for future shipping seasons will improve the statistics in our analysis and characterize repeating seasonal patterns in air quality due to shipping, local pollution, and long-range transport.

Ship impact model for technical assessment and selection of Carbon dioxide Reducing Technologies (CRTs)

It is not unreasonable to imagine that the future may herald higher energy prices and greater regulation of shipping׳s Greenhouse Gas (GHG) emissions. With the introduction of the Energy Efficiency Design Index (EEDI) into MARPOL Annex VI, tools are needed to assist Naval Architects and Marine Engineers to select the best solutions to meet evolving requirements for reduced fuel consumption and associated carbon dioxide emissions. To that end, a concept design tool, the Ship Impact Model (SIM), has been developed for quickly calculating the technical performance of a vessel with one or more Carbon dioxide Reducing Technologies (CRTs) at an early design stage. The underlying basis for this model is the calculation of changes from known ‘baseline ships’. The Ship Impact Model has been used in two projects to assess which selection (individual or combination) of Carbon dioxide Reducing Technologies (CRTs) have the most potential, in terms of cost-effectiveness and under other technical, operational and regulatory influences.

THE ANALYSIS OF EFFECTIVE ENERGY OF SHIP’S BERTHING TO THE QUAY

The berthing of ship to the quay is last stage of navigation process. An ideal manoeuvre would be consisted in a total loss of speed at the moment the ship makes contact with the quay. In practice, the ship has some speed, which caused the impact of ship in the quay. The accident can be happened when kinetic energy overdone the admissible value during contact the ship-quay. In results, the damage of ship’s hull or port structure can occur. The fenders improve the safety of berthing operations by partially absorbing the kinetic energy of ship. The fenders parameters should be properly selected relative to existing condition during ship’s berthing. It depends on effective energy of berthing ship. There are used some method to calculate of its value. One of them is based on phenomena of ship turning relative to point of first contact to the quay. Then the part of ship’s kinetic energy is altered to work of turn, and in result, energy of ship impact is decreased. This part can be determined by coefficient of eccentricy. Its value mainly depends on radius of ship’s turning, which is equal of distance between point of ship, gravity and point of first contact with quay. Simplified method of calculation the eccentricy coefficient based on ships angle of approaching to the quay. But such estimated value is weighted some discrepancy. The paper presents the analysis of methods of calculation the kinetic energy during first impact in the quay. Especially, the geometrical shape of ship’s hull is considered to achieve the accuracy value of ship’s impact energy during the berthing to the quay. The application of elaborated method permits to optimize the parameters of fender system.

A study on ship impacting a flexible crashworthy device for protecting bridge pier

As the accident of a vessel impacting a bridge pier will cause serious disaster, such as destroyed bridge, sinking ship and polluting environment, the technology and method to protect bridge pier from ship collision have been widely investigated recently. Due to the huge kinetic energy of large-tonnage ship and the short time duration in the collision, the studies involve impact mechanics. A developed flexible crashworthy device has been developed to protect bridges, which consists of an outer steel-periphery, an inner steel-periphery and the rubber coating SWRCs(soft elements) installed between them. When the SWRC crashworthy device is installed, the collision duration under low impact force is prolonged due to its high compliance, which results in the ship having enough time to turn its navigation direction and most of the remainder kinetic energy being carried off by the turned away ship. Consequently, both impact forces on the ship and on the bridge pier decrease markedly. This is the key reason as to why the SWRC crashworthy device can avoid the destruction of both the bridge and the ship. Based on our results of theoretical studies and numerical simulations, the present paper will propose an experiment-adopted a real ship to impact a flexible crashworthy device. The collision test has been performed 12 times with different speed, carrying capacity, and impact angle of the ship. After the experiments, the ship, flexible crashworthy device and the pier are not damaged. The experiments show that the flexible crashworthy device can turn away the impact ship, so that the ship moves along the outer part of the device, which reduces the ship impact force on the bridge pier obviously. It not only protects bridges but also avoids the damage to ships.

“SHORE TO SHIP” SYSTEM – AN ALTERNATIVE ELECTRIC POWER SUPPLY IN PORT

Greater interdependence and integration among the countries worldwide have resulted in the growth of the world trade and, what follows, marine transportation. In the last few years, despite the world economic stagnation, the number of ships has increased. An increase in the marine transportation means greater air pollution caused by ships, what is of paramount importance for the port cities. One of the efficient ways of limiting the negative impact of ships lying in ports on the environment is the power supply from the local electricity stations. This will allow for turning marine power generating systems off, what will result in the emission elimination in the ship’s mooring time along with the decrease of noise and vibrations. The infrastructure of the port electric installation necessary for the ships’ supply has to be designed so as to make the operating of different ship types possible. It is complicated as all over the world ships are equipped with different electric systems. The paper deals with general issues related to common nominal voltages and frequencies for vessels which call in European harbours and their estimated power demands. Additionally, a case study of a ferry vessel, currently undergoing retrofitting for shore connections, is presented and some particulars concerning technical solutions and environmental profits are described.

Numerical simulation of the propagation of ship-induced Riemann waves of depression into the Venice Lagoon

Large in situ measured ship-induced depression waves (Bernoulli wakes) in the Malamocco-Marghera industrial channel of the Venice Lagoon are interpreted as long-living strongly nonlinear Riemann (simple) waves of depression. The properties of these depressions are numerically replicated using nonlinear shallow water theory and the CLAWPACK software. The further behaviour of measured depressions is analysed by means of replicating the vessel-induced disturbances with the propagation of initially smooth free waves. It is demonstrated that vessel-driven depressions of substantial height (> 0.3 m) often propagate for more than 1 km from the navigation channel into areas of the lagoon of approximately 2 m water depth. As a depression wave propagates into the lagoon, its front slope becomes gradually less steep, but the rear slope preserves an extremely steep bore-like appearance and the amplitude becomes almost independent of the initial properties of the disturbance. Analysis suggests that even modest ships in terms of their size, sailing speed, and blocking coefficient may generate deep depressions that travel as compact and steep entities resembling asymmetric solitary waves over substantial distances into shallow water adjacent to navigation channels. Their impact may substantially increase the environmental impact of ship wakes in this and similar water bodies.

Evaluation on Risk for Ship Collision with Archbridge and Crash Capability of Anti-Collision

The development of the highway traffic has promoted the construction of increasing numbers of river-crossing bridges, but at the same time, large-size ship causes serious threat to structural safety of the bridge. The probability of bridge-ship collision increases, water safety accidents have happened frequently in the recent years. Arch bridge is easier to be subjected to the threat of ship collision because of small navigation clearance on both sides. However, study on the destructive consequences by ship impact on arch bridge is seldom. This paper takes reinforced concrete arch bridge as an example, on the basis of the forecast of the water-level frequency, flow velocity and long-term navigation density of the ship, the ship collision probability on different parts of the arch ring at different water levels are analyzed to deduce the annual collapse frequency of the grand bridge. The risk matrix evaluation result shows that there is medium risk in long-term. The establishment of finite element numerical model concludes the energy absorption and the change process when the arch ring suffers from collision from the ship under different working conditions as well as the relationship among the impact force, crown displacement and collision depth along with time change. According to the result of simulated analysis, the maximum collision force of the main arch ring suffered from the ship is 25.9MN, and the resistance of the main arch ring is 33.6 MN, so the existing structure basically meets the requirement for fortification against the ship collision. The numerical simulation results are qualitatively consistent with the risk of evaluation. The results of the analysis can provide scientific foundation to the maintenance and management of the arch bridge.

Three dimensional modeling of laterally loaded pile groups resting in sand

Many structures often carry lateral loads due to earth pressure, wind, earthquakes, wave action and ship impact. The accurate predictions of the load–displacement response of the pile group as well as the straining actions are needed for a safe and economic design. Most research focused on the behavior of laterally loaded single piles though piles are most frequently used in groups. Soil is modeled as an elastic-perfectly plastic model using the Mohr–Coulomb constitutive model. The three-dimensional Plaxis model is validated using load–displacement results from centrifuge tests of laterally loaded piles embedded in sand. This study utilizes three dimensional finite element modeling to better understand the main parameters that affect the response of laterally loaded pile groups (2×2 and 3×3 pile configurations) including sand relative density, pile spacing (s=2.5 D, 5 D and 8 D) and pile location within the group. The fixity of the pile head affects its load–displacement under lateral loading. Typically, the pile head may be unrestrained (free) head as the pile head is allowed to rotate, or restrained (fixed) head condition where no pile head rotation is permitted. The analyses were performed for both free and fixed head conditions.

Research Note: An Analysis of Cruise Ship Impact on Local Hotel Demand — An Event Study in Charleston, South Carolina

This study examines cruise passenger demand for hotel accommodation in Charleston, South Carolina, prior to embarkation and after debarkation. The findings reveal that cruise passengers are significant drivers of room night demand around embarkation and debarkation. In addition, cruise passenger demand for room nights was not isolated to non-tourist districts of the greater metropolitan area, suggesting that a cruise from Charleston was coupled with a short vacation. This research is particularly important to destination managers, port authorities, municipalities and other stakeholders as they examine and negotiate the frequency, type and timing of passenger cruise service that provides the most positive benefit for the community.

Numerical simulation and analytical modeling of pile-supported structures subjected to ship collisions including soil–structure interaction

Most of the pile-supported protection structures were designed by empirical and static analyses to resist ship impact loading. Limited studies were carried out to reveal the failure modes and the dynamic interaction process of the pile-supported structures subjected to ship collisions. To clarify these issues, high-resolution finite element models of the ship–structure–soil interactions are developed in this paper. Several modeling issues (e.g., material model, artificial boundary and stress initialization) are discussed herein to ensure the rationality of the numerical models. Numerical simulations indicate that the platform and the connection of the protective system should be carefully designed to prevent their brittle failure besides providing the piles with enough ductility. Four interaction phases (i.e., initial contact, loading with approximate velocities, unloading and free vibration) are clearly identified for the overall flexural failure of the pile-supported structures. To efficiently predict the collision-induced responses, an analytical model with two-degree-of-freedom is proposed based on the high-resolution simulation observations. Methods of determining the equivalent mass and the force–deformation relationship involved in the analytical model are discussed in detail. The dynamic responses obtained from the analytical model are compared with the high-resolution FE results. It is found that the proposed simplified model is reasonable and efficient.

Terrorism Risks for Bridges in a Multi-Hazard Environment

The paper will assess terrorist threats to new and existing bridges and the cost-effectiveness of protective counter-terrorism measures. This analysis will consider threat likelihood, cost of security measures, risk reduction and expected losses to compare the costs and benefits of protective measures to bridges to decide which protective measures are cost-effective. In this paper, a break-even cost-benefit analysis determines the minimum probability of an attack, absent the protective measures, that is required for the benefit of the protective measures to equal their cost for new and existing bridges. It was found that unless terrorist threat probabilities are high, then typical protective measures are not cost-effective. Bridges and other critical infrastructure are subject to a range of natural and man-made hazards, and terrorism is most likely not as important a threat as natural hazards. It was found that economic risks to bridges from floods, earthquakes, and ship impact are higher than threats from terrorism.

Numerical simulation for progressive collapse of continuous girder bridge subjected to ship impact

The three-stage simulation method based on LS-DYNA was introduced in this study to simulate the progressive collapse of a continuous girder bridge after a ship-bridge collision. The pile-soil dynamic interaction and the initial stress and deformation of the whole bridge before the collision were considered. By analyzing the damage, deformation, stress distribution and collapse process of the whole bridge, the results show that the displacement response of the cap beam lags behind the pile cap. The response order of the whole bridge’s components depends on their distances from the collision region. The plastic deformation of soil around piles has a positive effect on delaying the further increase in the displacement of piles. The impacted pier’s losing stability and its superstructure’s excessive deformation are the main reasons leading to the progressive collapse of the continuous girder bridge.

Dynamics of steel offshore platforms under ship impact

This paper deals with the prediction of the dynamic response of steel offshore platforms to high energy impacts from typical supply vessels. The contribution of the high modes of a cantilever beam type structure with a concentrated top mass subjected to transverse impact from rigid and deformable strikers is analysed. A procedure to develop simplified equivalent systems for efficient structural response analysis is presented and its reliability tested by comparing the results from the explicit non-linear FE simulations. Effects such as the overall rotation of the installation, plastic deformations in the contact area, different impact locations and different hinge mechanisms are taken into account. It is shown that the use of the proposed equivalent systems with a reduced number of DOF's can provide accurate results at significantly less computational efforts as compared to the FE simulations. The derivation of some parameters of the equivalent dynamic elastic–plastic SDOF/2SDOF systems, however, needs to consider the complexity of the analysed steel frames and perform preliminary non-linear static analyses. Therefore, further studies of different impact scenarios on platforms with different configurations are recommended to augment the results presented here.

Reduction of Underwater Radiated Noise from Ships: New Shipbuilding Challenge. The Vessels "Ramón Margalef" and "Ángeles Alvariño" as Technological References of How to Build Silent Vessels

Abatement of noise radiated by all kinds of vessels, and specially Underwater-Radiated Noise, because of its impacton marine life, has become the most outstanding novelty and the most dificult challenge the shipbuilding industryhas ever faced. Hence, the industry seeks to other new solutions to comply with the new guidelines and requirementsthat have been recently introduced and promoted by the EU, marine institutions, and the scientific community. "isnew topic, already studied and solved by the navies because of their strategic requirements, is now in the limelight andall the different aspects are being studied and discussed among the different players mentioned. In this new trend, theappearance of some class notations with “different limits”, assertions such as that the “propeller” is the major noise source,and the absence of consensus among the biological community about what should be the limits (for not affecting marine fauna), it is difficult to define the technological steps that should be followed. Until a consistent agreement is reached, the shipbuilding industry and the naval engineers will be “fighting against a ghost”. Within this “confusing scenario”, this paper is a clear example of how the Spanish shipbuilding industry is moving ahead to reduce the impact of new ships. The dynamic and acoustic design, developed by the authors, of the fishing research vessels “Ramón Margalef” and “Ángeles Alvariño” for the Oceanographic Spanish Institute and the experimental results obtained, in full compliance with ICES N°209 Underwater-Radiated Noise requirements, makes them reference vessels for the construction of “Silent Vessels”.

Canary Wharf Crossrail station cofferdam, London, UK: design, construction and performance

The construction of the first Crossrail station at Canary Wharf in London, UK reached a significant milestone in March 2012 when the station box was formally handed over to Crossrail for the preparation of the tunnel eyes to receive and re-launch the tunnel-boring machine. The station box is constructed in the North Dock at Canary Wharf in around 9 m of dock water. Excavation of the 265 m long, 25–30 m wide and 18 m deep station box was completed in about 12 months. This paper provides useful guidance for practising engineers on the design and construction of cofferdams' retaining walls in a dock environment. It describes the performance of the retaining structures constructed using the innovative Japanese Giken tubular pile system. Some details are also included of the site-wide dewatering undertaken to lower the groundwater in the Chalk and control it, allowing excavation into the Upnor Formation and Thanet Sand. The effects of unexploded ordnance probing on the performance of the retaining wall are described. Together with details of the laboratory tests undertaken to inform the ship impact berm design and the monitoring system used to verify the retaining wall design and comparison of the predicted and measured wall movements during excavation.

Numerical analysis of ship–bridge collision's influences on the running safety of moving rail train

This paper investigates the ship–bridge collision process and its influences on the running safety of the moving light rail train. Taking a long span cable-stayed bridge across the Huangpu River as example, the 3-D dynamic model of train-bridge coupled system subjected to ship impact was studied with the aid of the finite element analysis (FEA) code LS-DYNA 971. The bridge model and the coupled rigid–flexible multi-body train model were coupled through non-linear wheel–rail interface, and the coupled dynamic model was solved using mixed time explicit integration approach. By studying the effects of train speed and the momentum of impacting ship on the running safety of the rail train, the relationship between the maximum safety speed of the train and the momentum of the impacting ship is predicted, that is, the maximum allowable train speed decreases with the increase of the momentum of the impacting ship. The mixed time integration method could speed up the calculation process for crashworthiness analysis with great differences in element sizes at different parts of model.