Loïc Buldgen

Numerical crashworthiness analysis of an offshore wind turbine monopile impacted by a ship

The objective of the present work is to understand the crushing behavior of a predefined wind turbine jacket when it is impacted by a ship. To investigate the resulting deformation modes and the repartition of dissipated energy, nonlinear finite element analyses are performed to simulate both rigid and deformable ships colliding the jacket at different velocities. In a first part, a sensitivity analysis to the jacket impacted area is carried out to find the most damaging situation. Then, the influences of gravity loads, wind force, and soil stiffness are studied, considering that the striking ship is rigid. In a second part, the jacket is supposed to be collided by two different deformable vessels and the internal energy distribution between the jacket and the striking ships is analyzed for different jacket leg thicknesses. Some numerical analyses focus also on the transfer of the crushing force between the impacted leg to the others through the braces. All these numerical results will further serve to fix the hypotheses for the development of a simplified tool based on analytical formulations.

Simplified Analytical Method for Estimating the Resistance of Lock Gates to Ship Impacts

The present paper is concerned with the design of lock gates submitted to ship impacts. In this paper, a simplified analytical method is presented to evaluate the resistance of such structures under collision. The basic idea is to assume that the resistance is first provided through a local deforming mode, corresponding to a localized crushing of some impacted structural elements. For consecutive larger deformations, the resistance is then mostly provided through a global deforming mode, corresponding to an overall movement of the entire gate. For assessing the resistance in the case of the local deforming mode, the structure is divided into a given number of large structural entities called “superelements.” For each of them, a relation between the resistance of the gate and the penetration of the striking ship is established. However, as some results are already available in the literature, this subject is not treated extensively in this paper. On the contrary, the calculation of the resistance of the gate provided through the global mode is detailed and the strategy to switch from local to global deformation is highlighted. Finally, we propose to validate our developments by making a comparison between results obtained numerically and those predicted by the present analytical approach.

Fast strength assessment of mitre gates to ship impact

The present paper is concerned with the design of lock mitre gates submitted to ship impacts. A simplified analytical method is presented to evaluate the resistance of such structures under collision. The basic idea is to assume that the resistance is first provided through a local deforming mode, corresponding to a localised crushing of some impacted structural elements. For consecutive larger deformations, the resistance is then mostly provided through a global deforming mode corresponding to an overall movement of the entire gate. The developments are validated by comparing results obtained numerically to those predicted by the developed analytical approach for mitre gates.

A review of technical solutions and simulation approaches for ship collisions with lock gates

Abstract Lock gates are frequently found at inland waterway locks and sea navigation locks. Entering a lock with a ship is a challenging manoeuvre, which can potentially lead to the ship colliding with the lock gate. Such collision may permanently damage the gate causing the lock operation to be disrupted and the ship transport to be delayed. Consequently, it is important to design for the possibility of a ship colliding with the lock gate to ensure its operability as well as the safety of the operation. In order to do so, a variety of recommendations and standards exist, which are however neither unified nor require the assessment of the lock under a ship collision on a mandatory basis. Therefore, this paper presents the current developments in assessment approaches for ship collisions with lock gates as well as current gate protection practices. The paper concludes with a recommendation of assessment approaches, which can be used to identify safe lock gate approach velocities in the case of existing locks or collision resistant structural layouts for new buildings of lock facilities.

A Simplified Procedure to Assess the Strength of a Ship Impacting a Lock Mitered Gate

This paper presents a simplified procedure allowing for a rapid prediction of the strength of a lock mitered gate s ubmitted to a ship impact. In this article, the force opposed to the penetration of the vessel is derived by supposing that the bow is perfectly rigid, so the total initial kinetic energy has to b e entirely transformed through an internal dissipation. For a given penetration of the striking vessel, an analytical p rocedure is followed in order to estimate the amount of energy dissipated by local and global deformations of the impacted st ructure. An equivalent quasi-static force is then derived. A co mparison is made with a finite elements simulation in order to test the analytical procedure.

Optimisation of Ship and Offshore Structures and Effective Waterway Infrastructures to Support the Global Economic Growth of a Country/Region

This paper includes the following parts:• Ship Structure Optimization: methodology to perform ship scantling optimization, decreasing steel weight and keeping the production cost at an acceptable level. We first review the links between “Design” and “Optimization” and secondly define the place of “Ship Structure Optimization” within the general framework of a “Ship Optimization”.• Ship impacts (Collision), with applications to navigation lock and dry dock gates: these gates have to be designed taking into account accidental loads, such as ship collisions. A new simplified analytical method is proposed, based on the so-called super-element method. This method was developed to rapidly assess the crashworthiness of the collided structure and avoid high computational effort of numerical simulations.• Inland waterway Navigation and the development in South America of Inland Waterway Classifications.• EMSHIP, European ERASMUS MUNDUS education program (www.emship.eu): the unique master’s degree in Ship & Offshore Structures awarded by the prestigious European Erasmus Mundus Program. EMSHIP shares the outstanding experiences of educators, trainers, industrial partners and students in the rapidly developing areas of marine and offshore engineering industry.

Simplified analytical methods to analyze lock gates submitted to ship collisions and earthquakes

Abstract This paper presents two simplified analytical methods to analyze lock gates submitted to two different accidental loads. The case of an impact involving a vessel is first investigated. In this situation, the resistance of the struck gate is evaluated by assuming a local and a global deforming mode. The super-element method is used in the first case, while an equivalent beam model is simultaneously introduced to capture the overall bending motion of the structure. The second accidental load considered in this paper is the seismic action, for which an analytical method is presented to evaluate the total hydrodynamic pressure applied on a lock gate during an earthquake, due account being taken of the fluid-structure interaction. For each of these two actions, numerical validations are presented and the analytical results are compared to finite-element solutions.