References of "Richir, Thomas"
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See detailMulticriterion Scantling Optimization of the Midship Section of a Passenger Vessel considering IACS Requirements
Richir, Thomas; Caprace, Jean-David ULg; Losseau, Nicolas ULg et al

in The 10th International Symposium on Practical Design of Ships and Other Floating Structures (PRADS) (2007, October)

In the scantling design of a passenger ship, minimum production cost, minimum weight and maximum moment of inertia (stiffness) are conflicting objectives. For that purpose, recent improvements were made ... [more ▼]

In the scantling design of a passenger ship, minimum production cost, minimum weight and maximum moment of inertia (stiffness) are conflicting objectives. For that purpose, recent improvements were made to the LBR-5 software (French acronym of “Stiffened Panels Software”, version 5.0) to optimize the scantling of ship sections by considering production cost, weight and moment of inertia in the optimization objective function. Moreover, IACS requirements regarding bending, shearing and buckling strength are currently available in LBR-5. Until now, only raw scantling optimizations were performed with LBR-5. Thanks to new developments using heuristics, it is now possible to realize discrete optimization so that a standardized and “ready to use” set of optimum scantlings can be obtained. [less ▲]

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See detailLeast Cost Optimization of Large Passenger Vessels
Richir, Thomas; Caprace, Jean-David ULg; Losseau, Nicolas ULg et al

in Ships & Offshore Structures (2007), 2

The LBR-5 software allows optimizing ship structures according to objectives of higher inertia, less weight and/or lower cost. This last criterion offers the choice between two approaches of calculation ... [more ▼]

The LBR-5 software allows optimizing ship structures according to objectives of higher inertia, less weight and/or lower cost. This last criterion offers the choice between two approaches of calculation. The first approach is based on a simplified assessment of the cost in which the total cost is described by rather simple analytical functions which bring into play on the one hand the design variables and on the other hand empirical parameters. In the second approach, the calculation of the cost is based on data specific to the shipyard. The material cost is analyzed according to the first approach while the cost of the labor considers each relevant operation of the ship building with respect to the LBR-5 model. A survey of all the tasks was carried out at Aker Yards France, and a thorough study made it possible to develop assessment tools of the labor cost for each operation as functions of the design variables. Plate straightening operations are also considered in this analysis. This paper presents a cost-based optimization study carried out on a large passenger ship structure with more than 600 design variables, by the use of the detailed approach for the cost calculation. The structural model has been formulated on the basis of technical documentation prepared by Aker Yards France. The loads and strength criteria applied on the model are considered according to classification society rules (Bureau Veritas). Results and conclusions of the study are presented. [less ▲]

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See detailA mixed-integer heuristic for the structural optimization of a cruise ship
Bay, Maud ULg; Crama, Yves ULg; Richir, Thomas et al

in COMPIT 2007 , Cortona, Italy (2007, April 23)

A heuristic approach is proposed to solve the structural optimization problem of a cruise ship. The challenge of optimization is to define the scantling of the structure of a ship in order to minimize the ... [more ▼]

A heuristic approach is proposed to solve the structural optimization problem of a cruise ship. The challenge of optimization is to define the scantling of the structure of a ship in order to minimize the weight or the production cost. The variables are the dimensions and positions of the constitutive elements of the structure: they are discrete by nature. The objective functions are nonlinear functions. The structure is submitted to geometric constraints and to structural constraints. The geometric constraints are linear functions and the structural constraints are implicit functions requiring a high computation cost. The problem belongs to the class of mixed-integer nonlinear problems (MINLP). A local heuristic of the type “dive and fix” is combined with a solver based on approximation methods. The solver is used as a black-box tool to perform the structural analysis and solve the nonlinear optimization problems (NLP) defined by the heuristic. The heuristic is designed to always provide a discrete feasible solution. Experiments on a real-size structure demonstrate that the optimal value of the mixed-integer problem is of the same magnitude as the optimal value of the optimization problem for which all the variables can take continuous values. [less ▲]

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See detailLeast cost optimization of a large passenger vessel
Richir, Thomas; Losseau, Nicolas; Pircalabu, Eugen et al

in International Conference on “Advancements in Marine Structures”, (Proceedings of MARSTRUCT’2007), Edt Guedes Soares & Das, Publ: Taylor & Francis Group, UK, 12-14 March 2007 (2007, March)

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See detailAssessment of Ultimate Bending Moment of Ships from a Reliability Point of View, Using Independent Perturbations Method
Toderan, Catalin; Richir, Thomas; Caprace, Jean-David ULg et al

in Network for Integrating Structural Safety, Risk and Reliability (ASRANet) (2006, July)

This paper presents a method to asses hull girder ultimate bending moment distribution, taking into account parameters uncertainty. This method is a part of a research activity carried out at University ... [more ▼]

This paper presents a method to asses hull girder ultimate bending moment distribution, taking into account parameters uncertainty. This method is a part of a research activity carried out at University of Liege. The method is able to compute four statistical moments of ultimate strength distribution: average, standard deviation, skewness and kurtosis. Geometry parameters, material parameters and initial imperfections (initial deflections and residual stresses) are considered as random variables and a distribution is associated to each of them. Ultimate bending moment algorithm is a progressive collapse analysis based on Smith method and associated with the load-end shortening model proposed by Bureau Veritas and Joint Bulker Project Rules (JBP). In order to perform a reliability analysis, this algorithm is coupled with independent perturbations method. The advantage is a lower number of simulations compared to the standard Monte-Carlo procedure and a good use of the initial information that is available. The paper contains also a comparative analysis between the presented method and a linear sensitivity analysis performed by the ISSC 2000 “Ultimate Strength” committee for a VLCC structure. [less ▲]

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See detailUltimate Strength of Stiffened Panels Assessment Taking Into Account Model Uncertainty
Toderan, Catalin; Richir, Thomas; Caprace, Jean-David ULg et al

in Proceedings of OMAE2006 (2006, June 04)

This paper presents a methodology to take into account model uncertainties related to the load-end shortening curve of stiffened panels. This method is a part of a research activity carried out at ... [more ▼]

This paper presents a methodology to take into account model uncertainties related to the load-end shortening curve of stiffened panels. This method is a part of a research activity carried out at University of Liège. His goal is to propose a reliability based model to assess hull girder ultimate strength using a progressive collapse algorithm. The numerical results presented here concern the load-shortening model chosen for this research, which is based on Bureau Veritas rules. Model uncertainty is quantified as a parameter considered as a random variable. Four statistical moments (mean, standard deviation, skewness and kurtosis) of this parameter are calculated and analyzed using a data-base of stiffened panels test results published in recent years. In order to increase the number of "actual" values for the statistical assessment, the data-base is completed with non-linear finite element analysis results. The paper contains also some recommendation for the implementation of the proposed method in ultimate strength reliability based analysis. [less ▲]

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See detailSIMULATION AND OPTIMIZATION OF A SHIPBUILING WORKSHOP
Bair, Frédéric ULg; Langer, Yves; Richir, Thomas et al

in ICCC Bexi Conference (2006, June)

This study concerns the simulation of a shipbuilding workshop, and its optimization to improve its productivity. Usually, simulation is used to improve efficiency but this optimization is often done ... [more ▼]

This study concerns the simulation of a shipbuilding workshop, and its optimization to improve its productivity. Usually, simulation is used to improve efficiency but this optimization is often done manually, particularly for shipbuilding workshop. This is due to the particularity of pieces to be manufactured: almost each of them is different and required thus particular operations. The automation is not so much present as, for example, in automotive industry. In spite of high CPU time for that kind of simulation, we will try to use optimization methods to improve productivity. Algorithm used is a genetic algorithm. [less ▲]

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See detailOptimization of a Rolling and Floating Lock Gate for the Port of Antwerp
Richir, Thomas; Pecket, J.-P.; Toderan, C. et al

in ICCC-ASCE: 2006, Int'l Conf. on Computing in Civil Engineering of ASCE, Joint International Conference on Computing and Decision Making in Civil and Building Engineering, Montreal, Canada, June 2006, Paper IC-23, pp155-163 (2006, June)

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See detailScantling Optimization of Double-Hull Structures to Minimize their Production Cost
Richir, Thomas; Karr, D.; Rigo, Philippe ULg

in IMDC 2006, Ann Arbor, Michigan, USA, May 2006 (2006, May)

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See detailDiscussion on Paper D04 “Ultimate limit state design technology for aluminium multi-hull ship structures, SNAME Transactions, Vol.113, (2005)”
Rigo, Philippe ULg; Richir, Thomas

in Ultimate limit state design technology for aluminium multi-hull ship structures, SNAME Transactions, Vol.113 (2005)

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See detailDifferential Equations of Stiffened Panels and Fourier Series Expansion
Rigo, Philippe ULg; Richir, Thomas

in The Annals of “Dunarea De Jos” University of Galati (2005) (2005)

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