The Experts below are selected from a list of 402 Experts worldwide ranked by ideXlab platform
Mehmet Polat Saka - One of the best experts on this subject based on the ideXlab platform.
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an improved particle swarm optimizer for steel grillage systems
Structural Engineering and Mechanics, 2013Co-Authors: Ferhat Erdal, Erkan Doğan, Mehmet Polat SakaAbstract:In this paper, an improved version of particle swarm optimization based optimum design algorithm (IPSO) is presented for the steel grillage systems. The optimum design problem is formulated considering the provisions of American Institute of Steel Construction concerning Load and Resistance Factor Design. The optimum design algorithm selects the appropriate W-sections for the beams of the grillage system such that the design constraints are satisfied and the grillage weight is the minimum. When an improved version of the technique is extended to be implemented, the related results and convergence performance prove to be better than the simple particle swarm optimization algorithm and some other meta- heuristic optimization techniques. The efficiency of different inertia weight parameters of the proposed algorithm is also numerically investigated considering a number of numerical grillage system examples.
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optimum spacing design of grillage systems using a genetic algorithm
Advances in Engineering Software, 2000Co-Authors: Mehmet Polat Saka, Ayse T. Daloglu, F MalhasAbstract:Abstract In this study a genetic algorithm based method is developed for the optimum design of grillage systems. The algorithm not only selects the optimum sections for the grillage elements from a set of standard universal beam sections, but also finds the optimum spacing required for the grillage system. Deflection limitations and allowable stress constraints are considered in the formulation of the design problem. Due to the fact that grillage elements are thin walled sections, warping plays an important role in their design, particularly, when they are subjected to significant torsional loading. The algorithm developed has the flexibility of including or excluding the effect of warping in the design process. Grillage structures are designed for uniformly distributed loading. The optimum spacings are determined both considering and not taking into account the effect of warping in the design. The comparison of the results shows that inclusion of warping in the design process has a significant effect on the optimum spacing.
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optimum design of grillage systems using genetic algorithms
Computer-aided Civil and Infrastructure Engineering, 1998Co-Authors: Mehmet Polat SakaAbstract:Genetic algorithms have attracted great attention due to their ability to provide a solution to discrete optimum design problems. In this study, a genetic algorithm is presented for the optimum design of grillage systems to decide the cross-sectional properties of members from a standard set of universal beam sections. The deflection limitations and the allowable stress constraints are considered in the formulation of the design problem. Furthermore, in obtaining the response of grillage systems, the effect of warping and shear is also taken into account. The algorithm starts with an initial population of designs and carries out basic genetic operations of selection, mating, crossover, and mutation that yield to a new generation. It continues the generation of populations until the same individual dominates the population. An improvement is also suggested to the general steps of the genetic algorithm to prevent the destruction of good individuals during the generation of new populations. The algorithm is applied to the optimum design of a 40-member grillage system to investigate the effect of warping.
Claude Daley - One of the best experts on this subject based on the ideXlab platform.
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evaluation of large structural Grillages subjected to ice loads in experimental and numerical analysis
Marine Structures, 2018Co-Authors: Claude DaleyAbstract:Abstract Laboratory-grown cone-shaped ice specimens (1 m diameter) were utilized to load large structural Grillages into a plastic response domain. The scantlings of the Grillages were typical of a transversely framed mid-body ice belt arrangement of a 10,000 ton Ice Class PC6 vessel. The maximum loads reached levels well beyond the elastic limit of the material and any acceptable plastic design point. The tests allowed for an evaluation of highly non-linear structural behavior and overload capacity considering the simultaneous failure of ice. Two separate large structural grillage tests were carried out with ice specimens loaded at a quasi-static loading rate (0.5 mm/s). The first set of tests were performed in two loading steps at identical loading positions at the mid-span of the central stiffener. The second set of tests were carried out in three loading steps at different loading positions along the span of the central stiffener of the grillage as a sequence of right-off, center, and left-off center. The experiments led to unique insight into the overload response and load carrying capacity of a large structural grillage as well as the effect of prior plastic damage on the structural behavior. Load-deflection curves and deformed shapes measured by MicroScribe® were compared with the results of nonlinear finite element (FE) analysis. The FE analysis results show a strong agreement with the physical experiments, which confirms that the nonlinear FE analysis is a suitable tool for the analysis of ice-strengthened ship structures subjected to extreme ice loading.
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controlled plastic deformation of a grillage using artificial freshwater ice at a large scale
22nd International Conference on Port and Ocean Engineering under Arctic Conditions (POAC'13)Federation of Finnish Learned SocietiesABSEspoo City of F, 2013Co-Authors: Mike Manuel, Claude Daley, Phani Suresh Reddy Gudimelta, Bruce ColbourneAbstract:This paper discusses the elastic and plastic stress and strain experienced by steel grillage structures during large-scale ice indentation tests undertaken in a laboratory setting. The work is part of the STePS2 (Sustainable Technology for Polar Ships and Structures) project, a 5-year engineering research project at Memorial University. The present work builds on previous experiments and is a part of a multi-stage project to investigate high-energy ice-structure collisions. The current experiments involve artificial glacial (freshwater) ice blocks loaded into a grillage representative of full-scale ship structure. The ice block is quasi-statically crushed against the grillage, and load and response data is recorded. Raw data is acquired through a network of strain gauges, and other instruments. The experiments are also recorded through several high-speed cameras. The work is unique in the scale of the tests, using realistic Grillages and ice blocks at forces and pressure loads representative of a real-world ship-ice interaction. During loading, the structural grillage undergoes extensive plastic deformation but displays tremendous overload capacity, much more than the material’s yield point, while demonstrating significant remaining reserve strength.
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realistic moving ice loads and ship structural response
The Twenty-second International Offshore and Polar Engineering Conference, 2012Co-Authors: Bruce W T Quinton, Claude Daley, Robert E. GagnonAbstract:Prior work by the authors has shown that moving ice loads incite a significantly different structural response in steel grillage structures than do stationary ice loads. The work was based on a validated explicit numerical model of a steel grillage. The main drawback was that the ice load model was largely unrealistic in terms of the distributed pressure and ice motions. The present work employs two realistic ice load models: a dynamic 4D pressure model, and a validated "crushable foam" ice model. Results using these realistic ice load models lend credence to previous findings and enable more realistic modeling of the whole ice-ship impact scenario.
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response of iacs uri ship structures to real time full scale operational ice loads
SNAME Transactions Volume 120, 2012Co-Authors: Bruce W T Quinton, Claude Daley, Robert E. GagnonAbstract:Moving ice loads can incite significantly different structural responses in a steel grillage structure than can stationary ice loads. This is significant because the accepted standard for the design and analysis of ice-classed ship structures is to assume a stationary ice load (LACS URI 12.3.1). The following work utilizes the 4D Pressure Method ((Quinton, Daley, and Gagnon 2012)) to apply thirty-five of the most significant ice loads recorded during the USCGC Polar Sea trials (1982-86), to fourteen IACS URI PCI-7 classed Grillages; using explicit finite element analyses. Two grillage variations for each of the seven PC classes were examined: Grillages with "built T" framing and Grillages with "flatbar" framing. In short, the following simulations directly employ real-time/real-space measured full-scale ice loads, and thus provide insight into the structural capabilities of the various IACS URI polar classes when subject to actual (moving) ice loads.
Robert E. Gagnon - One of the best experts on this subject based on the ideXlab platform.
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realistic moving ice loads and ship structural response
The Twenty-second International Offshore and Polar Engineering Conference, 2012Co-Authors: Bruce W T Quinton, Claude Daley, Robert E. GagnonAbstract:Prior work by the authors has shown that moving ice loads incite a significantly different structural response in steel grillage structures than do stationary ice loads. The work was based on a validated explicit numerical model of a steel grillage. The main drawback was that the ice load model was largely unrealistic in terms of the distributed pressure and ice motions. The present work employs two realistic ice load models: a dynamic 4D pressure model, and a validated "crushable foam" ice model. Results using these realistic ice load models lend credence to previous findings and enable more realistic modeling of the whole ice-ship impact scenario.
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response of iacs uri ship structures to real time full scale operational ice loads
SNAME Transactions Volume 120, 2012Co-Authors: Bruce W T Quinton, Claude Daley, Robert E. GagnonAbstract:Moving ice loads can incite significantly different structural responses in a steel grillage structure than can stationary ice loads. This is significant because the accepted standard for the design and analysis of ice-classed ship structures is to assume a stationary ice load (LACS URI 12.3.1). The following work utilizes the 4D Pressure Method ((Quinton, Daley, and Gagnon 2012)) to apply thirty-five of the most significant ice loads recorded during the USCGC Polar Sea trials (1982-86), to fourteen IACS URI PCI-7 classed Grillages; using explicit finite element analyses. Two grillage variations for each of the seven PC classes were examined: Grillages with "built T" framing and Grillages with "flatbar" framing. In short, the following simulations directly employ real-time/real-space measured full-scale ice loads, and thus provide insight into the structural capabilities of the various IACS URI polar classes when subject to actual (moving) ice loads.
Tayfun Dede - One of the best experts on this subject based on the ideXlab platform.
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jaya algorithm to solve single objective size optimization problem for steel grillage structures
Steel and Composite Structures, 2018Co-Authors: Tayfun DedeAbstract:The purpose of this paper is to present a new and efficient optimization algorithm called Jaya for optimum design of steel grillage structure. Constrained size optimization of this type of structure based on the LRFD-AISC is carried out with integer design variables by using cross-sectional area of W-shapes. The objective function of the problem is to find minimum weight of the grillage structure. The maximum stress ratio and the maximum displacement in the inner point of steel grillage structure are taken as the constraint for this optimization problem. To calculate the moment and shear force of the each member and calculate the joint displacement, the finite elements analysis is used. The developed computer program for the analysis and design of grillage structure and the optimization algorithm for Jaya are coded in MATLAB. The results obtained from this study are compared with the previous works for grillage structure. The results show that the Jaya algorithm presented in this study can be effectively used in the optimal design of grillage structures.
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Optimum design of grillage structures to LRFD-AISC with teaching-learning based optimization
Structural and Multidisciplinary Optimization, 2013Co-Authors: Tayfun DedeAbstract:In this paper, a new efficient optimization algorithm called Teaching–Learning-Based Optimization (TLBO) is used for the optimum design of grillage systems based on the LRFD-AISC (Load and Resistance Factor Design-American Institute of Steel Construction). Cross sectional area of W-shapes are considered as discrete design variables. Various grillage structures are designed to show the efficiency of the TLBO algorithm. The results obtained from this study are compared with those reported in the literature. It is concluded that the TLBO algorithm presented in this study can be effectively used in the optimal design of grillage structures.
R. Ajit Shenoi - One of the best experts on this subject based on the ideXlab platform.
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Implications of failure criteria choices on the rapid concept design of composite grillage structures using multiobjective optimisation
Structural and Multidisciplinary Optimization, 2013Co-Authors: A. J. Sobey, J I R Blake, R. Ajit ShenoiAbstract:Grillage topologies are commonly used in many composite structural applications to produce low mass designs that have a high stiffness. While composite failure criteria are being compared in many different simple structures, for example plates and tubes, literature must also compare more complicated applications, including Grillages, as there are distinct differences in behaviour. This paper therefore performs analysis of grillage structures with more up to date failure criteria, taken from the world wide failure exercise, than previously investigated. The grillage theory selected is that of Navier theory with elastic equivalent properties due to its low computational expense for use with a genetic algorithm to optimise a composite structure. The results take an example from leisure boatbuilding showing the Grillages produced from the different limit states, comparing the cost and mass. The final results show that the method allows a rapid analysis of Grillages and that the selection of the limit state has an important effect on the optimised grillage topology.
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monte carlo reliability analysis of tophat stiffened composite plate structures under out of plane loading
Reliability Engineering & System Safety, 2013Co-Authors: A. J. Sobey, J I R Blake, R. Ajit ShenoiAbstract:Abstract Composite materials are often utilised for their high strength to weight ratio, excellent corrosion resistance, etc. but are also characterised by variabilities and uncertainties in their mechanical properties owing to the material make-up, process and fabrication techniques. It is essential that modelling techniques continue to be developed to take account of these variabilities and uncertainties and as more complicated structures are developed it is important to have rapid assessment methods to determine the reliability of these structures. Grillage analysis methods have been previously used for assessment of tophat stiffened composite structures using simple failure criteria. As new criteria are introduced, such as by the World Wide Failure Exercise, the response of more complex topologies must be introduced. This paper therefore assesses the reliability of composite Grillages using Navier grillage method incorporating up to date failure criteria. An example, taken from boatbuilding, is used to show the results of using these more complex assessment methods showing that it is of high importance to use the correct assessment criteria.
