Almost every real world problem involves simultaneous optimization of several incommensurable and often competing objectives which constitutes a multi-objectiveoptimization problem. In multi-objectiveoptimization pr...
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Almost every real world problem involves simultaneous optimization of several incommensurable and often competing objectives which constitutes a multi-objectiveoptimization problem. In multi-objectiveoptimization problems the optimal solution is not unique as in single-objectiveoptimization problems. This paper is concerned with large-scale structuraloptimization of skeletal structures such as space frames and trusses, under static and/or seismic loading conditions with multiple objectives. Combinatorial optimization methods and in particular algorithms based on evolution strategies are implemented for the solution of this type of problems. In treating seismic loading conditions a number of accelerograms are produced from the elastic design response spectrum of the region. These accelerograms constitute the multiple loading conditions under which the structures are optimally designed. This approach for treating seismic loading is compared with an approximate design approach, based on simplifications adopted by the seismic codes, in the framework of multi-objectiveoptimization.
Ship structural design often deals with multiple objectives such as weight, safety, and cost. These objectives usually conflict with each other, and optimizing a particular solution with respect to a single objective ...
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ISBN:
(纸本)9780791845493
Ship structural design often deals with multiple objectives such as weight, safety, and cost. These objectives usually conflict with each other, and optimizing a particular solution with respect to a single objective can result in unacceptable results with respect to the other objectives. A reasonable solution to a multi-objective problem is to investigate a set of solutions, each of which satisfies the objectives at an acceptable level without being dominated by any other solution. Genetic algorithms have been demonstrated to be particularly effective to determine excellent solutions to these problems. In this paper a multi-objective GA, called Vector Evaluated Genetic Algorithm (VEGA) is formulated and used to optimize a large and complex thin-wall structure (a complete cargo hold of a 200,000 ton oil tanker) on the basis of weight, safety and cost. The structure weight and cost and all of the stresses are calculated using a realistic finite element model. The structure adequacy is then evaluated using the ALPS/ULSAP computer program (Paik and Thayamballi, 2003) which can efficiently evaluate all six ultimate limit states for stiffened panels and grillages. This example was chosen because the initial design is severely inadequate. The results show that the proposed method can perform ultimate strength based structuraloptimization with multi-objectives, namely minimization of the structural weight and cost and maximization of structural safety, and also that the method is very robust.
multi-objective structural optimization problems (MOSOPs) with two objectives are widely discussed in the literature. Most MOSOPs that refer to trusses are formulated to minimize the weight and the maximum nodal displ...
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multi-objective structural optimization problems (MOSOPs) with two objectives are widely discussed in the literature. Most MOSOPs that refer to trusses are formulated to minimize the weight and the maximum nodal displacement. This paper formulates MOSOPs with several objective functions combined with various formulations. The objective functions are the weight, the natural frequencies of vibration, the maximum nodal displacement, and the critical load factor concerning the structure's global stability. The design variables are the cross-sectional areas of the bars, the nodal coordinates, and the presence or absence of bars in the final optimized structure. The third evolution step of generalized differential evolution (GDE3), the success history-based adaptive multi-objective differential evolution (SHAMODE) and the success history-based adaptive multi-objective differential evolution with whale optimization (SHAMODE-WO), and the multi-objective meta-heuristic with iterative parameter distribution estimation (MM-IPDE) are the differential evolution algorithms used in this paper. The experiments refer to the 10-, 25-, 56-, 72-, 120-, and 582-bar trusses and a 33-bar ground-structure system. multi-criteria decision-making (MCDM) is adopted to extract solutions from the Pareto front according to preferences of the decision-maker (DM) used in the ground-structure system. The complete data for each extracted solution are provided, including its optimized topology. (C) 2021 Elsevier Ltd. All rights reserved.
Flat plate floor systems are most often constructed in residential or mixed-use buildings for a variety of reasons such as shortening the construction time, reducing the floor height and achieving spatial flexibility....
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Flat plate floor systems are most often constructed in residential or mixed-use buildings for a variety of reasons such as shortening the construction time, reducing the floor height and achieving spatial flexibility. Additionally, flat plate floor systems have the largest volume among the structural members, so these systems have the largest influence on determining the carbon dioxide (CO2) emissions and costs incurred in the building construction and design stages. To analyze how CO2 emissions and amount of building materials in the floor system are affected by design parameters that can be considered in design and construction stages, a sustainable design model that minimizes CO2 emissions and construction costs of the flat plate floor system is developed. The developed technique was applied to design of flat plate floors with 126 different dimensions to analyze the effect of the design parameters on costs and CO2 emissions. Additionally, the performance of the proposed method was evaluated by applying it to design of a 47-story mixed-use building. The results indicates that active design parameters that determined the environmental impact and cost of flat plates were the yield strength of rebar, rebar diameter, slab thickness, and the compressive strength of concrete.
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