Optimum Design of Steel Continuous Girders Using Suboptimization of Girder Elements

Structural Optimization

1998

In practical structural design problems, the designer should take into account several objectives, such as economics, safety, serviceability, aesthetic feeling and so on, and relative evaluations among these different characteristic objectives have some tolerances or fuzziness. For these reasons, the practical optimum structural design process concerning multiobjectives can be defined as a kind of compromising optimum decision-making process with fuzziness. In this paper, a rational, .systematic and efficient fuzzy optimum design method for structural systems is developed by combining a suboptimizatio~ concept and fuzzy decisionmaking techniques at the discrete combinations of common design variables. The design method is applied to an optimum design problem of a large scale prestressed concrete bridge system considering two objectives; the total construction cost and aesthetic feeling. The rationality, the systematic design process and the efficiency of the proposed method are demonstrated.

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Section: Introductionmentioning

confidence: 99%

An approach to multicriteria fuzzy optimization of a prestressed concrete bridge system considering cost and aesthetic feeling

Structural Optimization

1998

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“…However, very little attention has yet been paid to optimization problems with material selection, which require a discretelcontinuous formulation. 2,3,9,12,13. 16 We have presented a hybrid optimal synthesis method for truss structures in which the coordinates of the panel points, cross-sectional areas, and discrete material kinds of member elements are optimized simultaneously subject to stress and displacement constraints.…”

Section: Introductionmentioning

confidence: 99%

Total Optimal Synthesis Method for Truss Structures Subject to Static and Frequency Constraints

Computer aided Civil Eng

1995

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In a previous study, we presented an efficient optimal structural synthesis method for truss structures in which the design variables are coordinates of the panel points, cross‐sectional areas, and discrete material kinds subjected to stress and displacement constraints. In this paper, the synthesis method is extended to solve design problems subject to stress, displacement, and fundamental natural‐frequency constraints. The design problem is formulated in terms of discrete material kinds and continuous shape and sizing variables and which are approximated by a convex and separable subproblem. The approximate subproblem is expressed in direct and/or reciprocal design variables and shape, material, and sizing sensitivities. Each subproblem is solved by a two‐stage minimization process. In the first stage, the continuous shape and sizing variables are optimized by a dual method. Second, the discrete material and continuous sizing variables are improved by a discrete sensitivity analysis. Using the proposed two‐stage minimization procedure, both the discrete material kinds and the continuous shape and sizing variables can be systematically improved to obtain an optimal solution. The rigorousness, reliability, and efficiency of the method are illustrated by applying it to the minimum cost design of truss structures subject to stress, displacement, and fundamental natural‐frequency constraints.

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Optimal synthesis method for transmission tower truss structures subjected to static and seismic loads

Structural and Multidisciplinary Optimization

2004