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Structural Engineering and Mechanics
  Volume 70, Number 3, May10 2019, pages 367-380
DOI: http://dx.doi.org/10.12989/sem.2019.70.3.367
 


Multi-objective topology and geometry optimization of statically determinate beams
Agata Kozikowska

 
Abstract
    The paper concerns topology and geometry optimization of statically determinate beams with arbitrary number of supports. The optimization problem is treated as a bi-criteria one, with the objectives of minimizing the absolute maximum bending moment and the maximum deflection for a uniform gravity load. The problem is formulated and solved using the Pareto optimality concept and the lexicographic ordering of the objectives. The non-dominated sorting genetic algorithm NSGA-II and the local search method are used for the optimization in the Pareto sense, whereas the genetic algorithm and the exhaustive search method for the lexicographic optimization. Trade-offs between objectives are examined and sets of Pareto-optimal solutions are provided for different topologies. Lexicographically optimal beams are found assuming that the maximum moment is a more important criterion. Exact formulas for locations and values of the maximum deflection are given for all lexicographically optimal beams of any topology and any number of supports. Topologies with lexicographically optimal geometries are classified into equivalence classes, and specific features of these classes are discussed. A qualitative principle of the division of topologies equivalent in terms of the maximum moment into topologies better and worse in terms of the maximum deflection is found.
 
Key Words
    Pareto optimality; lexicographic ordering; beams; topology and geometry optimization; bending moment; deflection
 
Address
Faculty of Architecture, Bialystok University of Technology, Oskara Sosnowskiego 11, 15-351 Bialystok, Poland
 

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