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The paper deals with the optimization of a single-storey timber building structure designed from timber portal frames connected with steel purlins, rails and façade columns. While the portal frames are made of the glued laminated timber with rectangular cross-sections, purlins, rails and façade columns are made of commercially available steel I-profiles. The portal frames are supported by square concrete pad foundations. The building structure is optimized by a mixed-integer non-linear programming (MINLP). The optimization model is developed. The objective function defines the material costs of the structure. The objective function is subjected to structural analysis and design constraints defined according to Eurocode standards. The Modified Outer-Approximation/Equality-Relaxation algorithm (OA/ER) and the linked multi-level strategy are applied. The optimization determines the minimum material costs of the structure, the optimal number of glulam frames and steel members and all standard/discrete cross- sections. A numerical example at the end of the paper shows the efficiency of the proposed optimization approach.
cost optimization, mixed-integer non-linear programming (MINLP), steel structures, structural optimization, timber building, timber structures
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