Combined structure, sparse grating, corrugated web, geometric parameters, optimal design, design variable.

Abstract

In the development of studies of a combined low-element truss with an incomplete (sparse) grating, a research was made looking for optimal geometric parameters (without changing the topology) and the distribution of forces and material, that reflect the current state of lightweight metal structure design, specific conditions of use and the requirements of existing regulations.The structural form, which is designated as a system with incomplete grating scheme, is investigated. It is extremely sensitive to changes in geometric parameters of the scheme. Studies have shown that the regulation of stress-deformed state (SDS) in the design process allows you to develop structures as rationally as possible. The optimal design method is used to find geometrical parameters that allow the necessary (upon some criteria) force distribution in truss elements by fixed loads. The algorithm is implemented in the form of a direct search method of Nelder-Mead with penalty functions, that is developed as modification of usual simplex Spendley-Hext-Himsworth method.Numerical study of combined system containing a rigidity beam with a corrugated web is carried out. Constructive constraints are recorded as inequalities/equations of strength and stability conditions according to design standards for steel structures DBN B.2.6-98. Optimal values of geometric parameters were obtained according to the criteria of minimum mass and reduced expenditures for low-element truss structure with spans of 24 - 36 m. It is shown that combined solutions in the range of (10… 20)% losses by both criteria are competitive for similar purpose buildings.