Discrete Multicriterion Optimization of a Space Truss

Abstract

Final forming of a space truss used as roof in a sports or market hall is a result of searching for a solution which is the best one according to various criteria such as safety, reliability, economy, functionality and so forth. An illustration of this problem a numerical example of various optimizations of an orthogonal, double layer space truss of dimensions 24 × 24 m made of steel is shown in the paper. First, eight single-criterion objective functions such as: weight of members, weight of nodes, weight of columns, weight of whole truss, weight of walls and roofing elements made of steel, vertical displacements of a node in the middle of the truss, energy of deformation and a certain function of geometry of the truss were investigated assuming the number of divisions and the depth of the truss as decisive variables. The problems were formulated as discrete ones since the element cross-sections were selected from a finite catalogue. The All Variants Inspections Method was employed. For three among the aforementioned objective functions, describing weight of structure, displacement of the central node and the geometry of the truss, a discrete multicriterion optimization problem was formulated and solved. From the set of compromises a preferred sollution has been chosen by using the discrete functions and, the global criterion method.