Optimal Design of Double-Layer Grids
Double-layer grids belong to the category of space structures and consist of two planar networks of members forming the top and bottom layers parallel to each other and interconnected by vertical and inclined web members. Double layer grids are characterized by ball joints with no moment or torsional resistance; therefore, all members can only resist tension or compression. In the last decades, a number of meta-heuristic algorithms have been developed and used for structural optimization problems. Double-layer grids have a great number of structural elements, and therefore optimization techniques can be rewardingly employed to achieve economic and efficient designs of them. Here, five different types of double-layer grids are studied and optimized utilizing the colliding bodies optimization (CBO), enhanced colliding bodies optimization (ECBO), vibrating particles system (VPS), and a hybrid algorithm called MDVC-UVPS. The cross-section areas of the grid elements are considered as discrete design variables and all of them are selected from a list of tube sections available in AISC-LRFD. Strength, stability, and displacement constraints are considered for each example.