Preliminary Design of Concrete Structures Using Genetic Algorithms and Spreadsheets

This paper presents the application of the genetic algorithm to the design of some common concrete structures in Hong Kong, namely, tall reinforced concrete building frameworks, long-span concrete portal frames and prestressed concrete beams or bridges using spreadsheet. Cross-sectional dimensions of member groups are treated as discrete design variables and the method aims to minimize the weight of the structure subject to various constraints like multiple inter-storey deflection constraints for tall building frameworks, various stress limitations under serviceability limit state for fully prestressed concrete beams or bending and shear strength under ultimate limit states for portal frames. These constraints are treated as penalty function during the evolutionary process. In addition to the usual selection, cross-over (2-point) and mutation operators of a genetic algorithm, various special operators are introduced and their effectiveness in accelerating the convergence of the algorithm and the minimal weight of the structure are investigated. To verify the effectiveness of the method, present results are compared with those obtained using optimality criteria method for tall building frame solutions. The results presented herein are only preliminary; further development of the method is currently in progress.