OPTIMIZATION OF SKELETAL STRUCTURES USING A HYBRIDIZED ANT COLONY-HARMONY SEARCH- GENETIC ALGORITHM

Abstract

Ant Colony Optimization (ACO) has been used as one of the popular meta-heuristicalgorithms in structural optimization. In this algorithm, the selected cross sections are chosenaccording to a parameter called “probability ratio". This parameter and the way to choose the crosssections from a list of cross sections, are the most important points in the optimization process.Though the Ant Colony algorithm has a special ability in achieving the optimal point, in somecases in order to avoid local optima, the utilization of special techniques is needed. In the presentpaper, the first aim is to use Harmony Search (HS) algorithm to increase the local search ability ofthe ACO. In this way a combined algorithm, denoted by HACOHS, is obtained with specialabilities to achieve a global optimum. For this purpose, optimal design of skeletal structures suchas trusses and steel frames is considered using the HACOHS. However, in the process ofoptimization by HACOHS method, several GA selections are employed at the cross sectionselection stage. Utilizing the Tournament (HACOHS-T), Roulette wheel (HACOHS-Ro), andRank (HACOHS-Ra) methods it is found that the HACOHS-T is the most efficient of thesealgorithms for optimal design of skeletal structures.