A reformulation of the ant colony optimization algorithm for large scale structural optimization

This study intends to improve performance of ant colony optimization (ACO) method for structural optimization problems particularly with many design variables or when design variables are chosen from large discrete sets. The algorithm developed with ACO method employs the so-called pheromone scaling approach to overcome entrapment of the search in a poor local optimum and thus to recover efficiency of the method for large-scale optimization problems. Besides, a new formulation is proposed for the local update parameter in the algorithm. The efficacy of the proposed algorithm is quantified using two numerical design examples chosen from practical size optimum design of steel structures. The results obtained with the proposed algorithm are compared with those of other methods, such as particle swarm optimization (PSO), harmony search optimization (HSO) and genetic algorithms (GAs). The design problems are formulated according to the provisions of ASD-AISC (Allowable Stress Design Code of American Institute of Steel Institution)