Techno Press
Techno Press

Steel and Composite Structures   Volume 15, Number 5, November 2013, pages 519-538
DOI: http://dx.doi.org/10.12989/scs.2013.15.5.519
 
An efficient genetic algorithm for the design optimization of cold-formed steel portal frame buildings
D.T. Phan, J.B.P. Lim, T.T. Tanyimboh and W. Sha

 
Abstract     [Full Text]
    The design optimization of a cold-formed steel portal frame building is considered in this paper. The proposed genetic algorithm (GA) optimizer considers both topology (i.e., frame spacing and pitch) and cross-sectional sizes of the main structural members as the decision variables. Previous GAs in the literature were characterized by poor convergence, including slow progress, that usually results in excessive computation times and/or frequent failure to achieve an optimal or near-optimal solution. This is the main issue addressed in this paper. In an effort to improve the performance of the conventional GA, a niching strategy is presented that is shown to be an effective means of enhancing the dissimilarity of the solutions in each generation of the GA. Thus, population diversity is maintained and premature convergence is reduced significantly. Through benchmark examples, it is shown that the efficient GA proposed generates optimal solutions more consistently. A parametric study was carried out, and the results included. They show significant variation in the optimal topology in terms of pitch and frame spacing for a range of typical column heights. They also show that the optimized design achieved large savings based on the cost of the main structural elements; the inclusion of knee braces at the eaves yield further savings in cost, that are significant.
 
Key Words
    optimization; cold-formed steel; portal frames; niching; real-coded genetic algorithm
 
Address
(1) D.T. Phan: Department of Civil Engineering, Universiti Tunku Abdul Rahman, Kuala Lumpur, 53300, Malaysia;
(2) J.B.P. Lim and W. Sha: School of Planning, Architecture and Civil Engineering, Queen\'s University Belfast, David Keir Building, Belfast, BT9 5AG, UK;
(3) T.T. Tanyimboh: Department of Civil and Environmental Engineering, University of Strathclyde, John Anderson Building, Glasgow, G4 0NG, UK.
 

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