Advanced Steel Construction

Vol. 2, No. 6, pp.400-415  (2006)



D. Safari1 and Mahmoud R. Maheri2,*

1PhD Candidate, Department of Civil Engineering, Shiraz University, Shiraz, Iran

2Professor of Civil Engineering, Faculty of Engineering, Shiraz University,

P O Box 71345/1676, Shiraz, Iran, Tel: +98-711-6287505, Fax: +98-711-6286619

*(Corresponding author:E-mail:This email address is being protected from spambots. You need JavaScript enabled to view it. and

Received:9 April 2005;Revised:7 May 2006;Accepted:9 May 2006





In steel structures, steel bracing is often used to resist the seismic or wind-induced lateral forces. Theoptimum positions of the braces are generally determined by trial and error or through previous experiences, usuallywith the objective that the distance between floor centres of mass and stiffness are reduced to a minimum and that aviable load path is provided throughout the lateral resisting system. This process is cumbersome and the trial anderror optimization is usually incomplete. In this paper, topology optimization of steel braces in 2D steel frames iscarried out using a simple Genetic Algorithm. To improve the GA optimization of the brace-frame system, theory ofgraphs is also utilized as a heuristic operator. The objective is minimization of the weight of the steel frame subjectto strength and drift constraints. Other independent constraints adopted include; architectural constraints and thenumber of braced panels. It is shown that the GA can be used effectively to optimize the topology of bracings in steel structures. Also, it is shown that utilizing the graph theory as a heuristic operator, greatly improves theconvergence rate of the optimization.


Keywords:Bracing, topology optimization, genetic algorithm, theory of graphs, seismic design, steel structures.


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