Genetic algorithm based optimum bracing design of non-swaying tall plane frames

This paper presents a genetic algorithm based optimum design method for mul ti-storey non-swaying steel frames with different types of bracing. The des ign method obtains a frame and bracing system with the least weight by sele cting appropriate sections for beams, columns and bracing members from the standard set of steel sections. The algorithm accounts for serviceability a nd strength constraints as specified in BS 5950 (1990). The serviceability limit state included in the design problem is achieved by limiting the over all and intermediate storey drift in the building to height/300 as specifie d by the code. The strength constraints are in the form of inequalities as given in BS 5950 which ensures that the design capacity of the member is gr eater than the ultimate force it is subjected to. The design algorithm take s into account lateral torsional buckling of frame members, if they are bea m-columns. Bracing members are considered to be made out of back-to-back do uble equal-leg angle attached to gusset plates. The algorithm presented is used to design a number of tall frames with different bracing systems such as X, V and Z bracing. It is noticed that X-bracing produces the lightest f rame among the others. (C) 2001 Elsevier Science Ltd. All rights reserved.