Optimum design of square free-standing communication towers

Free-standing communication towers with a square cross-section, subjected to multiple combinations of wind and dead loads, are optimally designed for least weight. The member areas and joint coordinates are treated as design variables of the tower to which a reasonable initial geometry is specified. Members are designed to satisfy stress, displacement and buckling limits, in addition to linking constraints between area variables in each panel of the tower. The fully stressed design is assumed to be optimal. Coordinate variables are linked to reduce the number of independent design variables. The design problem is, in effect, divided into two separate, but dependent, design spaces: one for member sizes and the other for joint coordinates. On changing coordinate variables, using the Hooke and Jevees pattern search algorithm, the member areas are treated as dependent design variables. It is found that the decomposition of the optimization problem into a multilevel problem simplifies the procedure for Ending the optimum design of free-standing towers. (C) 2002 Elsevier Science Ltd. All rights reserved.