Automated Design of Frame Structures

Methods of automated design and optimization of statically indeterminate frames by means of nonlinear programming are reviewed, with particular emphasis on the sequential unconstrained minimization technique (SUMT) employed by the writers. In this approach the proper choice of initial response factor is of particular importance in cases with several local optima. An extended penalty function technique allows infeasible initial designs. When a computer with 60 bits word length is used, gradient directions may be obtained with sufficient accuracy employing a single step finite difference scheme. Efficient interpolation and reanalysis techniques are incorporated in order to reduce required computer time. Considerable reduction in numerical effort is also obtained employing a scheme of suboptimization. The developed algorithm performs well for several complex test examples including problems for which the feasible region is nonconvex, and local optima are present.