Minimum weight design of structures with application to elastic grillages

A review is given of some mathematical programming methods suitable for optimization of structures needing matrix methods for analysis. An application is presented for elastic flat grillages made of straight orthogonal beams normally loaded. Empirical relationships are used to relate beam section properties so that each beam element has only one design variable. Optimization results are obtained by methods of stress‐ratio, linear programming‐cutting plane and usable‐feasible gradient directions. A comparison of the efficiency of these methods is given for the grillage designs which are shown to have non‐convex stress constraints and numerous relative optima. Instances are given of non‐fully stressed global optima and fully stressed designs which are not local optima for cases with only stress constraints. Discussions include locating the global optima for grillage designs and extensions of the methods presented to other structural design problems.