This paper discusses the effect of prestress on the minimum weight design of singly loaded trusses of fixed geometry which are required to satisfy stress constraints. Both general trusses and trusses falling in the special category of structures whose design requires a predetermined ratio for the areas of cross-section (same for simplicity) are considered. Formally ynthesized as nonlinear programming problems they are later reduced to linear proyramming problems by removing the constitutive equations from the formulation by utilizing the results of theorems relating to realizability through prestressing.

With equilibrium only left to be considered the general truss problem reduces identically to that of optimal design without prestress having the well known properties of fully stressedness and statical determinacy. Prestressing, therefore, has no meaning as far as weight is concerned. However, for trusses within the aforementioned special category, prestressing can reduce the weight since the structure is understressed due to the fact that usually one member governs the design. Posterior considerations are given for attaining the prestress and an example that surfaces weight advantages are presented.

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