Optimization of Shallow Trusses Against Limit Point Instability

The problem of the maximization of the critical load (limit point instability) of shallow space trusses of constant volume or weight is considered. Exact solutions being possible in simple cases, a detailed investigation of the question of the uniqueness of the optimum designs for two- and four-bar shallow truss problems is carried out. The optimized trusses satisfy the constant-strain energy density criteria and the load maximization problem is verified to be the dual of the minimization of the total potential energy.