Optimum design of structures with limited ductility

A minimum volume design problem formulation for elastic perfectly plastic structures, subjected to loads quasi-statically variable within a given domain, is proposed. In particular, the actions are defined as the combination of fixed loads and perfect cyclic loads. The optimal design problem is formulated according to a plastic shakedown criterion so that the incremental collapse and the instantaneous collapse are certainly prevented when the structure is subjected to the prescribed amplified loads. In addition, further appropriate constraints on the plastic deformations characterizing the structure response are imposed. In particular, suitable limits on the plastic deformations occurring at the limit state of the plastic shakedown are imposed and some chosen measures of the plastic deformations related to the transient phase structural response are suitably bounded. For computational purposes an appropriate solution procedure is utilized. The present optimum design formulation shows very promising features in order to be numerically applied.