Multicriterion design of frames with constraints on buckling

Abstract

The present paper is devoted to the optimal design of frame structures subjected to static and dynamic loading assuming the material behaviour as elastic perfectly plastic. The relevant optimal design problem is formulated as a minimum volume search problem. The minimum volume structure is determined under suitable constraints on the design variables as well as accounting for different resistance limits: the elastic shakedown limit and the instantaneous collapse limit, considering for each limit condition suitably chosen amplified load combinations. The effects of the dynamic actions are studied on the grounds of the dynamic features of the structure taking into account the structural periods referring to the actual Italian Codes related to the structural analysis and design. The minimum volume design is developed at first as the search for the optimal structure with simultaneous constraints on the elastic shakedown behaviour and on the instantaneous collapse. Moreover, in order to avoid undesired further collapse modes, the structure will be constrained to prevent element buckling. The numerical applications are related to steel frames.