Optimal design of elasto-plastic structures subjected to normal and extreme loads

When in the design of structures extreme loadings such as short time, high intensity dynamic pressure (explosion), impact or earthquake have to be taken into consideration then, except for special cases, the plastic reserves of the material can be utilized, but the development of excessive plastic deformations, residual displacements and the collapse have to be prevented. Following this design concept in this paper three appropriate methods are presented for the determination of the optimal layout of material of elasto-plastic structures (beams, frames, trusses and plates) subjected to extreme loading. The investigation is extended also to the case when in the optimal design in addition to one of the extreme loads the normal (working) loads can be separately or simultaneously taken into consideration.