beams, a limiting condition, static definability, bending moment, composites.

The beginning of the study of reinforced concrete structures was initiated by A. A. Gvozdev [4], who introduced widely known model of ideal rigid plastic material in design practices, and on its basis held a large number of calculations of the load capacity of various building structures [2], [5]. The model was quite simple and comfortable in design engineering practice and has been widely developed in our country [9], [6] and abroad [3], [7], [8]. However, we should note that although in the above-mentioned papers it is often pointed out that the calculations have been carried out for construction structures of reinforced concrete, the most important property of concrete and reinforced concrete structures, associated with their significant varying resilience in tension and compression [2], [10], [11] is not actually considered while carrying out specific calculations for this model. In this case, the calculations are limited to the simplest forms of the rod cross section and the simplest loading and fastening conditions. Modern technological capabilities to create a flexible set of hybrid laminated reinforced structures in which the cross section of the layers can be implemented in various grade concrete, reinforcing elements and reinforcement structures, are not taken into account.

In this paper, on the basis of the ideas of the model of ideal plastic and hardening rigid-plastic materials we will consider an approach of constructing a generalized model of plastic deformation and limit state corresponding to the initial destruction of arbitrary reinforced rods based on concrete.

Nemirovsky Yuri Vladimirovich

e-mail: nemirov@itam.nsc.ru, Dr. Sci. Phys. & Math., Professor, Institute of Theoretical and Applied Mechanics S. A. Christianovich Siberian Branch of the Russian Academy of Sciences, Novosibirsk, Russia.

Tikhonov Sergey Vladimirovich

e-mail: strangcheb@mail.ru, Candidate of Phys. & Math., Assoc. Professor, Department Matematical Analysis, Algebra and Geometry, I. Yakovlev Chuvash State Pedagogical University, Cheboksary,  Russia.