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

The theory of a limiting plastic condition based on model of a limiting is rigid-plastic material has appeared very convenient practical tool for an estimation of bearing ability of designs of various type and has received wide practical application [1-4]. At its use out of an attention field there are two important questions, the designs connected with operation in the conditions of enough developed plastic deformations: an estimation of maximum permissible factor of reliability of operation of designs from the materials possessing hardening; an estimation of degree of their residual damageability at excess by operational loadings of values of amplitudes of the found classical maximum loads. These questions become especially important for the composit designs created from materials with various character and degree of hardening behind a limit of elasticity. In the given work on an example of the elementary elements - bent composit beams, the approach is developed, allowing to receive answers to the questions formulated above.