Deformation of concrete of a reinforced concrete frame in the ultimate state

A model of static-dynamic deformation of compressed concrete in the ultimate state is proposed, as applied to the calculation scheme of a second-level reinforced concrete frame under a special impact. The main working hypotheses for determining the static-dynamic deformation of concrete are constructed and analytical dependencies are obtained for determining the ultimate deformations in concrete of the compressed zone during the transition of the n-times statically indeterminate system to the (n- 1) system. Concrete of the compressed zone is modeled by a representative volume in the form of a concrete prism of characteristic dimensions. For a reinforced concrete frame, a first-level calculation model with spatial sections simulating a complex stress state in a spatial crack of a complex-stressed beam is constructed. In the frame elements with the considered spatial sections, the distances between cracks and the ultimate deformations of concrete preceding destruction are taken into account.