Abstract
It is proposed a complex resistance computational model of reinforced concrete constructions in buildings and structures under the action torsion with bending. It consists of from the block near the support (formed by a spatial crack and a compressed concrete zone closed by it – a spatial section k) and a second block, which is formed by a vertical cross section I–I passing perpendicularly to the longitudinal axis of the reinforced concrete element along the edge of the compressed zone, which closes the spatial spiral-shaped crack. In this case, as the calculated forces are taken into account in the spatial section: normal and tangential forces in the concrete of the compressed zone; components of axial and “dowel” efforts in the working reinforcement, intersected by a spiral spatial crack. The formation of a spatial crack occurs perpendicular to the direction of the main deformations of the elongation of concrete at the lower edge of the reinforced concrete element. The location of the compressed fiber is close to the direction of the main deformation of the concrete. It forms a compressed zone together with the vertical cross-section and having the form of a rectangle with a height xb,k, formed by a spatial crack. The vertical cross-section is refracted and passes along the lateral planes of the compressed zone, coinciding with the axes of the angular longitudinal reinforcement. Destruction of the concrete compressed zone occurs in a certain volume adjacent to the middle section by the size l2 of its broken section when the intensity of deformations εi reaches its limiting values on octahedral sites. Thus, the spatial crack has a spiral shape closing on a broken vertical section of the compressed zone. The resolving equations are constructed that form a closed system and the Lagrange function is unified. Using the partial derivatives of the constructed function with respect to all the variables entering into it and equating them to zero, an additional system of equations is constructed. The dependence is obtained after the corresponding algebraic transformations, that allows us to search for the projection of a dangerous spatial crack cinc.
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