METHOD OF CALCULATION OF STRENGTH IN INCLINED SECTIONS OF BEAM REINFORCED CONCRETE ELEMENTS

Abstract

The boundary of application of methods of truss analogy and disk model for calculation of strength on inclined sections of the flexural reinforced concrete members is established. The problem of the strength of an inclined prism loaded at the ends by compressed normal and tangential forces is considered. Plastic strain is considered to be localized in thin layers on the failure surface, which is characteristic of the ultimate state of concrete under the shear. The analysis of the results obtained by the variational method in the theory of plasticity allows to make reasonable changes to determine the strength of the compressed inclined element. Areas of realization of failure of reinforced concrete structures by conventional compressed member and compressed zone over dangerous inclined crack on action of shear force on the basis of application of criterion of the minimum ultimate force perceived by elements are defined. The influence of concrete class, relative shear span and intensity of shear reinforcement on the strength of elements is specified. The offered technique of calculation of strength of reinforced concrete structures on inclined sections on action of shear force allows to receive more effective structural designs. Determination of the values of the coefficient of shear reinforcement of sections of structures near the supports, which corresponds to the boundary of the considered cases of failure by shear within the inclined strip and the compressed zone of concrete over the dangerous inclined crack. The prospects of application of the theory of plasticity for improvement of structural designs of flexural reinforced concrete members are established. The application of the theory of plasticity allows to specify the bearing capacity, which is determined by the strength of the inclined strip, as part of the truss analogy, and the strength of the dangerous inclined crack.