Ultimate state of the support zone of reinforced concrete beams

A brief review of actual methods of calculation of the shear forces is performed; the calculated dependences are analyzed and their estimation is given. The shortcomings of the methods are noted, the main one is the empirical approach to the solution of the problem. The features of destruction of reinforced concrete elements along an inclined section are considered; the mechanism of destruction, on which the actual normative documents are based, is analyzed. A method of design of reinforced concrete elements under the action of shear forces is proposed. The method is developed on the basis of analysis of the stress-strain state of the support zone of a reinforced concrete beam of rectangular cross-section. In the design work, two stages are distinguished. This made it possible to avoid empirical coefficients in the equations. A numerical model was created. Stress distribution in the beam was obtained and analyzed. Conclusions about the actual stress distribution in the compressed zone of concrete above the top of the inclined crack and the actual compressive strength of concrete are made. The proposed design method made it possible to describe the process of destruction of the inclined section in strict accordance with the experimental data. The proposed approach allows to obtain accurate results not only for reinforced concrete elements of simple cross-section (rectangular, T-section), but also for other shapes of sections of a more complex configuration.