Review article

A promising way of strengthening reinforced concrete beams is using for these purposes a “shirt” made of steel fiber reinforced concrete. Firstly, in terms of the labor consumption, constructing of such “shirt” is comparable to the application of ordinary plaster, and, secondly, the observed increase in the bearing capacity of reinforced beams is quite comparable with the use of a steel clip. An analysis of the literature has shown that at the time of the publication preparation, that there exists no method for calculating such way of strengthening under consideration, there are no methods that would take into account the features of steel fiber concrete as a material, as well as the features of the joint operation of the “shirt” with the reinforced beam. In order to develop such a technique, the most appropriate thing, in our opinion, is using of the numerical diagram method, which is based on a discrete nonlinear deformation model. The authors have elaborated a detailed algorithm for calculating the strength, crack resistance and stiffness of reinforced concrete beams reinforced with steel fiber concrete using the considered method of strengthening beams along a normal section. The calculation results have been compared with our own experimental data and those of other authors. There has been found that the difference in the moment of destruction was 0.7 ... 16.5%, for the moment of cracking - 0.4 ... 19.6%, for the values of deflections - up to 19%, which indicates the efficiency of the proposed method and the possibility of its application for practical calculations.