Chekanovych O. Stress-strain state of reinforced concrete bending elements strengthened with a lever-rod system

The thesis is devoted to the design of the structure of a new lever-rod strengthening system for reinforced concrete bending elements and to the research into the stress-strain state of beams strengthened with this system. The system allows efficient redistribution of stresses between the compressed and tensile zones of the bending element, and compensates for the negative effect of external load. The unloading of the compressed zone and compression of the strained zone occur inversely proportionally to the values of the lever arm, which interacts with the tension bars and tie bars. The author presents an improved set of analytical methods, and a new computer program for determining the stress-strain state, carrying capacity, and deformability of such elements. The study carries out full-factor numerical analysis of 150 reinforced beams with different combinations of strengthening parameters, and determines their efficient ratio. To check the validity of the methods of analysis, samples of strengthened and control beams have been tested. The structure developed has been put into production for strengthening existing ribbed covering slabs.