Methods for Determining the Strength of Eccentrically Compressed Reinforced Concrete Rectangular Sections

Abstract

According to the results of the research of the author of the article, the shortcomings of the theory of calculating eccentrically compressed reinforced concrete elements laid down in the current regulatory documents with their justification on a specific example of calculation are presented. In the current regulatory documents to verify the bearing capacity of eccentrically compressed reinforced concrete elements, they proceed from the condition N ≤ N_sech. To determine N_sech, the height of the compressed zone of concrete x is determined depending on the value of the external load N. When testing the condition N ≤ N_sech, one can only conclude whether the column will withstand the specified load or not. However, it is not known what is the maximum load the N_max will withstand the column, since with a different value of N, in the calculations of the same column, we obtain a different value of x, and accordingly a different value of Nsech. The bearing capacity of the column is the ultimate load Nmax, which the column can withstand for an unlimited time without destruction. The ways of improving this calculation theory are suggested, which more fully reflect the actual intensely deformed limiting state of elements depending on the values of the longitudinal force eccentricity N.The following theory of calculations of eccentrically compressed reinforced concrete elements in the limiting state of the bearing capacity of normal sections, developed by the author, takes into account all possible stresses in the longitudinal reinforcement from R_S to R_SC, caused by different values of eccentricity e of longitudinal force. The theory is based on the joint solution of the equilibrium equations of longitudinal forces and internal forces with the equilibrium equations of bending moments in the limit state according to the strength of normal sections.The studies cited in the article open up the possibility of more economical design of eccentrically compressed reinforced concrete elements, as well as increase the reliability and durability in their operation.