An experimental study on variability of deformation characteristics of concrete in compression

Introduction. An experimental study on variability of deformation characteristics of concrete and an assessment of its influence on the bearing capacity of eccentrically compressed reinforced concrete elements were performed. In pursuance of effective regulatory documents, a non-linear deformation model was applied to perform the strength analysis of standard cross sections of reinforced concrete structures. The application of this method in probabilistic design is also of interest. Analytical functions approximating the true σ–ε diagram, made for concrete, use strength and deformation characteristics of concrete as parameters. However, variability of deformation characteristics of concrete has not been sufficiently studied, although it may have significant influence on results of analyses. Materials and methods. Complete σ–ε diagrams were made for uniaxially compressed concrete to solve this problem. These diagrams were applied to numerically assess the influence of variability of deformation characteristics of concrete on the bearing capacity of an eccentrically compressed reinforced concrete element in terms of its standard cross section. A non-linear deformation model was used to identify the bearing capacity. Results. The experiment has proven substantial variation of diagram shapes within the same strength class. The influence of the εb0 value of ultimate deformations of concrete on the bearing capacity is demonstrated for a standard cross section as a result of the strength analysis of an eccentrically compressed reinforced concrete element. The strength analysis was performed by applying experimental σ–ε diagrams made for uniaxially compressed concrete. Conclusions. The analysis of the findings has shown that the value of ultimate deformations of concrete exposed to uniaxial compression affects the bearing capacity of eccentrically compressed reinforced concrete elements. The degree of influence depends on concrete strength, reinforcement percentage and the eccentricity of a longitudinal force.