Transformation of concrete deforming diagrams in conditions of uniform and non-uniform stress states

Abstract

The aim of the research is formulated, which is the theoretical substantiation, development and testing of the concrete state diagram, suitable for use to calculations of the strength of bended reinforced concrete elements based on the deformational model, as well as for more complete assessment of non-uniform stress-strain state of the cross-sections of elements at all stages of their loading up to the destruction directly on the values of the relative strains of concrete and the corresponding stresses.
 In this paper, an analytical method of converting the parameters of reference concrete deforming diagrams, which are determined experimentally during standard tests of concrete prismatic specimens by short-term axial compression and tension up to the destruction in «soft» mode of loading, into parameters of simulated transformed diagrams, which correspond to the «rigid» mode of loading of concrete, is developed. The way of simultaneous application of analytical expressions for the specified defoming diagrams, which describe the operation of concrete in conditions of uniform compression, for transition to the state diagram, which displays the functional relationship between the stresses and strains of the concrete compressed zone in bended concrete and reinforced concrete elements, cross-sections of which operate in conditions of non-uniform stress state, is proposed.
 The results of testing the obtained mathematical model of the concrete state diagram during the calculation by different methodics of strength of the normal cross-sections of bendable reinforced concrete elements are presented.
 It has been determined that a promising direction for further experimental and theoretical research is the study of the application of the developed methodics of graphical building and mathematical descripting of concrete deforming diagrams under conditions of uniform and non-uniform compression to the calculation of concrete and reinforced concrete elements that are operated under the action of long-term and short-term low-cycle loadings.