Investigations of the stress-strain state of a compressed steel concrete column using digital image correlation method

The results of the investigation of deformation during axial compression of a steel-concrete round column with dimensions of 1000×102 mm on the testing machine Universal Testing Machine 4500 using a digital optical system Vic-3D are presented. The patterns of the evolution of strain field distributions on the surface of the steel shell of the column are obtained. A deformation diagram indicating the transition stages of elastic strains to inelastic ones is constructed. A jump-like dependence of the Poisson's ratio on the longitudinal relative strain of the steel concrete column during deformation of the steel concrete column is established. This phenomenon is explained under the assumption that the deformation process involves redistribution of the forces (deformations) among the components of the composite system at the stage of joint operation before separation of the steel/concrete media and operation of concrete beyond elastic strain under conditions of volumetric compression.