MAIN PARAMETERS OF THE DEFORMATION DIAGRAM OF COMPRESSED CONCRETE UNDER THE DYNAMIC LOADS

The article is devoted to the features of modeling the deformation diagram of compressed concrete under the dynamic loads action. The specified modeling involves the transformation of the standard deformation diagram of compressed concrete, obtained during static load tests, into a calculated one. It is aimed at the further development of the generalized deformation-force model of concrete and reinforced concrete resistance to force effects. The improved concrete deformation model is based on the law of conservation of the specific potential energy of concrete ultimate deformation (destruction), regardless of its strain rate. A critical analysis of the currently known research results carried out by other authors on the specified topic was carried out. The main attention is paid to the determining parameters of compressed concrete deformation diagram under the dynamic loads action: the known dynamic increase factor (DIF), the level of concrete ultimate deformability and the degree of elasticity modulus variability. The main advantages and disadvantages of the currently existing methods of determining these parameters are analyzed.The main tasks of these studies are formulated. An analytically justified function of the maximum possible DIF values was obtained. It is shown that DIF directly depends on the well-known integral characteristic of concrete - the elastic-plasticity coefficient. The functional dependence of DIF on the compressed concrete strain rate under the different intensity dynamic loads action is proposed. An analytical relationship between the concrete elastic-plasticity coefficients under the action of dynamic and static loads has been established. A simple functional dependence of the compressed concrete deformability level on its class and the concrete strain rate was obtained. The expediency of using the initial modulus of concrete deformations (elasticity) in reinforced concrete elements and structures calculation methods is indicated.