The paper presents a brief historical reference of the theory of reinforced concrete structures calculation and its. It shows that modeling of concrete deformations makes it possible not only to carry out calculations of durability and to determine reinforced concrete elements deflection under the estimated load, but also to analyze their a stress-strain state at each stage. The study suggests a new model of concrete deformation which makes it possible to make calculations of concrete elements with characteristics which are different from those given in specification documents. The researchers use the proposed model of deformation and calculate curved reinforced concrete beam bearing capacity. These calculations for normally reinforced elements do not considerably differ from the calculations given in the documents. All the main functional dependencies on the calculation stages are visualized.

The paper analyses ways of increasing strength and durability of reinforced concrete matrices for explosive stamping. One of the means to increase the strength of the structure is a technological method of hardening concrete mixture processing. This technique is known as concrete hardening under pressure. The research reveals advantages and disadvantages of this method. It shows that the improvement of matrix characteristics is achieved through engineering changes. The authors describe their design of the matrix, to which they additionally install a compensation layer and a hydraulic chamber. The chamber allows creating pressure inside the structure not only at the moment of its manufacture, but also at any moment of its operation. The paper further describes the developed method of calculating ring-shaped reinforced concrete matrices with a compensation layer. It proposes equations of a matrix and its separate elements motion, necessary for other calculations. The results of calculation of the matrix and its developed structure are described. Graphs of matrix motion and graphs of relative deformations in time done in MathCAD complex are given.

Abstract:The paper presents an improved technique of calculating total deflections of flexural reinforced concrete elements that takes discrete crack formation into account. The technique is based on determining the curvature of the cross section of reinforced concrete elements with cracks and fissures in the area between cracks. The curvature of the element is calculated using a non-linear function of the deformation of concrete under compression. Approximating dependency of concrete resistance on compression developed by one of the authors is presented. An algorithm of finding the curvature and formulas for calculating curvature and deflection are provided. The function of the curvature distribution along the length of a flexible element is proposed by the authors. The paper also presents the results of the author's experimental research. The characteristics of samples tested are described. The experimental research results of deflections of flexural reinforced concrete elements made of conventional and high-strength concretes are presented. Comparison of the values calculated using the technique with those obtained from the experimental research as well as those calculated according to existing regulations in Russia, USA and Europe is drawn.