One of the main components of the economic development of the Russian Federation is the current trend in the development of the territories of the Far North and the Arctic. The need for such development is enshrined at the state level in various programs. Experiments on the study of the effect of negative temperatures on the operation of reinforcing steel show that with decreasing temperature, an increase in strength and modulus of elasticity is observed. At the same time, there are no unified recommendations on the deformation and strength properties of reinforcement for calculating reinforced concrete structures under conditions of low and ultra-low negative temperatures. RF standards do not take into account the influence of climatic (up to -70°C) and technological (up to -196°C) negative temperatures on the deformation and strength characteristics of reinforcing steel.

The purpose of this work was to experimentally study the effect of negative temperatures (up to -196°C) on the deformation-strength properties of reinforcement, concrete and reinforced concrete rod elements. Concrete prisms 10x10x40 cm, samples of reinforcement of a periodic profile of class A400 and reinforced concrete prismatic rods with a section size of 12x18 cm and a reinforcement percentage of 1.45% were taken as prototypes. At the same time, the negative temperature of the tests varied. As a result of the studies carried out with centrally stretched reinforced concrete elements, it was found that lowering the temperature to -165°С leads to an in-crease in the cracking force by 162%; strength by 85%. Empirical dependencies are proposed to determine the deformation-strength characteristics of reinforcing steel, depending on the negative temperature.

The article discusses the issues of reliability for various types of failures of beam systems. A single-span bending beam is analyzed. The limit state functions for moment failure modes in the characteristic sections of the beam are determined. The ways of forming a plastic hinge for a beam are shown. The lower and upper limits of the beam reliability are calculated. Limit state functions corresponding to failure mechanisms are presented.

This paper presents the history of the development of the method for calculating the crack resistance of reinforced concrete elements according to Soviet and modern design standards, which was based on the work of the Soviet and foreign scientists, such as: A.F. Loleit, V.I. Murashev, A.A. Gvozdev, S.A. Dmitriev, A. Clark, J. Monier and others. Also, the article discusses the currently updated calculation methods for the formation and opening of normal cracks according to domestic and foreign standards.

The article deals with the issue of estimating the strength and stress-strain state of a reinforced concrete shell by the method of membrane theory and the theory of infinitesimal bending. A brief description of the methodology consists in the fact that the ground stress state of the shell is allocated to an independent problem, when, without introducing boundary effects, two of the four boundary conditions of the general moment theory are distinguished, which, together with the equations of the momentless theory, determine the ground stress state, and then boundary effects are superimposed. The equilibrium equations of the moment theory in forces and moments, geometric equations, components of tangential deformation and displacement, and the physical equations of state connecting them, expressing forces and moments through the components of deformation, are presented, since the characteristics of the stress-strain state of the shell depend not only on the variability of external influences and forces, but also on the length of the structure. The provisions laid down in the article shall be retained in the case of casings made of anisotropic material, provided that the presented elastic ratio is met. A system of equations of the generalized semi-membrane (semi-bending) state of an arbitrary shell of zero curvature, which determines the accuracy of this approach, is solved. The equations of the semi-torque theory for a circular cylindrical shell are presented, as well as describing the semi-membrane stress state of a long shell of zero curvature. The most important result of the study is the method of constructing integrals of the ground stress state of the shell based on the method of simple iterations, which expands the possibilities of the reliability theory, which makes it possible to build the foundations for the practical calculation of reinforced concrete shells according to the membrane theory and the theory of infinitesimal bending.

The article presents a calculation of rubber-metal vibration isolators with five holes of different diameters using a software package that implements the finite element method. A comparative analysis of the Eigen frequencies of rubber-metal vibration isolators with five holes (one in the center, 4 symmetrically at the corners) and without holes is presented. Finite element models of a rubber-metal vibration isolator with and without holes are modeled, and their characteristics are analyzed. The results show that vibration isolators with several symmetrically located holes have several advantages in a number of parameters to vibration isolators without holes, and, therefore, can be used for vibration isolation of buildings, especially in the case of delayed installation of vibration protection.

Analytical, computer and experimental modeling methods are applied in the study of seismic resistance and changing dynamic parameters of long-term loaded non-linearly deformed large-span spatial shell structures. Physically and geometrically nonlinear deformation models and computational algorithms for solving dynamic problems are proposed for estimating the stress-strain state of smooth and ribbed spatial systems with variable stiffness caused by damage accumulation and orthotropic structure reinforced by ribs. The possibility of using the proposed method of taking into account variable dynamic stiffness in calculations for solving problems of dynamic strength and stability of spatial large-span shells of unique buildings of complex geometry is shown.

The construction of a mathematical model based on the finite element method for determining the stress-strain state of a 25-storey reinforced concrete building on a multilayer deformable foundation is considered. 

The sensitivity of the physical and mechanical characteristics of the building and foundation material to the type of stress state, the development of plastic deformations in reinforcement, damage in the form of cracking, and induced heterogeneity are taken into account. The relations for nonlinear isotropic materials proposed in the frame-work of the theory of normalized stress spaces are taken as constitutive relations. A modification of a multilayer triangular hybrid finite element with five degrees of freedom in the node is formulated to describe the features of the mechanical behavior of building structures. A description is given of methods for modeling fictitious layers of an element corresponding to various variants of the stress-strain state of reinforced concrete. Quantitative estimates of the stress-strain state of the combined "building-base" system under the action of static loads of two types are obtained in the form of graphs of the dependence of dis-placements on the magnitude of the load in floor slabs and pylons. According to the results of the research, it was confirmed that taking into account "complicated" ones is necessary to obtain correct estimates of the stress-strain state of buildings.

This article outlines the main provisions in the design of an acoustic reverberation chamber, methods for modeling such objects in engineering and construction practice. A finite element model of an object is presented in the Midas FX software package. 

As a result of the calculation, it is possible to evaluate the components of the stress-strain state in concrete and in structural elements or on the contact surface, the effect of vibration loads on RAC structures, their interaction with the foundation and soil base, as well as analysis of the use of vibration isolators in the RAC foundation Based on the results of the analysis, recommendations are given for perform calculations of system elements, select design solutions.

The article presents a brief analysis of the experience of developing standards for the design of reinforced concrete structures in the Republic of Belarus. The principles on the basis of which these norms were developed are considered. The advantages and disadvantages of using European design standards EN 1992-1-1 of various generations, as well as fib Model Codes are shown.

In this article, the authors present the results of a study of unreinforced and reinforced stone vaulted ceilings, which included numerical and physical experiments. We have also developed our own constructive measures to strengthen stone vaulted ceilings, based on the introduction of composite flexible rods into the body of the luggage in optimal places and, in turn, allowing to increase the efficiency and safety of work. The article presents the process of creating a homogeneous and heterogeneous model, which made it technically possible to solve problems with modeling reinforcement in masonry.