Reinforced concrete structures can be exposed to aggressive environmental influences, which leads to a decrease in their bearing capacity during their service life. If a safety assessment of such structures is to be carried out in order to be able to continue in service, the main challenge would be to ensure that they can withstand future extreme loads over their intended lifetime with a level of reliability sufficient for safety.

There are currently no methodologies for such an assessment.

This methodology is proposed to facilitate quantitative assessments of the current and future structural reliability and load-bearing capacity of reinforced concrete structures. This methodology takes into account the random nature of past and future pressures, as well as degradation as a result of negative environmental factors.

The time-dependent reliability and deterioration assessment of reinforced concrete structures provides the basis for determining the duration of safe operation.

An estimated estimate of the long-term operation of a reinforced concrete beam on a ground base is presented, taking into account environmental and dynamic force effects. A method of dynamic calculation of reinforced concrete structures of structures of various types on a ground base operated in an aggressive environment is proposed, internal factors of rheological deformation are also taken into account, taking into account corrosion damage, reflecting their real work under the joint action of the load and the aggressive environment on the basis of the modern phenomenological theory of deformation of the elastic creeping body. It is shown that corrosion damage to reinforced concrete elements can affect the strength of the material, change the calculation schemes, redistribute forces in the cross-sections of the structure and disrupt the joint operation of concrete with reinforcement, as well as lead to other consequences that reduce the design time of operation of structures and other operational characteristics. The possibility of modeling the processes of deformation of reinforced concrete under conditions of long-term operation with a changing mode of action of an external load is shown. An example of the calculation of a reinforced concrete flexible foundation on a soil base is given for the considered service life and the presence of corrosion damage.

Civil defense structures are exposed to short-term dynamic loads of high intensity. In order to reduce dynamic forces and movements of structures, active methods of protection, which include yielding supports, have been increasingly used in recent years. In this paper, the assessment of the influence of the yielding of supports is carried out based on the results of the calculation of reinforced concrete beams on yielding supports under short-term dynamic loading. The work of the structure is considered in the conditionally elastic stage, and yielding supports in the elastic, plastic and hardening stages. Collapsible inserts of an annular profile are accepted as yielding supports. For reinforced concrete beams on yielding supports, the equation of motion, function and coefficient of dynamism are determined. It has been established that the use of elastic yielding supports can have both positive and negative effects on the operation of structures, which is expressed in the excess of forces and displacements of structures on elastic supports relative to elements on non-displaceable supports. When yielding supports are deformed in the elastic and plastic stages, there is a sharp decrease in the dynamic coefficient of beams, and, consequently, stresses and deformations in structures. The transition of yielding supports to the stage of hardening leads to a sharp increase in the dynamic coefficient of the structure.

Asymmetric arrangement in the plane of vertical bearing elements, ladders, stiffness elements is to the occurrence of eccentricity between center of rigidity and center of mass. Later, under the action of a horizontal load, torsion occurs in asymmetric load-bearing systems. This paper considers the resistance of multi-storey buildings during torsion caused by an asymmetric arrangement of vertical load-bearing objects.

The object of the study was the carrier system of a residential monolithic multi storey building with an implicitly non-coinciding center of rigidity and center of mass. Numerical simulation for a horizontal load determined the stress-strain state of vertical reinforced concrete structures. The change in forces and displacements in the pylons during the torsion of a multi-storey building is obtained. The results of the analysis carried out can be used in the design of compressed and bending reinforced concrete structures subject to torsion.

The impact of aggressive environments and, accordingly, the corrosion damage of concrete and reinforcing steel, the violation of adhesion between them in some areas lead to a change in the values of the limiting height of the compressed zone, which determine the plastic or brittle mechanism for the destruction of structures of reinforced concrete frame buildings. The purpose of the presented study was to assess the influence of the depth of corrosion damage on the ultimate height of the compressed zone of the section of eccentrically compressed elements of reinforced concrete frames of buildings, as well as to assess the bearing capacity of these elements. The article presents analytical dependences for estimating the limit value of the height of the compressed zone of the section of a corrosion-damaged reinforced concrete element of the building frame with a two-line approximation of the state diagram of concrete.

It has been established that an increase in the depth of corrosion damage leads to a decrease in the height of the compressed section zone relative to the part of the working height of the section that retained the resource of force resistance, as well as to a decrease in the bearing capacity of eccentrically compressed reinforced concrete elements due to a decrease in the effective working height of the section and an increase in their flexibility. An increase in the flexibility of the elements leads to a decrease in the magnitude of the limiting longitudinal force perceived by eccentrically compressed reinforced concrete elements. At the same time, an increase in the relative depth of corrosion damage enhances this effect due to an increase in the effective flexibility of such elements compared to elements without damage.

The article discusses the features of the structure of concrete in a structure made using additive technology (3-D printing). The result of the formation of the structure when using the 3-D printing method is investigated. According to the results of experimental studies, the features of the formation of the concrete body of the structure performed using additive technology are revealed.

The features of the concrete structure formed in the concrete body when using additive technology are established. The results obtained can be used in the development of methods for experimental studies of effective mechanical characteristics of concrete, as well as in studies to determine the coefficients of concrete working conditions in structures made using additive technology.

The article considers the structure of regulatory documents for precast reinforced concrete structures. The directions of development of the regulatory framework by updating and developing standards (GOST and GOST R) for certain types of precast reinforced concrete structures are given. It is noted that the purpose of the development and updating of standards is to establish current technical requirements for precast reinforced concrete structures, due to changes in the regulatory framework for the design of reinforced concrete structures, in particular in SP 63.13330.2018 "SNiP 52-01-2003 Concrete and reinforced concrete structures. The main provisions", and the improvement of technological requirements. In recent years, JSC "Tsniipromzdaniy" has developed and updated more than 20 standards (GOST and GOST R) only by the Department of Structural Systems No. 1, in which a number of new provisions have been adjusted and developed based on the analysis of domestic and foreign regulatory framework, modern manufacturing and installation technologies. It is advisable to develop standards for individual structures taking into account the requirements given in the fundamental GOST 13015-2012 "Concrete and reinforced concrete products for construction. General technical requirements. Rules of acceptance, marking, transportation and storage". The structure of the standard standard for precast reinforced concrete structures is considered.