"Вестник МГСУ"

Many Russian and foreign scientists studied in their works bearing capacity of reinforced concrete elements. The principal difference of the presented approaches from the traditional ones is that they lack the necessity of artificial sizing as improbable for simultaneous getting preset limit values of corresponding parameters. In our paper we evaluated the bending moment, giving rise to limit stress strain behavior of corroded reinforced concrete beams with corroded concrete and tensile reinforcement. In order to reduce and simplify calculations we consider single reinforcement and ignore tensile reinforcement resistance, and in order to emphasize the idea of the approach we assume noncorrosiveness. The results of concrete stress strain state analysis are more reliable.

Nowadays, various systems of seismic protection are applied to assure seismic protection of buildings and structures, located in earthquake areas. The greatest prevalence and popularity has been attained by the systems of active seismic protection.In this article, the authors study the efficiency of application of an active seismic protection system by taking high-damping rubber elastomeric isolators as an example. Calculations and their comparative analysis were made for a high-rise reinforced concrete building, and their exposure to the seismic impact was examined. Those calculations were made both with and without the application of the active seismic isolation system. Calculations were carried out by means of the linearly-spectral method using Lira software. Maximum relative horizontal moments arising on the top of the building and forces applied to the elements of walls and columns were compared. On the basis of the results of the calculations and their comparative analysis, the conclusion is drawn that elastomeric isolators may be efficiently applied as an active seismic protection system.

In the article the authors present advanced constructions of prestressed reinforced concrete flat ceiling, where high-strength ropes in elastic shell are used as stressed reinforcement. The novelty of the solution lays in diagonal arrangement of hard valves and use of high-strength ropes in a flexible shell of "Monostrand" type. This type of prestress, in our opinion, is the most acceptable from technical point of view for selective reinforcement of separate tense rods or cables. The use of pre-stressed reinforcement in the form of individual rods or cables increases the rigidity and crack resistance of concrete beamless slabs. The use of high-strength ropes in the monostrand-type shell makes it possible to prestress in frames of single cell plate or floor in general and to reduce labour input for stressing armature. The paper presents original solution with diagonal position of the valve. The authors suggest the use of prestressed diagonal valves as in all cells of the floor with the cells of the same or only slightly different size and in separate cells of the floor (for roofs with different cells). The diagonal location of stressed reinforcement proposed in the work is an efficient solution for extending the range of dimensions and loads size.

In the article, the authors consider heat and mass transfer inside reinforced concrete structures, and their impact on the mechanical properties of the latter.
The authors argue that humidity is an important factor of concrete hardening. As a rule, concrete-to-environment mass transfer, as well as the mass transfer inside concrete products, cause fast dehydration in the course of hardening, thus, leading to the insufficiency of strength. This phenomenon may be exemplified by prefab concrete products hardened in the hot and dry climate. The findings of the authors constitute a simple though efficient solution that consists in the employment of solar chambers equipped with an intermediate, or supplementary, heat carrier. Solar chambers are to be installed inside production premises.
Reinforced concrete products manufactured in accordance with the technology proposed by the authors feature high strength and durability. The concrete structure and properties (namely, compressive strength, tensile strength, modulus of elasticity and cold resistance) even exceed those of the concrete products hardened within 28 days in the regular temperature and humidity environment.
Theoretical principles and experimental research findings of the authors have been invested into the year-round technology of manufacturing of reinforced concrete products inside production premises, where products are treated by the solar energy and a supplementary source of energy. The concrete mix is poured into the form and compacted there; thereafter, the product surface is smoothed. Immediately after that a cover is fixed onto the form and tightly attached to the form walls. The process is to be initiated at 8 a.m. to maximize the period of solar energy consumption and to accelerate the process of concrete hardening.

In the article the information on the upcoming international conference on concrete and reinforced concrete is offered. The aim of the conference is stated, as well as the main points of the program, composition of the conference, the papers’ subject is disclosed. The author highlights the effect of reinforced concrete invention on the world civilization development. According to the author’s point of view, today reinforced concrete became one of the most evident means of the world development.

Some results of high-rise buildings monitoring program are presented in this paper. The monitoring system is currently operating at the high-rise apartment building in Moscow. The vibrating wire strain gauges were embedded in the foundation slab and groundlevel walls during the construction. Measurements are carried out automatically at 6-hour intervals, and received in real time by the monitoring station. In this paper the result of measuring the strain in the concrete walls during 4 years is reported.The computer model of the building was made in order to compare the experimental and predicted data. Mathematical models of a high-rise building are simplified, but we are taking into account the main factors, that influence the stress-strain state of reinforced concrete structures. These factors are: influence of soil base, phases of construction and change of concrete deformation characteristics. The total strain in constructions was calculated as a sum of a strain under load, thermal strain, plastic shrinkage and creep. This data was compared with the total strain in structures measured by the gauges.The analysis of quantitative and qualitative correspondence between the model and actual data was performed. The comparison shows that the theoretical results obtained by the performed procedure are similar to the experimental data. It demonstrates that the model reflects the actual behavior of constructions. The differences found during the comparison are due to the redistribution of stresses from one part of a construction to the other that can occur even if the load is constant. This phenomenon is clearly seen during the suspension of construction. Some differences due to unaccounted factors were found, which should be investigated later.