"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.

Corrosive actions generate degradation of the bearing capacity of reinforced concrete elements of buildings and structures during their operation. Chemical corrosion occupies significant place among this actions. As a result of chemical reactions we evidence the change of mechanical characteristics of concrete and steel. In this paper the investigation of the problem is based on rheological equation of concrete state. In case of one-side contact of concrete with the environment layerwise chemical corrosive damages were educes. The author estimated the influence rate of chemical corrosive damages of concrete on its resistance. The dissipation of energy in compressed zone of corrosive-damaged beam is estimated. This estimation is related to the logarithmic decrement of damping under corrosional damages. The author considers. In the process of resistance of a structural element with a degrading module of total deformations equilibrium is only possible in case of increasing deformations and flexures. Account for this fact is important in the estimation of bearing capacity with the help of deformation criteria.

The article focuses on such buildings as Moscow Central Post Office, State Museum of Fine Arts and GUM. All these buildings were constructed by famous Russian engineer Shukhov V.G. His 160th anniversary is celebrated in 2013.The skylight rectangular in the plan is a covering of General hall in Moscow Central Post Office. It has 3 tiers of glazing. The framework of this tier is a frame structure, which is based on the circumference on the cantilever trusses and, in addition, is hanging on the main trusses of the marquise. The bearing construction of the external lantern consists of ordinary, diagonal and bracing riveted trusses.The covering construction of State Museum of Fine Arts is a combined system, which consists of 2 types of metal trusses. The trusses located under the lamp are of polygonal shape and are bearing constructions for the attic floor, lower and middle glazing contours, as well as for lantern trusses. Lantern trusses of triangular shape serve for attachment of the external glazing contour and areas of metal roofing on the ridge, in the support zones and in the valley.Trading house of GUM has arch translucent covering. Bearing constructions of these coverings are roof arches of circular shape with cross shaped tie beams. Roof boarding was set on the booms made of rolled tees for glazing attachment. Lantern trusses have triangular shape and serve for attachment of an external contour glazing and plots metal roofing on the ridge, in the support zones and in the valley.The article presents the results of examinations, which have been performed by different organizations for the last 30 years.All these buildings are monuments of cultural heritage and they need constant supervision. The covering construction of Moscow Central Post Office needs repair and reconstruction.

Evaporation of the swimming pool water into the indoor air causes penetration of the water vapour containing chlorine derivatives into the enclosure structures and corrosion of the reinforcement due to the presence of dissolved chlorine derivatives in the water. Water vapour migration through outdoor and indoor enclosures is intensive in the cold season, but it may also occur in the warm season. Bearing elements of outdoor and indoor enclosures are now made of the reinforced concrete that has fillers — Portland cement or other types of cement and steel, metal (steel) bars of different diameters. In “ideal” conditions, the concrete must stop corrosion of the steel reinforcement, but it does not happen this way in practice, as corrosion of the reinforcement is influenced by a number of factors.The concentration of chlorides that diffuse into the concrete is lower than the concentration of chlorides in the concrete, but their corrosive influence is higher because of their “non-free” condition. The authors describe the causes and results of corrosion of the steel reinforcement caused by derivatives of chlorine and boosted by the gaseous regime inside the swimming pool building. Analysis of the cases of influence of the water containing 3% of chlorine onto the corrosion of reinforced Portland cement aimed at the reduction of the reinforcement rod diameter is performed. Corrosion of bearing structures causes the loss of strength and durability of buildings, and this process is unsafe from the viewpoint of security of people.

Subject: the article is devoted to the study of corrosion processes in the water supply pipeline network. Initial growth and spatial orientation of corrosive tubercle deposits in non-coated steel pipes were studied. Experimental data are presented and an analysis of conditions and mechanism of formation of corrosive tubercles in water pipes is carried out. An assumption is made about the effect of flow velocity on the formation, growth and spatial distribution of tubercle deposits on the inner surface of the pipe. Research objectives: study of the mechanism of metal pipes corrosion in the water supply systems; development and experimental verification of the hypothesis of formation of tubercle corrosion deposits in pipelines. Materials and methods: the literature data on morphology and composition of tubercle corrosion deposits is analyzed. An experimental study of the initial stage of steel pipe corrosion under static and dynamic conditions has been carried out. Shape and composition of corrosion deposits on the metal surface were analyzed with the help of scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX). The rate of corrosion in a steel non-coated pipe in cold tap water was measured. Results: the study of corrosion sediment shows that its formation and properties are significantly influenced by water flow rate. In the static regime, a uniform distribution of the anode and cathode areas, covered with loose sediment, is observed over the entire area of the sample. In the dynamic mode, the sediment is partially or completely removed from sample surface and the corrosion rate increases. The corrosion process proceeds with oxygen and hydrogen depolarization and contribution of hydrogen depolarization is significant. Over the anodic sections, a dense layer forms with magnetite formation during the cathodic reduction of iron hydroxides. The corrosion rate gradually decreases with time. The presence of sediment on the metal surface slows down the corrosion rate. Conclusions: the conducted studies showed that in the presence of water movement, larger anode and cathode areas are formed on non-galvanized steel pipe samples. These areas, in the course of further corrosion, are transformed into tubercles. Formation of two structural elements of future tubercle deposits was experimentally verified. Water flow velocity, along with the electrochemical processes, is a factor that directly influences the tubercle spatial arrangement and growth on the inner surface of the pipe.