"Вестник МГСУ"

Subject: studying the main directions for increasing durability and safety of unique, technically complex objects on the example of the Kayrakkum HPP. The peculiarity of operation of this kind of structures is the specificity of physical, chemical and mechanical factors that negatively affect their durability. However, complexity of the technical solution execution does not allow us to completely replace these structures after expiration of their standard service life. Taking into account the uniqueness of the HPP, the programs for the operational suitability restoration are individual. The main problems of reconstruction are considered, which consist in the necessity of, firstly, increasing the station’s productivity, and secondly, ensuring the stability of the dam to erosion and scours. Research objectives: the goal of the study was to develop proposals for improvement of operational suitability of the Kayrakkum HPP based on data on the technical condition of its main units, buildings, and rockfill dam. Materials and methods: in the process of long-term operation, due to filtration processes, seismic influences, the performance parameters of buildings and structures of hydropower plants deteriorate, which negatively affects the reliability of their operation. Therefore, based on the methods of mathematical statistics, data on the projected flood were analyzed. The data on the technical condition of the main HPP equipment were also analyzed and the main directions of its modernization were determined. Results: an assessment of the probability of destruction of the dam showed the need to strengthen it to reduce water filtration. A comparative analysis of possible options for reconstruction of the Kayrakkum HPP has shown the need for an integrated approach that will allow us to solve both the issues of ensuring safety requirements in accordance with international quality standards and enhancement of the plant’s capacity to increase the generation of electricity, the demand for which has increased over time. Out of four technological solutions to reduce filtration into the body of the dam, an option of the central diaphragm from the secant bored piles has been chosen as the least affecting the production cycle of the entire complex. Conclusions: the results of this work can be used when clarifying the repair work organization project to link the technological cycles in such a way as to reduce the losses in generation of electricity caused by execution of works on reconstruction.

Research objective: assessment of the impact of crane loading on safe operation of building by using probabilistic methods; taking into account accumulation of damage in building’s structural elements occurring during operation period. Materials and methods: current computational schemes exploit procedures that do not take into consideration all external effects and changes in structures occurring during operation period of an industrial building. They do not provide algorithms for assessment of spatial response of building’s structures if probabilistic methods are used. Results: the experimental and theoretical research carried out by the author resulted in more precise definitions for computational models and for computational methods of analysis of industrial buildings under the action of various crane loads, including those that are not considered by regulatory documents. The suggested models and methods will enable us to design bearing structures of frameworks in accordance with their real operating conditions. The data obtained in a number of full-scale experiments lead to the conclusion that the amplitudes of vibrations caused by lateral forces when the overhead crane travels with a skew are significantly larger than the amplitudes observed during deceleration of the crane trolley. Conclusions: a hybrid algorithm has been developed; the suggested algorithm implements a complex of procedures for assessment of changes occurring in frame structures under different loading scenarios, during the service life of an industrial building.

The present, globally-applicable revision of the fundamental EN 1990 Eurocode for the design of buildings and civil engineering structures is briefly summarised. General requirements are further elaborated with respect to structural resistance, serviceability and durability. In addition, provisions for robustness, sustainability and fire safety are included. An appropriate level of structural reliability should consider the consequences and possible causes of failure, public aversion and costs associated with reducing the risk of failure. However, the choice concerning the reliability level is left to national interpretation. The target reliability indexes are indicated for one-year and 50-year reference period, with no explicit link to the design working life being provided in the final draft of prEN 1990. It is proposed that the consequences of structural failure be organised into five categories; however, without providing recommendations on the target reliability indices for the lowest and highest consequence class. Supplementary guidance on structural robustness is proposed in prEN 1990, Annex E. A structure should have a sufficient level of robustness that it will not be damaged to an extent disproportional to the original cause. The working life design should be considered for time-dependent performance of the structures. Ultimate and serviceability limit states should be verified for all relevant design situations. Apart from the commonly-used partial factor method, which comprises a basic method for structural verification, additional guidance is also given for application of non-linear methods. The partial factors have been newly-calibrated with the aim of achieving a more balanced reliability level for structures from different materials and loading effects.

Considers the modern building envelope construction with outside skin used as a sun shields. Such a constriction is often used for buildings with low energy consumption. A number of factors besides sun radiation influencing on the performance of facade system in general and every certain parts and elements throughout the entire period of building operation. Subject: multilayer and double skin building facades and sun screens located on their surfaces. Including, dual-use facades combining functions of the sun screen and sub construction for the placement of photovoltaic cells. Materials and methods: the main method was an estimation the aerodynamic and air-thermal characteristics of a double skin façade. Was considered a construction with combined function of a sun shield. The method was previously used in evaluation of the air-thermal regime of hinged facade systems of buildings for cold period of a year. The general approach was advanced and verified by the results of full-scale tests of building facades in the warm period of the year. Results: indicates great influence of air and thermal conditions of air gap in double skin and similar construction facades on performance of façade system in general and on every certain part of it. Conclusions: the construction of complex facade systems with the use of up to date technologies requires additional study of the air-thermal conditions of the air gap between the main facade of the building and its second skin or sun screen. Ignoring the operational features of active sun shields under extreme loads can lead to a decrease in the equipment functionality and its premature failure.

The present article deals with integrated research works and tests of pipeline supports for the areas of above-ground routing of the pipeline system “Zapolyarye - Pur-pe” which is laid in the eternally frozen grounds. In order to ensure the above-ground routing method for the oil pipeline “Zapolyarye - Pur-pe” and in view of the lack of construction experience in case of above-ground routing of oil pipelines, the leading research institute of JSC “Transneft” - LLC “NII TNN” over the period of August, 2011 - September, 2012 performed a research and development work on the subject “Development and production of pipeline supports and pile foundation test specimens for the areas of above-ground routing of the pipeline system “Zapolyarye - Pur-pe”. In the course of the works, the test specimens of fixed support, linear-sliding and free-sliding pipeline supports DN1000 and DN800 were produced and examined. For ensuring the stable structural reliability of the supports constructions and operational integrity of the pipelines the complex research works and tests were performed: 1. Cyclic tests of structural elements of the fixed support on the test bed of JSC “Diascan” by means of internal pressure and bending moment with the application of specially prepared equipment for defining the pipeline supports strength and durability. 2. Tests of the fixed support under the influence of limit operating loads and by means of internal pressure for confirming the support’s integrity. On the test bed there were simulated all the maximum loads on the support (vertical, longitudinal, side loadings, bending moment including subsidence of the neighboring sliding support) and, simultaneously, internal pressure of the carried medium. 3. Cyclic tests of endurance and stability of the displacements of sliding supports under the influence of limit operating loads for confirming their operation capacity. Relocation of the pipeline on the sliding supports from temperature expansion in case of preheated oil charge into a “cold” pipeline was simulated. 4. Cyclic tests of durability of frictional couples under the influence of operational and maximum loads. On the test bed there were examined various materials for the sliding surface of the supports, ensuring the norm friction coefficient.

Criteria of plasticity and durability derivative of standard indicators of plasticity (δ, ψ) and durability (σ
_0,2, σ
_B) are offered. Criteria К
_δψ and К
_s follow from the equation of relative indicators of durability and plasticity. The purpose of the researches is the establishment of interrelation of derivative criteria with the Page indicator. The values of derivative criteria were defined for steels 50X and 50XH after processing by cold, and also for steels 50G2 and 38HGN after sorbitizing. It was established that the sum of the offered derivative criteria of plasticity and durability С
_к considered for the steels is almost equal to unit and corresponds to a square root of relative durability and plasticity criterion C
^0,5. Both criteria testify to two-unity opposite processes of deformation and resistance to deformation. By means of the equations for S
_к and С it is possible to calculate an indicator of uniform plastic deformation of σ
_р and through it to estimate synergetic criteria - true tension and specific energy of deformation and destruction of metal materials. On the basis of the received results the expressions for assessing the uniform and concentrated components of plastic deformation are established. The preference of the dependence of uniform relative lengthening from a cubic root of criterion К
_δψ, and also to work of the criteria of relative lengthening and relative durability is given. The advantage of the formulas consists in simplicity and efficiency of calculation, in ensuring necessary accuracy of calculation of the size δ
_р for the subsequent calculation of structural and power (synergetic) criteria of reliability of metals.

This study addresses the development of ultra-lightweight concrete. A moderate strength and an excellent thermal conductivity of the lightweight concrete are set as the design targets. The designed lightweight aggregates concrete is targeted to be used in monolithic concrete façade structure, performing as both load bearing element and thermal insulator. The developed lightweight concrete shows excellent thermal properties, with a low thermal conductivity of about 0.12 W/(m·K); and moderate mechanical properties, with 28-day compressive strengths of about 10-12 N/mm
². This combination of values exceeds, to the researchers’ knowledge, the performance of all other lightweight building materials. Furthermore, the developed lightweight concrete possesses excellent durability properties.

In order to prolong the lifetime and to improve the quality of pavements made of asphalt concrete it is necessary to apply innovative solutions in the process of design of such building materials. In order to solve the problem of low durability of asphalt concrete a modifier was proposed, which consists of diatomite, iron hydroxide sol (III) and silica sol. Application of the diatomite with nanoscale layer of nanomodifier allows getting a stone mastic asphalt, which has high values of physical and mechanical properties and allows refusing from expensive stabilizing additive. Mineral filler was replaced by diatomite, which has been modified by iron hydroxide sol (III) and silica sol. Modified diatomite allows sorption of bitumen and increase the cohesive strength and resistance to shear at positive temperatures. The modified asphalt has higher resistance to rutting at high temperature, abrasion resistance at low temperature and impact of climatic factors: alternate freezing and thawing, wetting-drying, UV and IR radiations. It is achieved by formation of solid and dense bitumen film at the phase interface and controlling the content of light fractions of the bitumen. The modifier consists of sol of iron hydroxide, which blocks the oxidation and polymerization of bitumen during operation. The proposed material allows controlling the initial structure formation of stone mastic asphalt. It was shown that modern test methods allow assessing the durability of asphalt in the design phase compositions.

The objective of the research project was to design multi-component concrete with an optimized pore structure designated for sewage water treatment facilities. It was followed by the study of their stability in aggressive environments. Measurement of mesopores and macropores with diameters of 0.0055 to 360 mcm was taken using AutoPore IV 9500 porosimeter. X-ray analysis of samples was performed using diffractometer ARL X’TRA produced by Thermo Scientific (Switzerland). Modified 28-day concrete cubes were exposed to aggressive environments for 1 year at low (+4 ± 2 °C) and high temperatures (+20 ± 2 °C) to identify their linear deformation characteristics. Compressive strength of samples was tested upon completion of each three-month period.The authors have found out that degradation of concrete samples in the corrosive environment of waste waters accompanied by generation of thaumasite is less intensive than that in the waste waters that have ettringite generated. Thus, the authors have discovered that the lower the temperature of the aggressive environment of the waste water, the more intensive the formation of ettringite that causes destruction of the concrete. Optimization of the concrete structure is attained through the optimization of the concrete composition. Application of fine-grained silica causes generation of concrete that is highly resistant to the aggressive effects of sulfates and chlorides.

The authors consider the problems of influence of corrosive water media onto underground buildings and structures and various methods of their waterproofing. The market overview of up-to-date waterproofing compounds is provided in the article. The authors set forth their research findings identified at Moscow State University of Civil Engineering recently. A new mineral-based waterproofing coating material is presented. The authors deal with the issue of chemical interaction within the system of cement - microsilica - soda-silica glass and the issue of optimization of particle packing aimed at the assurance of superior protective and durability-related properties of the composition. The main process strengths of the new coating material are enlisted.The authors introduce the results of comparative tests of basic hydro-physical and mechanical (compressive strength, adhesive strength) properties of the new material and its analogues currently applied in the construction industry with a view to the assessment of the protective ability and the economic effectiveness of the new waterproofing material.

Effectiveness of thermal insulation products is determined by a set of criteria that can be expressed in terms of energy costs: reduction of the cost of heating (the main criterion), energy consumption in the course of construction, energy consumption in the course of production of materials having pre-set properties, and service durability of the material.On the one hand, service durability (as a property) is generated in the course of material production, and on the other hand, it depends on the conditions that the material is exposed to in the course of any construction process. The same parameter affects energy-related criteria. Insulation replacement or unplanned repairs add supplementary energy costs.The manufacturing process of thermal insulation materials contemplates processing of a significant amount of non-renewable natural resources, namely, fuel combustion. Optimization of these costs is necessary and possible through appropriate organization of processes, including the process of heat treatment of products.Layered materials can improve the product performance and durability. Production and heat treatment of mineral fibers are the most energy-consuming steps of the mineral wool production. Optimization of these processes can involve significant economic effects.

This article covers the design of an advanced multi-component additive and the study of its influence produced on the properties of fine-grained concrete. The authors also provide data on the earlier studies of the effect produced by domestic superplasticizers on the plasticity of fine-grained concrete mixtures and the curing behaviour of plasticized fine concretes. Russian-made superplasticizer Khimkom F1 was used to retain the plasticity of the fine concrete under consideration. Khimkom F1 produces a better effect on concrete curing than Polyplast SP-1, Cemactive SU-1, and Linomix SP 180-2. Superplasticizer Khimkom F1, as opposed to plasticizers based on lingo-sulfonate or naphthalene, for example S-3, has no bad odour; it is non-corrosive if applied to steel reinforcement inside concrete. The research has proved that the optimal amount of Khimkom F1 is 1.2% of the total amount of the binder.Metakaolin fume was used to improve the microstructure of the concrete, including its strength, waterand frost-resistance. Improvement of the above properties was proved in the course of the experiment. Its optimal content equals to 15% of the total amount of the binder. The study of the two domestically made water repellents (Sofexil40 and Sofexil 60-80) was conducted to identify and to compare their water and frost resistance. Experimental findings have proven that Sofexil 40 produces higher influence on the properties of the fine concrete, used for hydraulic engineering purposes, than Sofexil 60-80. The optimal content of the water repellent is 0.2% of the binder content. Sofexil 40 must be dissolved in the water in advance. Finally, the authors provide their experimental findings in terms of the optimal composition of the fine hydraulic concrete having pre-set properties.

Dry construction mixes are today a product of high technologies. Depending on the purpose and requirements to the properties it is easy to produce dry construction mixes with different compositions and operating indicators in plant conditions using the necessary modifying additives. Cement, gypsum and other mineral binders are used in the construction mixes. Different types of cement are more heavily used in dry construction mixes. Such dry mixes are believed to be more effective materials comparing to traditional cement-sandy solutions of centralized preparation. The authors present the results of the investigations on obtaining biocidal cement-sand compositions. It was established, that introduction of sodium sulfate into the composition provides obtaining the materials with funginert and fungicide properties. The strength properties of the mixes modified by carbon nanotubes and biocide additive were investigated by mathematical planning methods. The results of the investigations showed that the modification of cement stone structure by carbon nanotubes positively influences their strength and technological properties. Nanomodifying of construction composites by introducing carbon nanotubes may be effectively used at different stages of structure formation of a construction material.

The use of thermal insulation materials is an effective method to create an insulating envelope of a building, as well as to reduce energy costs and increase the durability of building structures. The properties of stone wool products and their operational durability is largely determined by the conditions of formation of the mineral wool carpet, uniform distribution of binder and its curing and the heat treatment conditions. Most domestic technologies are aimed at the production of mineral wool products with volume-oriented structure, which is formed using special units: spreader and corrugator placed in a production line. The next step to obtain the optimum structures is the production of dual density slabs. The denser upper layer receives mechanical loads caused by the operating conditions; the lower, less dense, but more thick layer performs the main function - insulation. The dual density slabs are produced on standard lines supplemented with a special unit, which is located in front of the heat treatment camera. Optimization of heat treatment parameters and prediction of the properties of materials is performed using software package.

The article studies the effect of ultraviolet radiation, salt fog, variable humidity, and sea water of the Black Sea coast of Krasnodar region near the village of Abrau-Durso on the basic physical and mechanical properties of asphalt: the average density, water saturation, tensile strength at 122 °F, 68 °F and 32 °F, on the waterproofing quality of asphalt concrete. The samples were exhibited on a pier and in the soil on the coast of the Black Sea, in the sea water and in the air 400 m away from the sea. Test specimens were manufactured in accordance with Russian State Standard GOST 12801-98. Test duration was 240 days. It is found out that sea water has a negative effect on the majority of physical and mechanical characteristics of asphalt concrete. The authors found the compositions of asphalt concrete with increased resistance to the influence of climatic factors. Higher resistance is achieved in the case of dense asphaltic concrete ballast.

This paper considers and asserts the need to obtain the results of inspection of a building at the stage of its commissioning in order to apply comprehensive methodology for assessing its residual life. The author proposes to build regression relationship by correlating the levels of the time series dynamics of stress at certain points of the object calculation scheme considering the results of subsequent surveys. It allows estimating the wear rate of structural elements. The assessment of the reliability and durability of the building frame in a deterministic form is based on the limit states method. The application of this method allows taking into account the random nature of not only the combination of existing loads, but also the strength properties of construction materials by creating a system of safety factors.

Introduction. Monuments of wooden architecture - an invaluable part of the national culture, they reflect the originality and independence of the national architecture. The problem of preservation of monuments of wooden architecture with the passage of time is becoming increasingly important. Many monuments were burned; some were destroyed due to the loss of structural strength under the influence of humidity, biodestruction, etc. Materials and methods. The samples of partially destroyed wood of the Anglican Church of the city of Arkhangelsk, built in 1833, were studied. The samples were subjected to surface modification with the formation of a two-layer sandwich coating, the first layer of which was various phosphorus-containing flame retardants, and the second layer - polymer composites. As polymer composites, glue based on epoxy resin and polyurethane composition “Akvidur TT” were used. The reactive organophosphorus compounds, capable of forming covalent bonds with wood polymers in the surface layer of partially destroyed wood, were chosen as flame retardants. Modified samples were subjected to physicochemical studies to determine the strength, fire resistance, hydrophobicity. The strength of the modified samples was compared with the strength of the untreated samples of partially destroyed wood of the Anglican Church of Arkhangelsk. The appearance of covalent bonds between the wood and the modifier was determined by Fourier-transform spectroscopy. Results. Surface modification of the samples of the monument increased the strength of wood by 2-2.5 times, reduced water absorption by 3 times, reduced the loss of mass during combustion according to GOST 27484-87 to 5.0-6.4 %. Conclusions. The study solves the urgent problem of preservation of monuments of wooden architecture by increasing the strength of partially destroyed wood, as well as giving it fire resistance, hydrophobicity and biostability in carrying out restoration work.

Subject: interaction of the moving vehicle with asphalt concrete road pavement. Research objectives: analysis of influence of dynamic loads from the moving vehicle on the road pavement with asphalt concrete. Materials and methods: interaction models are based on the impulse approach (impulse of dynamic loads) and dynamic factor. Results: creation of the mathematical model which is based on the impulse approach and allows us to determine the load on the pavement as a function of vehicle speed. Conclusions: 1) when the speed increases, the force exerted by the moving vehicle on pavement quickly decreases, reaching a minimum at some speed, and then slowly increases; 2) there exists the optimum vehicle speed for the highway exploitation, at which the impact of the force on the road is minimum; it is possible to increase the pavement longevity if this speed for road exploitation is complied with.

Introduction. The paper presents theoretical and experimental studies of the improvement of the structure of lightweight concrete, which provides the maximum value of the attenuation of the amplitude of external air temperature fluctuations during the passage of heat flow through the walls and the reduction of thermal conductivity, the results of the 3-factor experiment on determining the rational structure of claydite concrete and the methods for their processing. To determine the purposeful structure of the composition of lightweight concrete and its thermal conductivity, a complex of research works was carried out at the Central Research Institute for Housing, applied to lightweight concrete for exterior walls. The main optimization criterion was the maximum reduction in thermal conductivity while providing the necessary strength, durability and waterproofness. The purpose of this work is theoretical research and experimental substantiation of methods for improving the structure of lightweight concrete used for a hot climate with improved functional performance. Materials and methods. As material a claydite gravel with bulk density p = 400 kg/m3 of Lianozovsky plant (Moscow) was used, at a ratio of 40 % of the fraction 5-10 mm and 60 % of the fraction 10-20 mm and a Portland cement of the brand “400” of the Voskresensky plant, not plasticized. The water flow rate was varied for 10 seconds, to ensure the mixture to be vibropacked.As a foam generating agent and plasticizer, the “Saponified wood resin” (SDO) was used in a 5 % aqueous solution. The methods were adopted in accordance with the Recommendation on the technology of factory production and quality control of lightweight concrete and large-panel constructions of residential buildings. M. CNIIEP dwelling, 1980. In the department of the lightweight concrete application at CNIIEP of dwelling, a method for the purposeful formation of the structure and composition of lightweight concrete, which provides a set of physic-technical, technological and technical-economic requirements, was developed. Results. Calculations are reduced to obtaining mathematical models of dependence of strength R, density ρ, thermai conductivity λ and other indicators of concrete characteristics from initial factors in the form of regression equations. Based on the equations obtained, it was possible to determine the expedient composition of lightweight concrete, which, in combination with the operational characteristics, provides comparable results of the technical and economic characteristics of a single-layer structure from the projected type of lightweight concrete. Conclusions. 1. An improved composition of the structural and heat insulating lightweight concrete for the load-bearing part of the structure, providing its high thermal stability by chemical additives and low consumption of porous sand, was developed. An algorithm for selecting its composition on computer is made. 2. The conducted researches in the field of design of external enclosing structures for hot climate conditions have shown that: single-layer exterior wall constructions with massiveness of D ≤ 4 provide minimum allowable values of heat flux attenuation and temperature fluctuation amplitude on the inner wall surface.