Строительство уникальных зданий и сооружений @unistroy
Статьи журнала - Строительство уникальных зданий и сооружений
Все статьи: 849
Radiant heating and cooling systems based on capillary micro tubes
Статья обзорная
Radiant heating and cooling systems based on capillary micro tubes have been gaining much popularity due to large operational area, space saving, small difference between temperatures of flowing water and air inside the room and consequently improved energy efficiency. The objective of this review is to find out fields of applying capillary micro tubes, to discover advantages and limitations and analysis of future development. Based on research results it can be concluded that heating system based on capillary mats is an effective and promising solution for residential and public buildings.
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Статья научная
Changes in the existing urban structures that result in obsolescence and abandonment of buildings open up the opportunities for an alternative use of the existing building fund that would be in line with the current needs and aspirations of today. Conversion of obsolete buildings to residential buildings might be an optimal solution for the social and demographic changes that continuously influence and intensify the demands for new housing. The paper points out the quality of this approach and explores the extent to which conversion of obsolete buildings for residential uses may be a valid tool in sustainable development strategy.
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Recreation of the historical site ornamental ponds “figurnye prudki”
Другой
The objective of this paper is reconstruction of a part of the Oranienbaum Palace-and-Park Ensemble, Saint-Petersburg, Russia, the conventional name of the part is ‘Figurnye Prudki’. At present Russian Federation have quite a few palace-and-park estates, landscape architecture monuments, which today are in a bad repair or breakdown state. The Figurnye Prudki site is one of such monuments, therefore recommendations containing in this article for the recreation of the property seem to be relevant.
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Reducing utility bills through the introduction of energy efficient systems
Статья научная
The object of the study is an improved system for the partial recovery of the condensation heat of refrigeration machines, its development, implementation and study of operational performance, which increases the share of waste heat in the air heating system in order to increase their energy efficiency and optimize operating costs. The purpose of this work is to analyze the costs of using heat to heat the coolant in the air heating system from the heat supply organization, with the costs in case of heating the coolant in the condensation heat recovery system. Method. To analyze the calculated and actual values, the development and implementation of a research stand based on an ultrasonic flow switch and a heat meter was carried out, which made it possible to evaluate the economic effect of the implementation of the proposed solutions. Results. With regard to the air heating system of buildings with artificial freezing of the ice surface, the economic effect in the form of a reduction in utility bills for heating is 2.46 million rubles per year, while reducing the thermal pollution of the environment by at least 1.4 GW.
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Renovation of apartment buildings in Russia
Статья научная
The existing housing stock of the Russian Federation makes 3.6 billion m2 (2016). The area of apartments is about 25 m2 per one person. About 50% of houses in Russia need renovation. The considerable part of housing stock was constructed during an era of industrial housing construction. Many buildings of the first mass series have high strength characteristics. However, thermal comfort of these buildings in most cases unsatisfactory. Taking into account that the heating season in Russia on average lasts from October until April, the specific heat consumption for heating and ventilation during the cold period is 150—200 kWh/m2 per year for non-modernized buildings. This paper demonstrates the results of the investigations based on the field study and calculations of the thermal performance indicators of the standard residential building made of many box units (HDD = 3925 K*day/year). According to calculations, after thermal modernization of buildings the level of specific heat consumption for heating and ventilation will decrease twice...
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Seismic shear design of twenty-story RC building with ductile wall system
Статья научная
This paper presents analysis of seismic shear design of twenty-story RC building designed in accordance with EN 1998-1. For this analysis, uncoupled ductile wall system is selected as structural system of building. Preliminary seismic analysis of structure is carried out using modal response spectrum analysis. The nonlinear time-history analysis is performed on the spatial model of the structure where the structure is exposed to seven real earthquake records selected in accordance with the rules defined in EN 1998-1. The subject of performed nonlinear time-history analysis is seismic shear design of DCH ductile walls in accordance with EN 1998-1. The analysis of determining design shear forces using magnification factor and analyses of diagonal compression and diagonal tension failure of the web due to shear for DCH ductile walls are performed. Based on the derived results, corrections for the magnification factor and for shear resistance of ductile walls are proposed. The analysis leads to conclusions regarding the design procedure for "large" ductile walls (L=6.0m), walls that accept the dominant part of seismic force, in relation to the "small" walls (L=3.0m), walls in which minimum reinforcement is relevant.
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Self-healing concrete using fly ash, macro synthetic fibres and recycled aggregates
Статья научная
The development of cracks in concrete can reduce its durability and service life, causing its steel rebar to be exposed to harmful substances from the external environment, eventually leading to strength loss of concrete and high repair costs. Self-healing technique can eradicate the crack spontaneously, likely replacing or decreasing maintenance and repair costs. Self-healing concrete using low calcium Fly Ash with recycled Aggregate (RCA) and macro synthetic fibers is a novel approach to increase durability and serviceability, decreasing repair and maintenance costs. This research intends to create self-healing concrete using different volumes of Fly Ash with partially replaced RCA and macro synthetic fibers and to study the autogenous behavior of Fly Ash. Various volumes of Fly Ash 35%,45%, and 60%, respectively, were used. In addition, the coarse Aggregate was partially replaced with RCA. The results show that replacing RCA with natural Aggregate and using Fly Ash significantly decreased the strength of concrete. Thus, to increase the mechanical properties of concrete macro synthetic fibers were used at two percentages 5% and 1%, respectively. After that, concrete samples were cracked after 28 days of curing, and after 5 weeks, they were cured for autogenous self-healing. The results showed that using Fly Ash from 45-50% gave the optimum healing to cracks in 5 weeks and the use of macro synthetic fibers at 0.5% caused the best improvement in mechanical properties of concrete with good workability.
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Shape memory polymer rods for improving crack resistance in reinforced concrete beams
Статья научная
The object of research is reinforced concrete beams with combined reinforcement. The improvement of their crack resistance is essential because crack propagation reduces the durability of structures, and conventional methods of crack closure are not always effective. Method. The study employs an experimental method involving four-point bending tests on specimens with additional heat-activated polycaprolactone rods. Results. The study found that after heat activation, the crack width in the modified beams was more than halved compared to control specimens, and the deflection value decreased by 16%. These results demonstrate the potential of using shape memory polymer elements to control the deformation state of reinforced concrete structures and improve their performance.
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Статья научная
The object of research is the nature of deformation of flexural elements made of high-strength concrete, reinforced with classical bar and sheet reinforcement, under long-term loads. The relevance of the work is determined by the lack of data on the deformation characteristics of such structures in regulatory documents and scientific literature; this applies both to short-term loads and especially to long-term ones. Such experiments have not been conducted previously in our country, and they are also rare abroad. Method. Comprehensive experiments were carried out on beam specimens of the same cross-section, reinforced in three different ways — external sheet reinforcement (Type A), classical bar reinforcement designed for the same failure load (Type B), and bar reinforcement for twice the load (Type C). The experiment included short-term tests to failure and long-term tests with step-by-step loading; part of the beam specimens was loaded to 50% of the failure load before the long-term tests. During the testing, beam deflections and the nature of crack formation were investigated. Results. It was found that with the same load-bearing capacity and similar nature of deformation, significantly fewer cracks form in beams with external sheet reinforcement, but with a crack width an order of magnitude greater. Under long-term loading conditions, beams with external sheet reinforcement and initial cracks showed a smaller reduction in stiffness at the reloading stages compared to beams reinforced according to the classical scheme. The work confirmed the applicability of standard calculation methods for the first group of limit states to flexural elements with external sheet reinforcement. To increase crack resistance, the installation of additional structural bar reinforcement is recommended in them. The obtained data reveal the features of deformation of structures with external sheet reinforcement and determine the necessity for further research for other types of cross-sections and classes of concrete.
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Статья научная
The object of research is a concrete plate subjected to high-velocity projectile impact. The finite element method (FEM) is commonly used to obtain the nonlinear dynamic response of concrete structures. However, extreme loads such as projectile impact cause large strains, damages, material fragmentations. The mesh-based FEM cannot solve this task accurately. Smoothed particle hydrodynamics (SPH) is the meshless method that allows us to solve perforation and fragmentation problems but is characterized by higher computational costs. Methods. In this paper, we use the coupled FEM-SPH method to simulate the high-velocity concrete plate perforation. This method derives from switching from FEM to SPH by specific triggering criterion.Shear strain is the triggering criterion for the concrete plate perforation problem. The elastoplastic-damage Continuous Cap Surface Model (CSCM) describes nonlinear stress-strain relationships with strain-rate dependency for concrete. Results. Validation of CSCM on quasi-static cube compression gives good agreement with Eurocode-2 data: difference does not exceed 7% in FEM and 3.8% in the SPH method, respectively. For concrete plate perforation, the best match with the experiment is for the numerical model with spacings between FE nodes, and between SPH particles are equal to 2 mm. In this case, the ratio between the projectile diameter and the spatial discretization of approximately 6:1. The triggering value of shear strain for switching from FEM to SPH seems not to influence modeling results and computing time, independently of spatial discretization.
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Статья научная
Purpose of the present article is to introduce an unused analyze methodology for excavation of surge tank enlargement of HEC MATKA1. Paper exposes the explanation of the way which combines the analyzing methods of non-continual and continual media. The information about existing geological and geotechnical properties presents for the numerical and analytical analyses as a basis. Several results from the stability analyses of structural controlled instabilities during the excavation of water tank are also given. The newly secondary stress- deformation state as a result from enlargement (excavation) is analyzed with program Z-SOIL. The analyze of newly secondary stress-deformation state, which is the result from enlargement (excavation), was performed with Z-SOIL program.
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Static shading devices in the architecture of buildings
Статья научная
The paper shows that the daylight is a tool of energy efficiency of the buildings, if it is intelligently controlled. In order to reduce electricity consumptions and organize more natural illumination architects make bigger glazing area in their projects. However, shading devices are required to prevent overheating of inner premises. In the case classification of shading devices is given, as well as the European standarts in the field of shading devices. Also, the article includes guidelines for their designing, implementation and possibilities in using of building repairing. In the case study, the building of Agency for Electronic Communications and Postal Services in Podgorica, Montenegro is analyzed with the help of software tools, which present impact on distribution of daily illumination analysis, also designing of exterior static shading devices is considered.
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Strategies for redevelopment of gray belt objects on the basis of neural networks
Статья научная
The article considers the approaches for objects redevelopment in the gray belt. Information was collected about 45 objects located in different administrative districts of the city. As the criteria for clustering objects, general factors (year of construction of the building, сost of building restoration in prices of 1969, actual сost of building in prices of 1969, height, volume, number of stores, total building area, fundamental group, function) and factors on physical deterioration (wear of roof, floors, walls, foundation, finishing, MEP, total wear) were chosen. As a result of the study, SOMs with different learning parameters were created. As a result of the research, it was established how to change and select the desired redevelopment strategy for the zones of the gray belt, depending on the leaning parameters of the SOM and the individual characteristics of objects entering the gray belt.
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Strategy for energy efficient reconstruction of residential low-rise buildings o
Статья научная
Significant percent of population live in low-rise residential buildings. Energy efficiency of new houses is embodied in national regulations; proves on adequate energy performance represent the prerequisite for construction permit obtaining. Achieving energy efficiency in existing low-rise residential building, on the other hand, is more complex and problematic. By reviewing existing legal framework and taking into account the state on field, this paper aims to propose new methodology for energy performance improvement in existing low-rise residential sector (on the example of Montenegro and Serbia). Proposed problem solution is oriented towards both the additional legal actions and deeper understanding of social and economic impacts as barriers to energy efficiency achievement.
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Strength and deformability of compressed-bent masonry structures during and after fire
Статья научная
Monitoring of structures in conditions of beyond design basis impacts, including fire and similar impacts associated with exposure to elevated temperatures, which is relevant for both civil and industrial buildings, is especially important. The least studied area is the behavior of compressed-bent masonry structures in such conditions. Based on experimental data, a numerical analysis of compressed-bent masonry structures was carried out. Elevated temperatures from 500 to 1200 degrees were taken. Moreover, we took into account the change in the deformation-strength properties of the masonry depending on temperature, as well as the uneven heating of the structures and the stage of their cooling. The analysis results showed that at the stage of heating and maintaining a high temperature, the behavior of structure changes slightly, with the exception of temperatures of 1000-1200 degrees, when the material becomes ultra-brittle. It was also revealed that the most dangerous stage of cooling at the initial temperature rise above 800 degrees. This circumstance can be taken into account when developing monitoring systems for industrial facilities.
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Strength and durability of concrete using quarry dust as a substitute for sand
Статья научная
The object of research is quarry dust as a sustainable alternative to natural sand in M40-grade concrete, addressing the environmental and resource challenges caused by sand depletion in Russia. The study examines the effects of replacing fine aggregate with quarry dust (10% to 40%) on concrete's compressive strength, split tensile strength, and durability Method. The concrete mixes were designed following IS 10 262−2019 guidelines, with materials hand-mixed and each component precisely weighed. The mix was placed in cubic molds, compacted, and cured in water for 28 days. A total of 45 specimens were prepared and tested for compressive strength and split tensile strength at 7, 14, and 28 days using a universal testing machine C040PN, adhering to IS 516−1959 standards. Results. Replacing up to 20% of fine aggregate with quarry dust enhances compressive strength, achieving a peak strength of 46.35 MPa at 28 days, slightly below the control mix's 47.23 MPa. And up to 20% enhances tensile strength of concrete achieving a peak strength of 3.95 MPa at 28 days. However, beyond this threshold, performance declines, with strengths dropping to 35.21 MPa at 30% replacement and 34.04 MPa at 40%. making 20% the recommended limit for quarry dust substitution in M40-grade concrete. This approach enables sustainable use of quarry dust without sacrificing the structural qualities essential for construction.
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Structural inhomogeneity of metallic materials and quality criteria
Статья научная
The object of research is the structural inhomogeneity of metallic materials and its relationship with established quality criteria. The study focuses on the impact of microstructural variations, such as grain size distribution, defect presence, and phase heterogeneity, on the mechanical and physical properties of metals. Method. A combination of advanced microscopy techniques, statistical analysis of microstructural features, and standardized mechanical testing is employed to quantify structural inhomogeneity. Correlations between structural characteristics and quality indicators, such as strength, ductility, and durability, are established using regression models and quality standards. Results. The findings reveal that increased structural inhomogeneity negatively affects key quality parameters, including mechanical stability and material performance. Specific thresholds of inhomogeneity are identified, beyond which materials fail to meet quality standards. The study provides a framework for predicting material performance based on microstructural assessment and suggests pathways for improving quality through optimized processing techniques.
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Subsoil stabilized by polyurethane resin injection: fem calculation
Статья научная
The soil injection technology using an expandable polyurethane resin is one of the most efficient modern techniques that have been actively used in recent years for soil stabilization and foundations lifting. There are many advantages of using this technology, such as the rapid and strictly controlled process of lifting foundations, ease of use, high mobility and the lightweight of injectable foaming resin in addition to the independence of the physical and mechanical properties of resin from groundwater level, which allow the application of the proposed technology in a variety of geotechnical conditions and projects of various specificities. As part of the study of this technology in the world, very few theoretical and practical studies have been conducted. Most of these studies are focused mainly on the process of raising the foundations and monitoring of this technology. Thus, various monitoring methods have been developed around the world to control the injection process and to provide adequate tracking and a sufficient degree of visualization of the foundations lifting process in various geotechnical situations. Nevertheless, the application of this technology in the field of the soil stabilization and foundation strengthening has so far had certain limitations due to the lack of sufficient scientific theoretical and experimental justifications for the combined behavior of the composite (soil-resin) and the absence of an advanced calculation method, that allows predicting the altered characteristics of the treated soil massive after its injection by the expandable resin. The article demonstrates the results of a developed calculation method for predicting the averaged characteristics of the strengthened massive of a soil base after its injection by an expandable resin, based on theoretical and practical evidence obtained as a result of field and laboratory experiments, utilizing different approaches of the finite element method. The obtained by the developed calculation method results have been compared to the results of in-situ plate load tests obtained from field experiments without the injection of the resin and after its inclusion into the massive of the investigated soil to verify its accuracy.
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Substantiation of efficient use of land plots situated in the historical center of Saint Petersburg
Статья научная
The aim of the article is to find and substantiate an efficient use of unoccupied land plots in the central districts of Saint Petersburg. Three sectors of the city center were investigated and the most appropriate type of functional building assignment was chosen for the land. For this purpose in the research there was an analysis of the location of the chosen sectors, the experience of using the land of demolished buildings, the real estate market of the districts on which the land plots are located, also there was an interview of citizens for evaluating the potential exploitation of the sectors on certain criteria. According to the results, an art-development center got maximum rating but because of the economic reason – little space payback, building of the center is beside the purpose. The second place was given to a sports center but as one is currently situated not far from the investigated territories building of this structure is unprofitable. The third rating was for an overground parking which is very essential in the center of the city. As the social and economic significance of the parking are very high this object is the most favorable for building on the unoccupied territory. Efficient use of the land plot by choosing this object to be built in the central part of Saint Petersburg is confirmed by analyzed factors and results of the interview.
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Sulphur content in engine oil: Method for determining the amount
Статья научная
The object of the study is engine oil for internal combustion engines of agricultural machinery, with a focus on determining the content of sulphur and its compounds, such as sulphoxides and sulphides, which have a significant impact on the performance of oils. The research method involves the use of high precision titration techniques using specialised reagents and instruments to accurately measure sulphur concentrations. The obtained results demonstrate that the increased content of sulphur-containing compounds in motor oils leads to accelerated engine wear and increased negative impact on the environment. Application of the proposed methodology allows effective control of sulphur content, which contributes to optimisation of engine operation and reduction of machinery downtime. Thus, maintaining the optimal quality of engine oil is a key factor for increasing the service life of internal combustion engines and improving their efficiency in the agro-industrial complex.
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