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No 6 (2024)
Articles
Dependence of the Light Transmission Coefficients of Multifunctional Glazing on the Angle of Incidence of Radiation
Abstract
The operation of buildings with translucent facades increases the load on the heating and ventilation system due to transmission heat losses through the glazing, and on the air conditioning system due to possible overheating in summer. For this reason, glazing with sun protection, low-emissivity and multifunctional coatings is used in such facades. The characteristics of translucent enclosing structurers, as calculated according to normative documents, are taken into account when calculating the load on heating, ventilation and air conditioning systems, as well as when selecting the structures themselves in a given climate in order to save energy. In this case, the characteristics of the glazing were obtained in laboratory conditions when the radiation is perpendicular to the glazing, which is different from field conditions where the sun rays fall on the glazing at an angle. The available research works on the transmittance of solar radiation falling on glazing at an angle is based on laboratory studies, where various physical processes cannot be manifested and accounted for. Currently, research is being conducted in the Research Institute of Building Physics of the Russian Academy of Architecture and Construction Sciences to determine the empirical dependence of the light transmission coefficients of glazing with special coatings on the angle of incidence of the sun rays. The article presents part of the research and considers the determination of the light transmission coefficient of glazing with and without coatings from the angle of incidence of solar radiation.
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Calculations of the Acoustic Efficiency of Noise Shields Based on the Numerical Solution of the Sound Diffraction Equation
Abstract
Currently, noise-proof wall screens are widely used in urban development to protect against traffic noise, noise from ventilation equipment installed on the roofs of buildings, as well as from other linear and point noise sources. To assess the acoustic efficiency of such screens at the design stage, a practical calculation method proposed by Z. Maekawa for semi-infinite screens of simple geometric shape is used. At the same time, screens of other complex geometric shapes are widely used in the practice of noise reduction by screening in the absence and presence of various technological openings and holes in them. In this case, the application of the calculation method proposed by Z. Maekava may give significant errors in assessing the acoustic efficiency of shielding. For such cases, the article suggests using a method based on the numerical solution of the sound diffraction equation. A computer program has been developed for the numerical solution of the Fresnel-Kirghoff equation and, based on it, the possibility of solving practical problems is shown. Using the program, the influence of openings and gaps available in screens of finite sizes on the acoustic efficiency of shielding is estimated. The proposed numerical method can be applied at the design stage of complex shaped flat noise shields.
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Assessment of the Rationality of Design Solutions of Sound-Insulating Lightweight Partitions with Shotcreted Claddings
Abstract
In modern construction practice, partition structures are often used that do not meet regulatory requirements for airborne noise insulation. This reduces the acoustic comfort and safety of people in the rooms. An urgent task of building acoustics is to find structural solutions for enclosures with the required sound insulation properties and minimum values of surface density and thickness. New design solutions were considered: a lightweight frameless partition with acoustic isolation of the shotcreted claddings and the middle layer; lightweight frameless partition with acoustic separation of layers and fragmented shotcreted claddings. As analogues currently used in the design and construction of civil buildings, lightweight single-layer partitions made of tongue-and-groove gypsum slabs, gas silicate blocks, monolithic gypsum concrete, as well as multilayer lightweight frame-sheathing partitions are considered. A methodology has been developed for assessing the rationality of new design solutions for sound-insulating lightweight partitions in comparison with analogues. At the first stage of the assessment, enclosures that do not meet regulatory requirements for the value of the airborne noise insulation index are excluded. After this, a comparative analysis of the design solutions of the partitions is carried out according to two parameters: surface density and thickness. The results of the completed assessment are presented in tabular and graphical forms. An evaluation of a lightweight partition with shotcreted claddings in comparison with a frame-sheathing partition showed the rationality of the new type of enclosure in terms of surface density. The developed methodology for assessing rationality is recommended for use in the design of civil buildings. This will eliminate the use of lightweight partitions that do not meet regulatory requirements and select rational design solutions without inflated values of surface density and thickness.
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Anti-rating of Structural Floor Solutions for Shock Noise Insulation
Abstract
One of the important characteristics of a comfortable environment for a person’s daily stay is the sound insulation of enclosing structures. Insufficient indicators of sound insulation properties of enclosing structures have a negative impact on human health and work activity. To a large extent, both the physical and psychological state of the body is influenced by the level of shock noise. In order to assess these indicators, multiple tests of various floor structures were carried out to ensure that the index of the reduced shock noise level meets the current regulatory requirements. Various variants of structural solutions of overlaps between rooms in buildings of various purposes, which showed the worst values of the indices of the reduced shock noise level, are considered. The analysis of solutions and research presented in various reference and scientific materials and publications of previous years has been carried out. The dependence of the indices of the reduced level of shock noise of the ceilings on the applied design solutions and test conditions is analyzed. The composition of the floor construction layers is described in detail according to the information provided in the design and working documentation for each object of research. Graphs of the relative position of frequency characteristics and estimated spectra of the reduced level of shock noise under overlap for each considered structure are presented.
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Changes in the Characteristics of the Heating Period in Moscow Due to Global Climate Warming
Abstract
Currently, one of the main problems of the world community has become the problem of climate change on Earth, global warming has been recorded. On the territory of the Russian Federation, the average surface air temperature rises at a rate of 0.43оC per decade, which is more than two and a half times the rate of global warming and is recorded mainly in the winter and spring seasons. Important applied parameters of the cold season are the climatic characteristics of the heating period. Its duration and average temperature are the main indicators in estimates of energy costs for heating buildings. Reducing the average duration and increasing the temperature of the heating period create conditions for reducing the consumption of thermal energy. The reduction of energy costs during the heating period refers to the possible positive consequences for the Russian Federation of the expected climate changes, which have a significant potential for effective sectoral and regional economic development. For the rational use of climate change, it is necessary to take them into account in building codes. In the presented work, based on 60 years of observations by the Meteorological Observatory of the Faculty of Geography of Moscow State University, the variability of the main characteristics of the heating period in Moscow is analyzed. It is shown that there is a tendency to decrease the degree-day of the heating period, although there are years when the main characteristics of the heating period advise the climatic norm of earlier observations.
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Modeling of Bolts and Contact Interactions in a Finite Element Model of a Flange Connection
Abstract
Analysis of the strength of bolted joints is a common task in the design of buildings with a metal frame. As a rule, such calculations are performed by analytical methods. However, today there are many calculation programs that make it possible to analyze the strength of steel structures using the finite element method. The capabilities of such advanced CAE programs make it possible to create calculation models of flange connections with detailed elaboration. At the same time, the issue of justifying the use of computing resources and the correct balance between simplifying the model and the correctness of the results is becoming increasingly relevant. The relevance of this issue is due to the fact that detailed finite element models of the analyzed structures can reach a dimension of 105–106 elements, which, when performing dynamic or nonlinear static calculations, leads to the need for high computational resources. The article considers the need to take into account such factors as the tightening force of the bolt, the presence of the bolt body when modeling the flanged joint assembly of a steel frame (frame assembly) for subsequent static and dynamic analysis of the structure. Conclusions are drawn about the permissibility of various simplifications of the model, allowing to reduce the computing resources necessary for the calculation.
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Modelling the Structure of Highly Porous Materials
Abstract
Highly porous materials are the basis for four product groups: heat insulation, sound insulation and sound absorption, as well as insulation filling. In all cases, the parameter determining the properties of these materials is porosity, which also determines the conditions for energy transfer in the material. Pore size and shape, pore size distribution and porosity, thickness, structure, and nature of inter-ring membranes are also important characteristics (determining, first and foremost, their strength. These features of the structure and their influence on the properties of materials can be considered in the implementation of structural and mathematical models. The article describes the method and results of construction of complex structural model of high porous products on the example of particularly light and heat insulating mesh concrete. Analytical expressions for compressive strength, medium density and thermal conductivity are obtained. A nomogram has been constructed, with the help of which prognostic tasks of assessment of properties of mineral products of honeycomb structure can be solved depending on their porosity and nature of the structure-forming component.
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Green Certification of Residential Buildings in the Context of Sustainable Development
Abstract
It has become the guiding principle for long-term global development. Sustainable development involves the achievement of three fundamental goals: economic and social progress and environmental protection. The construction of healthy buildings involves, first of all, the creation of a favorable internal environment for future inhabitants, but also includes issues of environmental protection and the labor of builders. Green certification of residential buildings in Russia not only promotes more sustainable use of resources and reduces environmental impact, but also creates favorable conditions for the health and comfort of residents. Within the framework of this publication, the authors analyzed the advantages of using green certification of buildings, examined in detail the economic benefits of green certification, analyzed the process of certification of buildings, analyzed the advantages of green certificates using the example of commissioned buildings, considered the difficulties of introducing green certification, and identified prospects for the development of green certification in construction residential buildings.
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On the Size of the Step Along the Azimuth of the Wind Flow During Aerodynamic Studies of High-Rise Buildings
Abstract
In recent decades, high-rise construction has been actively developing in the Russian Federation. This led to a significant increase in aerodynamic studies of high-altitude objects in accordance with the methodology of SP 20.13330.2016 «SNiP 2.01.07-85* Loads and Impacts». In many domestic and foreign works, when conducting such studies, the step in the azimuth angle of the wind flow is 15 degrees (less often 20 degrees). This paper presents results that show that such a wind azimuth step, in conditions of dense multi-height buildings, results in a significant underestimation of local negative peak wind loads. The question of sufficiency of the wind flow azimuth step of 5 degrees is discussed.
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A Probabilistic Approach to Design of Steel Trusses with Incomplete Statistical Data
Abstract
One of the promising directions of development of structural design standards is the transition to full probabilistic methods of structural design for a given target reliability level. For estimation of the reliability index, effective accounting and modeling of aleatory and epistemic uncertainties of data is necessary. The article describes a probabilistic approach to the design of steel truss elements taking into account incomplete statistical data. This approach allows giving an estimate of the failure probability for a steel truss under uncertainty data. The failure probability presented in the form of an interval that will narrow as additional statistical data about loads, material properties, geometric imperfections, etc. grows. To solve this problem, the article uses two numerical approaches to calculate the failure probability: discretization of p-boxes into Dempster-Shafer structures and the interval Monte Carlo (IMC) method. The use of the presented approach in practice also allows performing a comparative evaluation of different technical and economic solutions of steel trusses based on the reliability factor.
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