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No 6 (2024)
- Year: 2024
- Articles: 14
- URL: https://rjdentistry.com/0585-430X/issue/view/9294
International Scientific Conference – XV Academic readings dedicated to the memory of Academician of RAACS Osipov G.L., "Actual problems of building physics. Energy saving. Reliability of building structures and environmental safety. Artificial Intelligence"
Dissipative theory in the residential buildings pipe-concrete structures study
Abstract
The pipe-concrete structures stress-strain state and load-bearing capacity abstract theorem are discussed in this article and experimental studies are carried out to confirm them. Pipe concrete structures prototypes were made of high-strength concrete with spiral reinforcement and high-strength longitudinal reinforcement. The developed compressed pipe-concrete structures have increased strength and have high ultimate axial deformations. Significantly greater energy is required compared to traditionally used load-bearing elements to destroy such a structure. This circumstance makes them especially attractive for use in buildings and structures erected in seismically active zones, as well as for unique buildings and structures. The compressed pipe-concrete element design was improved based on the research results. It was possible to significantly increase its strength compared to known analogues due to the high-strength tensile concrete use. Such elements maximum deformation exceeds 1%, which opens up good opportunities for use. The developed structure high strength and ductility indicate that their destruction requires a large energy. It will significantly increase the frames survivability made of using pipe-concrete elements.
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Theoretical Prospects for the Modification of a Cement Mixture by the Introduction of Mineral Wool for its Secondary Use
Abstract
Currently, the issue of reuse of various materials that have served their useful life, as well as waste from the production of these materials, has become relevant in all areas of industry. The use of modern technologies already makes it possible to efficiently process various wastes, but in most cases the use of raw materials obtained in this way poses a serious task for engineers and technologists. One of the most common products of the construction industry is a different kind of insulation, as an integral part of the structure, which provides effective energy protection of buildings from heat loss during cold periods of the year. Mineral wool, as an effective method of protection, is actively used now and was popular in the 20th century. Many buildings, when decommissioned, respectively, contain insulation in the mass of waste, creating the task of developing methods for using it repeatedly or after recycling.
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Researching and Evaluation of Thermal Properties of Foamed Glass Crushed Stone in Conditions of Problem Soils
Abstract
The purpose of the work was to study the heat-protective qualities of foam glass crushed stone based on diatomite and cullet and to assess its applicability as part of the roadway in permafrost areas. Experimental definitions of thermal engineering parameters of foam glass crushed stone made of cullet and diatomite, including bulk density, operational density, compressive strength in a cylinder at a given operational density, thermal conductivity, have been carried out. The thermophysical characteristics of backfilling from foam glass crushed stone based on cullet at a 30% degree of compaction have been studied. The values of thermal conductivity of foam glass crushed stone in dry, frozen, and thawed conditions are determined. The experimental data obtained were the basis for computer modeling and calculation of soil temperature fields with a pavement structure in the territory of permafrost distribution (Republic of Sakha, Yakutia). The calculation of the temperature regime change with a forecast for 12 months was carried out. For comparison, the calculation of a similar road structure without a thermal insulation layer, using coarse sand, is presented. The calculation results show the effectiveness of using foam glass rubble filling in the construction of the pavement; it was found that the thermal insulation layer of foam glass rubble prevents the defrosting of a layer of permafrost soils.
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The Transfer Theory Application in the Thermal Insulation Materials Durability Research
Abstract
To ensure a sufficient level of thermal protection of buildings in accordance with Federal Law 261-FZ, mass heat insulation of newly erected and existing buildings began after 2009. The issues of changing the performance indicators of thermal insulation materials over time from the standpoint of energy efficiency of buildings are of great interest. The paper considers the issues of durability of insulation used in different regions of Russia. It is proposed to use an equation based on the theory of transfer for a comparative analysis of the performance indicators of thermal insulation materials. The proposed equation makes it possible to analyze data obtained by different authors using various research methods (laboratory experiments, field tests, forecasting properties using computer modeling). Using the transfer theory, changes in the coefficient of thermal conductivity and strength of heat insulation materials are investigated based on the results of studies of materials in a climate chamber and computer modeling. It has been established that the initial rates of change processes in strength and thermal conductivity coefficient have the same orientation for the data obtained by different authors, however, in absolute values the results differ significantly from each other, perhaps this is due to the inaccuracy of the initial data. In further work, it is proposed to conduct full-scale thermal imaging studies of materials, which will make it possible to adjust the values of the initial velocity and braking coefficient for different materials, taking into account climatic conditions. The calculated values of the initial velocity and the braking coefficient of the process will make it possible to predict with high accuracy the change in the operational parameters of the material over time.
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Improvement of Shock Noise Insulation by Elastic Gaskets in Floating Floor Structures
Abstract
A comfortable acoustic environment in residential and public buildings is an important task that can be solved only in a complex of special constructive measures, one of which is to improve the sound insulation of enclosing structures, including floor-to-floor ceilings. The article presents the results of laboratory tests of building materials used as elastic gaskets when installing floating floors. The compositions of floating floors are described, graphs of the frequency dependence of the improvement of shock noise insulation by tested structures, as well as their single-digit characteristics are given.
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New Set of Rules 415.1325800.2023 on Acoustic Design of Sports and Entertainment Facilities
Abstract
Code of Rules 415.1325800.2018 “Public buildings. The Rules of Acoustic design”, which was released in 2018, contains methods of acoustic design of indoor sports and entertainment facilities with a capacity of up to 25 thousand people, the air volume of which is limited to 50 thousand m3. However, over the past 10 years, massive construction of large sports arenas with a capacity of more than 50 thousand people and an air volume of more than 500 thousand m3 has begun in Russia. In addition, all modern sports facilities are designed and built as multifunctional playgrounds, where, in addition to sports competitions, concert and entertainment events can also be held. Thus, the approaches and methods of acoustic design outlined in the 2018 Set of Rules currently do not meet the features of modern sports arenas with large capacity and large air volume, in which it is important to ensure a high level of acoustic comfort. The article presents a new Set of rules 415.1325800.2023 “Public buildings. Rules of acoustic design”, which proposes modern approaches to determining the optimal reverberation time depending on the air volume of the room. An additional parameter for the normalization of acoustic comfort is considered – the FSI fan support index. The data on the sound-absorbing characteristics of modern materials used in the decoration of arenas are updated. Simple analytical algorithms for estimating reverberation time in open, semi-open and closed arenas are proposed.
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The Influence of Air Permeability of Building Envelope Materials on the Energy Consumption of Heating Systems
Abstract
Thermal insulation materials used in external enclosing structures, depending on their basic properties, design solutions implemented with their help, the quality of their manufacture and installation, and taking into account the peculiarities of the operating mode, can perform their functions with varying efficiency. This can significantly affect the heat consumption of building heating systems. The paper presents the result of an ongoing experiment to assess the energy consumption of buildings depending on the type of structure and characteristics of their external fences. The test results confirmed the existence of a connection between the intense wind impact on the facade of the building, the air permeability of the enclosing structure and its individual constituent layers and the parameters of the air heating system.
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Study of Factors Influencing Sound Insulation Existing Fences with Additional Sound Insulation at the Site Using Layered Vibration-Damped Elements
Abstract
The results of experimental studies of the sound insulating qualities of fences with flexible slabs on the side, made in reverberation rooms, are presented, and an analysis of the influence of some parameters on their sound insulation is given. It has been shown that the installation of flexible slabs is most rational when the airborne noise insulation index of the main structure is in the range of 40–45 dB. At higher indices, the effectiveness of additional sound insulation decreases.
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Application of the Moisture Potential Theory in Assessing the Heat and Moisture Regime of Building Envelopes
Abstract
The review of existing mathematical models for humidity conditions was carried out. Methods giving an opportunity to calculate moisture transfer in the sorption zone of humidification and in the supersorption zone are described. The features of calculating moisture distribution using the theory of moisture potential are shown. The new discrete-continuous method for calculating the moisture state of a fence is proposed, which makes it possible to determine the unsteady-state moisture regime using an analytical expression without using various numerical methods. Two formulas for a single-layer and a multi-layer building envelope are derived. The formula allows us to determine the distribution of moisture potential in various sections of building envelopes. The effectiveness of the method is proven by comparing the results obtained with calculations using non-stationary and engineering quasi-stationary calculation methods. The humidity regime of a single-layer enclosing structure in the city of Moscow made of aerated concrete blocks, as well as a two-layer enclosing structure with a clay brick base and silicate brick cladding was calculated. It is shown that the calculation results using the proposed method are both quantitatively and qualitatively close to the distribution obtained using the non-stationary calculation method for both single-layer and multi-layer enclosing structures. The method is recommended for use in engineering work, because it gives a possibility to take into account the inertia of moisture in the building envelope.
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Polymers in construction
Theoretical Principles Used to Study the Formation of Polyepoxyurethaneisocyanurates. Part 2
Abstract
The quantitative description of the effect of the resulting chemical structures of polyepoxyurethaneisocyanurates on the glass transition temperature Tg was carried out. This is done by selecting copolymer structures whose Tg value is comparable to the calculated one, and the error does not exceed 1.8–2%. The theoretical data were obtained on the basis of calculations of model structures using the “Cascade” computer program (INEOS RAS).
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Scientific and practical conference "Stroypolymers-24" in Kazan
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Concretes: science and practice
An Outstanding Engineer, Scientist, Teacher — Alexander Matveevich Ivanov. To the 110th Anniversary of His Birth
Abstract
The scientific works of an outstanding scientist, A.M. Ivanov, devoted to the development of new methods for calculating wooden elements taking into account the time – creep factor have so far aroused great interest among modern researchers. The Voronezh Scientific School of Polymer Concrete A.M. Ivanov has substantiated and created universal models called “structural diagrams”, which lay the probabilistic foundations for evaluating the properties of materials, as well as polymer concrete and other composites. The article describes the life path, the formation of scientific activity and teaching of an outstanding scientist, Dr. of Technical Sciences, Professor A.M. Ivanov, a participant in the Great Patriotic War. Grateful students and followers showed that the issues of reinforcement of steel-polymer concrete structures, anchoring of reinforcement in polymer concrete and calculation of joints of prefabricated steel-polymer concrete structures of solid and annular cross-section with various types of reinforcement; the development of a whole range of polymer materials reinforced with fiberglass reinforcement and wood chips is the result of mentoring activities of an outstanding teacher and scientist.
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Setting Deadlines for the Manufacture of Monolithic Concrete Structures During Construction and Technical Examinations
Abstract
The use of special knowledge in the field of building materials science is increasingly in demand in modern legal proceedings when conducting judicial construction and technical examinations in order to obtain an evidence base, in particular, on determining the timing of construction work. It is known that when conducting expert studies, it is possible to assess the increase in concrete strength due to the continued hydration of cement and a decrease in the basicity (pH) of the surface layer of concrete due to the processes of carbonization of cement stone in interaction with the atmosphere. The paper presents proven mathematical dependencies that make it possible to link the temporary change in the strength of concrete and the carbonation of the surface layer of concrete laid in monolithic structures with the structural parameters of concrete and its durability. These dependencies give the construction expert a fundamental opportunity to determine the age of concrete by changing the specified characteristics of concrete and, consequently, to determine the time period in which the construction structure was created from this concrete. Thus, expert determination of the production time of monolithic concrete structures is possible and is based on conducting research to establish the actual strength of concrete and determine the depth of its surface carbonation at the time of expert research. The described methodology for determining the timing of construction work on the manufacture of monolithic concrete structures in building conditions was used when conducting forensic examination.
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Results of scientific research
On the Issue of Fatigue Classification of Cement Composites
Abstract
The abstract generalization of the specifics of fatigue degradation of cement composites due to structural and physical heterogeneity, ambiguity of energy and mechanical effects of induced changes, interdependence of impacts and response, etc., is presented, which together do not make it possible to use the methodology and principles of the limit state method for its assessment. A phenomenological approach to the design accounting of fatigue is proposed by introducing a normative classification of the resistance of composites to non-stationary influences. In the experimental part of the work, prismatic samples of two series were tested: concrete and fiber concrete with polypropylene fibers. All tests were carried out in automatic mode according to a specially developed program at the Instron 5989 test complex, in compliance with the constancy of the deformation rate of the samples of 0.04 mm/s. External influences are modeled by 50 load-unloading cycles with an amplitude of η=0.8 and zero asymmetry (ρ=0). Cyclic loading was completed by monotonous compression until complete destruction of the samples. The acceptability of the laws of the kinetic concept of strength and its criterion (failure time) for assessing fatigue durability is experimentally and analytically substantiated. The practical identity of the kinetics of resistance time and significant indicators of operational suitability is confirmed.
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