English English

Archives

THE RELIABILITY COEFFICIENT FOR FIBRE CONCRETE MATERIAL

https://doi.org/10.58224/2618-7183-2022-5-2-51-58
, , , , ,
 51-58 p.
Abstract
One of the main parameters of the method for calculating building structures made of concrete and fibre concrete by limiting states is the reliability coefficient for the material, which characterizes the heterogeneity of the physical and mechanical properties of the material. In national and foreign standards, it takes a constant value of 1.3 (obtained on the basis of direct tests), or 1.5 (obtained on the basis of indirect tests and the use of graduated dependencies). The concrete matrix for the formation of the structure of fibre concrete is most often fine-grained concrete with special additives, which has greater uniformity in comparison with heavy concrete, which cannot but affect the reliability of the composite material in question as a whole: the stock coefficients for fibre concrete should be lower than for normal concrete, which has not been reflected in modern standards for design yet. Starting from interval estimates of the average strength value, a new approach to determining the reliability coefficient for the material, differentiated by the 1st and 2nd groups of limit states, is proposed. The results of calculations according to the proposed formulas for previously conducted tests of steel- and glass-fiber concrete images allowed us to conclude: the introduction of fiber into the concrete matrix of the proposed effective composite composition increases the uniformity of the strength properties of the material, which leads to an increase in the reliability of its use in building structures, a decrease in the value of the reliability coefficient (margin) for the material to 1.164...1.235 for central axial compression and up to 1.172...1.272 – for central axial stretching. The obtained actual coefficients in strength calculations will allow to reveal the supplemented reserves of the bearing capacity of structures made of this material up to 22.4%.
PDF

THE PRACTICE OF USING TECHNICAL FABRICS IN THE PRODUCTION OF HEAT-RESISTANT SLEEVES

https://doi.org/10.34031/2618-7183-2022-5-1-5-14
, , , ,
 5-14 p.
Abstract
The article has developed and mastered promising technologies for the production of heat-resistant metallurgical hoses, which include the use of synthetic materials for the power frame and fire-resistant - cover fibrous materials. Experimental studies have been carried out to reduce the material consumption of the production of sleeves, due to changes in manufacturing technology at the stage of cutting the strips of the power frame and assembling the sleeves. A sleeve manufacturing technology is described, which provides for the introduction of a wire spiral into the sleeve design to protect the sleeves from loss of transverse stability and reduce the bending radius. Technical cord materials for the manufacture of a power frame for sleeves of various types in production are considered. The technology of protecting the outer surface has been mastered, providing for the creation of bumpers of various design schemes. In order to increase the temperature resistance of the operation of metallurgical heat-resistant sleeves, a technology has been created for the manufacture of sleeves based on non-flammable and fire-resistant fabric materials covering the sleeves on the outer surface. The operation of the hoses showed the correctness of the developed technologies and the choice of appropriate materials. Research work on the development of new fire-resistant materials for heat-resistant hoses has been carried out. The prospects of using innovative technology for manufacturing heat-resistant metallurgical hoses are noted.
PDF

FUNCTIONAL AND STRUCTURAL CONNECTIONS IN THE ARCHITECTURE OF MODERN INDUSTRIAL BUILDINGS

https://doi.org/10.34031/2618-7183-2022-5-1-15-37
 15-37 p.
Abstract
Today, up to 80% of buildings and structures are built on deep foundations, the main elements of which are concrete and reinforced concrete piles (hammered, bored and piles made according to CFA technology). Since the beginning of the mass use of drilling piles (the 60s of the last century), there is still a problem of ensuring the reliability of foundations, due to the fact that the process of installing piles is hidden from observation, and unacceptable defects may form in the pile trunks, which reduce the bearing capacity of piles and can lead the structure to an emergency condition. Pile construction technologies are constantly being improved, however, it is still not possible to avoid the appearance of defects in pile trunks because there are quite a lot of reasons for the formation of defects that it is not always possible to foresee and take into account. That is why, during the construction of deep foundations, output monitoring of the technical condition of drill pile shafts should be provided, which cannot be performed without the use of non-destructive diagnostic methods. The use of these methods and means, which implements them, should be mandatory to ensure the reliability and safety of the operation of buildings and structures and today is already provided for by numerous standards and regulatory documents. Currently, acoustic methods are mainly used for diagnostics, namely: single- and multi-channel acoustic logging; pulse Echo method with shock excitation of elastic waves (hereinafter referred to as the method of vibration-shock diagnostics). It should be noted that in the case of using high deformation to excite elastic waves, at which the impact energy on the end of the pile reaches the limit of proportionality, an assessment of the bearing capacity of experimental piles is given, and the low technique is used exclusively for diagnosing pile trunks. For a long time, these methods could not be widely implemented in the field. Their capabilities have increased significantly after the development of digital signal processing methods.
PDF

MODULAR STRUCTURES AS A METHOD OF ARCHITECTURAL ENVIRONMENT ARRANGEMENT

https://doi.org/10.34031/2618-7183-2022-5-1-38-53
 38-53 p.
Abstract
Key versions of the concept «module» in the sphere of architectural design are considered. Modular structures are defined as a means of creating a flexible and dynamic architectural environment with variable functional parameters, the main potential of which is expressed in the speed of erection, autonomy, economical efficiency, transformative possibilities. The main features and advantages of the modular structures as well as the most effective fields of their application are considered. Examples are given of modular objects from current construction practices that illustrate the possibilities and specific means of their formation. Special emphasis has been placed on the ecological feasibility of modular facilities, as well as on the possibility of their interaction with the established architectural context. The use of the modular method in extreme conditions, including the formation of a habitable environment in outer space, is considered.
PDF

FEATURES OF DEVELOPING UNIQUE ARCHITECTURAL SOLUTIONS USING DIGITAL METHODS BASED ON VISUAL PROGRAMMING

https://doi.org/10.34031/2618-7183-2022-5-1-54-59
 54-59 p.
Abstract
The article deals with the creation of a parametric facade by writing an algorithm based on attractor modeling methods. The article analyzes various options for extracting facade solutions based on world and domestic design experience. In addition, the article describes in detail the general algorithm for creating a parametric facade using the Rhinoceros program and the Grasshopper component environment. Architecture combined with modern digital technologies can provide an opportunity for the emergence of a new type of architectural thinking both in the context of shaping and in the context of design. Today, the architectural world is constantly replenished with new innovative tools and the design methods generated by them, but until now there was no clear classification and structuring of emerging opportunities. At the early stages of the emergence of digital methods, it is important to create a hierarchy of all tools and understand which one is suitable for certain tasks, create a base of experiments and results based on the latest methods. This approach finds its relevance in modern methods of architectural design, as it provides an alternative choice of options and a high speed of automated modeling.
PDF

STABILIZATION OF SUBSIDENCE OF BUILDINGS OF MODERN MEDICAL CENTERS

https://doi.org/10.34031/2618-7183-2021-4-6-5-25
 5-25 p.
Abstract
The group of deformed structures includes buildings that have received unacceptable subsidence and deformation during the period of their construction and especially operation, which, however, do not interfere with the performance of their main functions, but may eventually collapse. Their causes are errors in engineering and geological surveys and design; violation of the rules for performing construction work and operation of buildings and structures. Long-term geodetic observations of the precipitation of the foundations of buildings on pile foundations have shown that both absolute and relative stabilized values of subsidence in the vast majority of cases are less than them and the normative limit values are calculated. Therefore, the group of deformed buildings on pile foundations includes somewhat less often similar objects with shallow foundations. The reasons for excessive subsidence of the foundations of pile foundations of buildings (and as a result, the occurrence and development of cracks and other deformations in load – bearing structures), in addition to these, are most often: unjustified use of increasing correction coefficients for the results of compression tests of highly acidic soils; the lower ends of the piles falling into layers of weak soil; the tip of the piles sinking from the design mark; overestimation of the bearing capacity of the piles due to non-compliance with the optimal time of their "rest" after immersion or erroneous interpretation of the graphs "load-pile sediment"; excessively close placement of neighboring piles in the plan, which when they are immersed, especially in the sand, leads to "pushing" up previously submerged; uneven loading of piles as part of the grillage; deformation of existing buildings and structures when driving piles near and tongue-and-groove, the development of pits, etc.
PDF

THE USE OF NANOTECHNOLOGY FOR THE DESIGN OF BUILDING STRUCTURES

https://doi.org/10.34031/2618-7183-2021-4-6-26-47
 26-47 p.
Abstract
Russia has a developed industry of building materials, which today implements an energy- and resource-saving model of its development. The implementation of the state policy of resource conservation is carried out in two main directions: the first direction is to save resources in the production of materials, the second is to increase the production of energy–efficient materials that allow saving energy carriers during their operation. Modern construction in Russia is guided by European construction standards, which, in turn, provides for the construction of energy-saving buildings with minimal energy consumption from external sources. This is ensured by the use of structural and thermal insulation materials in the construction of external walls. In modern structural and thermal insulation materials for energy-saving construction, high requirements are imposed on their thermal properties, mechanical strength and comfort level. From the point of view of simultaneous satisfaction of these requirements, ceramic materials have obvious advantages over other materials, in particular cellular concretes, which, with almost the same level of thermal conductivity, are characterized by the least hygroscopicity and significantly greater strength. An objective prospect for the development of structural and thermal insulation ceramics is the production of hollow ceramic stones with increased thermal efficiency for their use in economical single-layer external wall structures without additional insulation. The products of individual Ukrainian manufacturers and even imported analogues of the most famous European manufacturer (Wiernerberger Company, Austria), when used in single-layer walls, do not provide regulatory requirements for the heat transfer resistance of masonry for the first temperature zone of Russia, which occupies the majority of the territory (60%). This requires the improvement of domestic products in the direction of improving their thermal characteristics (reducing thermal conductivity and increasing thermal resistance).
PDF

EXAMINATION OF THE QUALITY OF NANOMATERIALS IN THE DEVELOPMENT AND APPLICATION OF CIRCULATING RESOURCES IN CONSTRUCTION

https://doi.org/10.34031/2618-7183-2021-4-6-48-68
,
 48-68 p.
Abstract
The advantage of the equality indicator is the relative simplicity of definition and the possibility of periodic monitoring. According to the equality indicator, it is possible to assign repairs and predict the service life, assess the condition of the road surface. Experimental studies have proved that there is a connection be-tween the evenness of the coating and the strength of the pavement, which opens up the possibility of determining the structural strength of non-rigid pavement, which provides a given evenness of the coating for the last year of operation before major repairs. The question of assessing the impact of the unevenness of the road surface on the processes of development and accumulation of deformations, changes in the evenness of the coating during operation remain largely open. This is due to the multifactorial nature of the problem of predicting the equality of coverage, so it is advisable to use approaches based on direct measurement methods. Most of the existing models of interaction of a pneumatic or rigid wheel with a coating are designed for problems of pavement mechanics or car theory, therefore they cannot be unambiguously applied to determine the value of the dynamism coefficient. A significant disadvantage of these solutions is insufficient consideration of the deformative properties (modulus of elasticity) of the pavement.
PDF

THE INFLUENCE OF FORCED CARBONIZATION ON THE PROPERTIES OF GYPSUM-LIME SYSTEMS BASED ON SECONDARY RAW MATERIALS

https://doi.org/10.34031/2618-7183-2021-4-6-69-81
, , , ,
 69-81 p.
Abstract
The use of secondary raw materials for the production of building materials is a modern trend in solving environmental problems. In the Republic of Crimea, dumps of secondary raw materials – phosphogypsum and lime dust – have accumulated in large quantities at various enterprises. The analysis of phosphogypsum, which has been in the dumps for more than 5 years, showed that by its quality indicators it can be attributed to the 2nd grade in accordance with GOST 4013-2019, and the specific effective activity of the material (Aeff) corresponds to the I class of materials, which makes it suitable for the production of gypsum binders. Prototypes-cylinders were made from a mixture of phosphogypsum with lime dust of 1:1 composition at a pressure of 30 MPa and then subjected to hardening according to three schemes, in order to separate the passage of various types of hardening and study each of them for the physico-mechanical properties of the resulting material. The analysis of experimental data made it possible to establish the effectiveness of simultaneous flow in the system of two types of hardening – carbonate and hydration for lime and phosphogypsum components of the raw mixture, respectively. As a result of the organization of a mixed type of hardening of gypsum-lime binder, samples with a compressive strength of 26.5 MPa and a softening coefficient of 0.63 were obtained within 90 minutes. The calcium carbonate formed in the process, which is the product of the reaction between calcium hydroxide and carbon dioxide, significantly increases the water resistance of the hydration products of gypsum binder. It is established that with an optimal combination of technological factors and hardening conditions, a significant increase in the physical and mechanical characteristics of the carbonized material is possible in a short time.
PDF

STRUCTURE FORMATION OF C-S-H FROM THE POSITION OF MICROMECHANICS OF COMPOSITE MEDIA

https://doi.org/10.34031/2618-7183-2021-4-5-5-15
,
 5-15 p.
Abstract
The creation of an environmentally friendly building material to protect the human environment can only be carried out from the position of a transdisciplinarity approach, taking into account modern achievements in geomimetics and micromechanics of composite media. A wide range of basalt-fiber-reinforced concrete based on composite binders has been developed, which have increased characteristics of impermeability and durability under extreme operating conditions. The nature of the influence of the composition and manufacturing technology of cement composites on the pore structure of the composite has been established, which has a positive effect on the characteristics of gas, water and vapor permeability. High early strength was obtained, which allows the use of materials for operational repair and construction in emergency situations. The positive influence of the composition of the developed composite on the performances has been proved. The water resistance of the modified composite provides a water pressure of 2 MPa for 148 hours, which corresponds to the W18 grade (for the control sample – W8), the frost resistance grade – F300. It was found that the water absorption of the modified concrete samples was lower than that of the control sample, which is explained by the decrease in the pore structure index λ by 28.4 times, and the average pore diameter by 3.05 times. The total pore volume of the modified concrete was lower and decreased with increasing dose of nanosilica.
PDF