Load-bearing Structures Research Articles

Research on the Combustion Characteristics of Coal Piles and the Fire Risks of Closed Coal Bunkers

Closed coal bunkers emerged as a novel form of coal storage for coal-fired power stations. Nevertheless, heat builds continually in the storage process because of the constant oxidation of coal and combined with the impact of a confined coal bunker environment, it is difficult for heat to dissipate, resulting in frequent coal bunker fires. Consequently, research on coal pile combustion characteristics is crucial to the design of coal bunker safety. The experimental platform was set up in this study to conduct combustion tests of various specifications, and the burning rate, flame height, flame temperature, and heat radiation flux were analyzed to identify the critical parameters impacting coal bunker safety. First, the maximum burning rate of coal heaps during steady burning was calculated, improving coal pile combustion theory and providing guidance for coal bunker design. Second, the maximum flame height was determined, which can provide an important design guide for coal bunker height designs. In addition, it was discovered that high temperatures in flames, smoke, and smoldering coal might cause coal bunker buildings to collapse, so future designs should strengthen coal bunker fire resistance and keep the coal pile away from the load-bearing structures to prevent collapse from excessive temperatures. Moreover, the diameter of coal piles has an influence on the heat flow. For this reason, a coal bunker’s design must consider the coal pile’s fire separation distance from the coal bunker and avoid large coal piles. Consequently, the study gives recommendations and support for planning coal bunker safety and enriches experimental data for coal pile fires.

Thermal vibration analysis of functionally graded graphene platelets-reinforced porous beams using the transfer function method

Functionally graded graphene platelets-reinforced (FG-GPL) porous materials are advanced, designable, lightweight, and high-strength composite materials promising in launch vehicles, space shuttles, and hypersonic vehicles as integrated heat-protection and load-bearing structures. Thermal vibration analysis ensures service safety in environments with dynamic thermal loads. A free vibration analysis model of an FG-GPL porous beam was proposed based on the micromechanical model and Timoshenko beam theory (TBT) under a nonlinear temperature profile. First, three types of functionally graded porosity distributions and graphene-platelet dispersion patterns were assumed along the thickness direction of the beam. Material properties, including elastic modulus, Poisson’s ratio, and density, were calculated using the Gaussian random field scheme and Halpin–Tsai model. Second, a nonlinear temperature profile was established considering the influence of porosity and graphene platelets by solving a one-dimensional–heat-conduction equation. Third, the governing equations of thermal vibration of the beam were obtained using the TBT and Hamilton’s principle. The frequencies of different porosity distributions and graphene-platelet dispersion pattern combinations were calculated by solving the governing equations using the transfer function method. Finally, the results were validated, and the parameter effects of the temperature profiles, weight fraction of graphene platelets, porosity coefficient, and thermal gradient on the fundamental frequencies were analyzed. Compared to a linear temperature profile, the frequency under a nonlinear temperature profile is hardly changed for the combined symmetrically distributed porosity and GPL beams, while it is different for the asymmetric combinations.

Parametric Numerical Study of Welded Aluminium Beam-to-Column Joints

Beam-to-column joints are one of the most common types of joints in metal structures. In the design of load-bearing aluminium structures, welding, as a joining method, is often avoided because of localised degradation of mechanical properties in the heat-affected zone (HAZ). However, recent experimental studies on the extent and strength of the HAZ show a significant difference compared to very conservative design rules when modern welding techniques are used. Therefore, the numerical study conducted in this paper addresses the influence of HAZ on the mechanical behaviour of the welded aluminium beam-to-column joint. Parametric numerical analyses were performed varying the aluminium alloys, the reduced mechanical properties of the HAZ, and different definitions of the HAZ extent. The obtained results show that the highest stress concentration occurs at the connection between the top beam flange and the column flange, resulting in plastic softening in this region. Different joint capacities were observed by varying the mechanical properties of the HAZ. A detailed overview of numerical models as well as the obtained moment–rotation curves show that the behaviour of some models is not as conservative as assumed in the design standards considered.

Structural design and axial compression test of novel carbon-fiber-reinforced polymer truss supporting rear connection-ring

Based on the “light-weight, heavy-load, and large-span” composite truss design goal for the load-bearing structures of large aircraft, the joint construction pattern, modular integration approach, unique connection method for rear connection-rings, and structural design of composite trusses are studied in detail; a novel carbon-fiber-reinforced polymer (CFRP) truss supporting rear connection-ring is proposed. Based on the force characteristics of different section positions and the advantages of different joint types, three different joint types have been adopted: plate-shell-integrated joint (only single-K and double-K patterns), aluminum alloy joints, and butt joints. This can help fully analyze the advantages of different joint types and achieve the optimal design of composite trusses. Each truss module can be designed separately based on the specific functional and usability requirements, which increases the design freedom of the composite truss, and gives the composite truss an aesthetic three-dimensional structure. Based on the unique construction characteristics of the truss ends, axial compression performance tests were carried out on the designed and fabricated 1:1 CFRP truss prototype, with a span of 18.5 m, using specific axial loading equipment. The research results show that the unique connection method of the rear connection-ring achieved uniform load transfer from the rear connection-ring to the truss; the CFRP truss prototype meets two design requirements (bearing capacity ≥55.0 kN, axial compression deformation <1/1500), and is particularly suitable for the rear connection-ring to transmit large loads effectively. The proposed novel CFRP truss supporting rear connection-ring has the advantages of efficient structure assemblage, high design freedom, and flexible construction, which meets the design requirements in terms of truss functionality and realizes the “large-span, heavy-load, and light-weight” structural design goal.

Experimental study on the mechanical performance of tyre encased soil elements for structural wall applications

Tyre-encased-soil elements (TESEs) are segmental units made by compacting soil inside the cavity of EOL tyres. The TESEs can function similarly to bricks to build masonry walls or other load-bearing structures. Tyre walls built of TESEs have proven successful architectural and structural performance. However, the mechanical properties of TESEs have not been scientifically investigated in the past, and insufficient evidence restricted TESEs’ further application as structural components. This project attempted to fill the gap by studying the performance of TESEs subject to axial compressive loads through both laboratory experiments and analytical analysis. Soils with different properties were used in the experiments to quantify their influence on the TESEs performance. It was found that within the range of loading applied in this study, no abrupt failure was observed on the tested TESEs. The axial stress-strain relationship followed an exponential form, possibly due to the strain-hardening effect brought in by the densification of encased soil and increased confinement support from the tyre reinforcement. The encased soil’s density had a significant influence on the load-deformation behaviour of the TESEs. However, the load-carrying capacities were not highly sensitive to the soil type and its moisture content. An analytical model was proposed for capturing the axial and radial strain of TESEs under applied axial loads with a reasonable accuracy. In material characterisation, the strength of EOL tyres captured in the inflation tests were significantly larger than those obtained from direct tensile tests, which revealed the cut tyre strip could not capture the synergic effect of the embedded tyre reinforcement composites in a representative manner. The results of this study can be used by built environment professionals to design and analyse the performance of tyre encased soil and tyre walls.

Особенности расчета предела огнестойкости балок из строительных сталей

One of the main directions of research in the field of increasing the actual limits of fire resistance of steel structures is the development and implementation of fire-resistant rolled products with increased thermal stability. Fire-resistant steels are steels whose yield strength when heated to 600 °C is at least 60 % of the yield strength at 20 °C. For their wide application in construction, information is needed on the change in the strength properties of fire-resistant rolled metal products at high heating temperatures. In addition, it is required to develop a method for assessing the bearing capacity of steel structures considering the nature of the temperature distribution in their cross section. The introduction of fire-resistant steels and the proposed method of calculation will in some cases will allow to ensure the normative limit of fire resistance of load-bearing structures or reduce the cost of their fire protection. The experimental and calculated data are obtained concerning the limits of fire resistance of beams made of steel rolled metal of classes S355, S390, as well as S355P and S390P with increased heat resistance. The use of the method for calculating the fire resistance limit of bent steel structures heated from three sides considering uneven heating in the cross section, demonstrates satisfactory convergence with the experimental data for beams made of building steels, including fire-resistant ones with increased thermal stability. Various levels of static load were modeled under the influence of the temperature regime of a standard fire. The research results contribute to the introduction of new types of fire-resistant building steels for the construction of buildings from metal structures. This will increase their safety and stability in case of fire and will lead to a reduction in the construction costs.

Оценка сходимости результатов экспериментальных исследований огнестойкости сжатых железобетонных элементов с повышенным процентом армирования с численными расчетами

Introduction. Evaluation of actual fire resistance of load-bearing building structures made of various materials and reinforced concrete, in particular, encompasses a rather complex and research-intensive case of analysis of integrated, mechanical and fire safety of buildings and structures. Current methods of analyzing the fire resistance of reinforced concrete structures do not take into account any thermal characteristics of reinforcement. Hence, values of the fire resistance limit of structures can only be consistent with experimental results only if the percentage of reinforcement in analyzed concrete structures and reinforced concrete structures is below 3.5 %. The purpose of the work. Is (1) the pilot testing of a hybrid experiment method and (2) evaluation of convergence between (a) results of experimental laboratory studies on fire resistance of compressed reinforced concrete elements with a higher percentage of reinforcement, (b) theoretical data and (c) numerical calculations. The following tasks were solved: in accordance with the developed method, analytical, experimental laboratory and numerical studies of fire resistance of compressed concrete and reinforced concrete elements (including those that have a higher percentage of reinforcement) were carried out; convergence between the obtained results was evaluated; conclusions were made about the issues under consideration. Research methods. Theoretical data, applied for comparison purposes, were obtained analytically (using formulas and nomograms of SP (Construction Regulations) 468.1325800.2019), experimental and calculated data were obtained in the course of concurrent experimental studies conducted at the fire testing laboratory of NRU MGSU, and numerical studies were obtained using the Abaqus PC software package. In the course of a laboratory experiment made using the loading equipment, the strength of reference concrete templates was identified, using the tensile machine to find the physical and mechanical characteristics of reinforcing steel. Next, reference concrete and reinforced concrete specimens with pre-set characteristics were made. Then temperature fields in concrete and cross sections of specimens, containing reinforced concrete, were identified using the thermocouple data. Centrally compressed concrete and reinforced concrete specimens were tested in a fire chamber at a standard fire temperature. The behaviour of concrete and reinforced concrete specimens was simulated using volumetric finite elements, having the size of up to 10 mm, and a built-in Heat Transfer Solver (Heat transfer). Temperature field distribution and fire resistance of reinforced concrete elements were analyzed at a standard fire temperature in concrete and reinforced concrete elements. Results and their discussion. The following knowledge was gained by means of this research project: convergence between temperature values at control points in concrete specimens (according to thermocouples), acceptable for practical purposes. These values were obtained in the course of experimental laboratory studies and calculations made according to current standards, which confirms the validity of the experiment; convergence between temperature values at control points in concrete specimens (according to thermocouples), acceptable for practical purposes. These values were obtained in the course of experimental laboratory studies and calculations made according to current standards, which confirms the validity of the proposed hybrid experi­ment method and the trustworthiness of the research; a great difference reaching 10 to 30 % (19.3 % on average for a group of specimens) between experimental and analytical values of fire resistance of reinforced concrete elements, which proves the hypothesis about a reduction in the heating temperature of concrete in a reinforced concrete section if the thermal influence of reinforcement is taken into account; convergence between fire resistance values (the difference is 7 to 10 %) in reinforced concrete specimens, which is acceptable for practical purposes. These values were obtained in the course of experimental laboratory studies and calculations, and their convergence proves the applicability of the proposed hybrid experi­ment method with account taken of the hypothesis about less intensive heating of concrete, if the thermal impact of reinforcement is taken into account. Conclusions. The hypothesis about a reduction in the heating temperature of concrete in the reinforced concrete section that has a high percentage of reinforcement (more than 3.5 %) was proven, taking into account the thermal influence of reinforcement. The consequence is the underestimated values of fire resistance of reinforced concrete elements, identified in accordance with a standardized approach. The applicability of the proposed hybrid experiment technique is also proven, taking into account the hypothesis about a reduction in concrete heating due to the thermal influence of reinforcement.

Near-zero thermal mismatch flexure metastructure with high-resonant frequency

Heterogeneous mechanical metastructures, especially fabricated by additive manufacturing techniques, have attracted attention in lightweight multifunctional material engineering. Near-zero thermal expansion materials play an important role in precision equipment. However, undesired thermal mismatch flexure distortion occurs when the precision equipment is mounted on the main load-bearing structures of spacecraft and the environmental temperature changes. The present study presents a near-zero thermal mismatch flexure metastructure, including the design strategy inspired by plants with axisymmetric distributing anisotropic microstructures, the thermal deformation constitutive relation derived by the flexibility method, and the fabrication of this metastructure by selective laser melting. Thermal deformation experiments demonstrate that the coefficient of thermal flexure reduces by 92.4% compared with traditional bi-material plates connected by screws. Mechanical vibration experiments demonstrate that the fundamental resonant frequency of this metastructure can be as high as 956 Hz, which is 5.8 times larger than the common requirements of functional components for spacecraft to avoid mechanical resonance with the main structure during launch. The excellent thermal mismatch shape stability and high-resonant frequency properties make it a potential candidate for thermal geometric stable structures working in variable thermal and mechanical environments.

Adhesion of batch hot-dip galvanized components

Structural bonding of batch hot-dip galvanized components poses a particular challenge against the background of the build-up of the zinc coating in the form of different zinc-iron phases. As part of a research project, parameters influencing the zinc coating, the pre-treatment of the zinc substrate, and the adhesive were investigated with regard to the load-bearing capacity of a bonded joint. The variation of the zinc coatings was achieved by using four different steel grades in combination with four batch galvanizing processes. Therefore, small-scale, thick shear tensile specimens were uniformly fabricated, galvanized, bonded in pairs, and mechanically tested. A second series of tests was aimed at the feasibility of an adhesive bond of batch galvanized, medium-scale components under realistic boundary conditions. The test specimens were produced by varying the surface preparation and the adhesive and tested mechanically to shear failure. The results of both test series show that zinc-coated components can be adhesively bonded well and reliably, and, by this, a high load-bearing capacity can be achieved in the bonded joint. The small-scale tests clearly show that the type of zinc coating and its structure obviously have a significant influence on the load-bearing capacity. In summary, it can be stated that the relevant material and process-related influences on the shear load-bearing behavior of bonded joints of batch hot-dip galvanized components were demonstrated by means of the two test series, and the basis for implementing such joints on real load-bearing structures was laid. The presented procedure (small-scale tests and component tests) can be used as a suggestion for a later application in practice.

Improved Fly Ash Based Structural Foam Concrete with Polypropylene Fiber

The direction of construction science that is associated with the development of the theory and practice of creating a new generation of foam concrete is particularly interesting and relevant. The development of improved structural foam concrete using polypropylene fiber and industrial waste, namely fly ash (FA), is prompted by the existing environmental threat posed by FA; this threat is a result of the operation of the fuel energy industry, as well as the possibility of using foam concrete not only as thermal insulation, but as the main material for load-bearing structures that have a certain level of responsibility. The aim of this work was to create and optimize the recipe technological parameters to produce non-autoclaved fiber foam concrete (FFC) using FA as a component. The study used standardized methods for assessing the properties of FFC, and the method of optical microscopy to analyze the structural characteristics of the material. It has been revealed that the replacement of cement with FA in an amount of 10% to 40% helps to reduce the dry density (DD) of FFC. The lowest DD was recorded for samples with 40% FA. The best results for the compressive strength (CS) and flexural strength (FS) were recorded for FFC samples with 10% FA instead of cement. The increase in CS was 12%, and the increase in FS was 23%. The best thermal insulation properties of FFC, and in terms of resistance to freezing and thawing, were recorded in samples with a 10% replacement of cement with FA. The maximum decrease in thermal conductivity was 14%.

Formalization of decision-making procedures regarding the extension of the operation term of railway rolling stock in the conditions of post-war development of Ukraine

Summary: Today, the vast majority of the railway transport fleet in Ukraine has reached the end of its service life, set by the manufacturer. One of the ways to solve the problem of aging rolling stock, along with the purchase of new wagons and locomotives, remains the extension of the service life of passenger wagons due to the restoration of their resource during appropriate repairs. However, the extension of the service life of rolling stock in Ukraine is regulated by a large number of documents (more than a dozen). Since information is scattered in various sources, the need to consider many criteria regarding the possibility of extending the service life of various types of railway rolling stock units creates certain difficulties in perceiving information and takes time to make a decision on the appointment of the necessary type of repair. One of the solutions to the problem of decentralization of the regulatory framework, along with its change, is its formalization for further development of automated decision-making systems in this area. The paper proposes the classification of passenger wagons of locomotive traction (as the most difficult case) by type and place of production from the point of view of the issue of continuing operation beyond the period established by the manufacturer. An algorithm has been developed for the exact calculation of the difference between dates (construction, repair history, and the maximum period of operation), ensuring compliance with regulatory documents, and based on it, software that allows to determine the existence of grounds for extending the term as quickly as possible in the conditions of technical diagnostics using a smartphone operation of the load-bearing structures of locomotive traction passenger wagons and calculate the type of repair that must be scheduled according to the calendar period

Thin-Layer Fibre-Reinforced Concrete Sandwich Walls: Numerical Evaluation

In this study, structural thin-layer sandwich walls (SWs) made of steel-fibre-reinforced concrete (SFRC) without conventional reinforcements were investigated. Other researchers have shown that SWs with thin wythes can be used as load bearing structures in low-rise buildings, thereby reducing the amount of concrete by 2–5 times if compared to conventional reinforced-concrete SWs. In most studies, relatively warm climatic regions are the focus, and thin-layer SWs with shear connectors to obtain a certain level of composite action are investigated. In almost no studies has sound insulation been evaluated. In this study, a numerical investigation of structural, thermal and sound insulation performances was carried out. The load-bearing capacities of composite and non-composite SWs are compared. Regions with the lowest five-day mean air temperature of −20 ∘C were considered. The characteristics of the SW are compared to the requirements given in relevant European and Latvian standards. The minimum thermal insulation for family houses varies from 120 mm to 200 mm, depending on the material. To ensure sufficient sound insulation, the average thickness of the concrete wythes should be around 60 mm, preferably with a 15 mm difference between them. Structural analysis of the proposed wall panel was performed using non-linear finite element analysis software ATENA Science. The obtained load-bearing capacity exceeded the design loads of a single-story family house by around 100 times, regardless of the degree of composite action.

Geodetic Measurement of Deformations of Load-Bearing Supports and Structures of the Komarovsky Market Building during its Operation

Komarovsky market is the largest covered market in Belarus and Europe. It started working in 1980. Until 2000, the operation of the market building was carried out without taking into account the uniqueness and increased requirements for objects of such type. The technical conditions and operating rules for the precast-monolithic reinforced concrete pavement shell with dimensions of 103´103 m have not been met. This led to the fact that individual elements were in a pre-emergency state. Scientists and specialists of the Belarussian State Polytechnical Academy carried out work on the examination of the technical condition and operational suitability of the Komarovsky market building. It is recommended to carry out geodetic control of coating shell deflections, deformations of side elements and supports at least once a quarter. To do this, a geodetic planned and high-altitude justification was created along the perimeter of the market building and on its mezzanines, from which deformations of the coating shell and side elements were measured. Therefore, the height position of the mezzanines was checked by the class-IV leveling. For mathematical processing of the results of high-precision geodetic observations in the Visual Basic language of the Excel editor, a complex “Geodetic Programs” was compiled, which is located on the Belarusian National Technical University website and in the local network of the University. For 21 years, the software package has been used by the authors not only to solver scientific and production problems, but also in the educational process. It is advisable to introduce programs in other educational institutions and industrial enterprises of the Republic of Belarus to solve the problems of engineering geodesy. The settlement measurements of the pile foundations of the market building were carried out by the class-II geometric leveling using КоNi 007 instrument. The coating shell deflections were determined by trigonometric leveling with a 2Т2 theodolite and a Leica TCR 1201 electronic tacheometer according special technique. An accuracy of the order of 1–2 mm was ensured by short sighting beams. The displacements of the onboard elements were measured with a theodolite and electronic tacheometer using the polar method and circular technique. During the geodetic control, the measured values of deflections of the coating shell, deformations of the side elements and pile supports did not exceed the established tolerances, which indicates the stability of all load-bearing structures of the Komarovsky market building.

Algorithm for designing load-bearing structures of a multi-storey building using the visual programming environment DYNAMO STUDIO

Objective. The article is devoted to the actual problem of minimizing the designer's work time using Dynamo Studio as a powerful tool for automating design tasks.Method. A description of some of the possibilities of the Dynamo Studio visual programming environment when developing a building project in the Revit software package is given.Result. Dynamo scripts work methods are presented and described, which allow to significantly speed up the processes of modeling and preparation of project documentation. The principles of information modeling make it possible to increase the speed of the project work being carried out without adversely affecting its quality. This makes it possible to avoid a wide range of design errors, which in the future will not lead to corresponding problems during the construction phase of the facility. The results of the application of the developed algorithms for the automated construction of a three-dimensional model of a multi-storey building are presented.Conclusion. Using the visual programming environment allows you to create an information model that updates its configuration when the elements included in it change.

Rapid assessment of out-of-plane nonlinear shear stress–strain response for thick-section composites using artificial neural networks and DIC

Thick-section fiber-reinforced polymer matrix composites (TSCs) have been increasingly used in primary and secondary load-bearing structures. Due to complex deformation mechanisms, accurate out-of-plane constitutive relations, including nonlinear shear stress–strain response, are required for structural analysis and failure prediction of TSC structures. A plate torsion test is proposed to assess the nonlinear out-of-plane shear stress–strain response using an artificial neural network (ANN) and digital image correlation (DIC). The ANN model was developed using three-dimensional finite element numerical simulations, and the out-of-plane shear stress was obtained with good accuracy. The efficiency of the shear stress calculation has been improved. The usability of the test method has been refined substantially. A comparison of the shear stress with the FEM-calculated result showed that the average error of the ANN-predicted shear stress was less than 0.5%. Accordingly, the constitutive parameters of a 15-ply thick S6C10/AC318 glass/epoxy unidirectional tape panel have been extracted from the minimization of the normalized error between ANN-calculated shear stress and DIC-measured shear strain iteratively. The efficiency of stress updating for the plate-torsion specimen has been improved by 105 times to extract the material constitutive parameters. Not limited to plate-torsion specimens, the proposed ANN-DIC method can be extended further for rapid assessment of material constitutive parameters for other anisotropic polymer-based composite materials using complex, statically indeterminate tests.

Assessment of the effects of strong earthquakes on the city of Plovdiv

The assessment of the effects of strong earthquakes is based on procedures for integrating the seismic hazard and the seismic vulnerability of the load-bearing structures of the building stock. The analyses are made for seismic excitation, determined by the analysis of seismic hazard - a deterministic earthquake scenario (expressed in macroseismic intensity). The scenario takes into account the effects of soil amplification, using the geotechnical information for the considered urban area. Based on the collected information about the building stock and the performed analysis, an assessment of the direct damages and destructions is obtained. The distribution of the buildings is graphically presented, respectively by number and by total built-up area, at different degrees of damage. Economic losses are calculated based on the results obtained for damage and destruction in three main groups of buildings. The main task of this study is to quantify the effects of strong earthquakes for the city of Plovdiv based on an accurate assessment of seismic hazard. This information will enable the municipal administration to make informed management decisions about planning of rescue equipment and people, hospital beds, shelter for the homeless people and financial resources to restore the damaged buildings.

Comparative Studies of 3D Printing with Conventional System in Load Bearing Structure

Abstract: With the use of software, structures may now be built entirely out of concrete by 3D printing them in layers. With the use of this technology, even complex geometric structures, massive loadbearing structures, and hydraulic structures may be quickly and cheaply created. During construction, it doesn't require any additional formwork, and the amount of labour needed is also rather low. It is an environmentally friendly technology that can also be utilised for decorative purposes. Charles Hull created this technology in 1984. This article discusses current trends and approaches for employing 3D printers in the construction industry. Angle of twist per floor for various storeys.

EXPERIMENTAL STUDY OF SNOW LOAD DISTRIBUTION ON A SHELL OF THE GRAND SPORTS ARENA OF LUZHNIKI OLYMPIC COMPLEX

Introduction. The mechanism of the formation of snow deposits on the shell of the Luzhniki GSA and their redistribution in winter were established on the basis of the data obtained during the monitoring of the snow load for over 20 years.Aim. In this article, the mechanism of the formation of snow deposits and their distribution on the shell of the Luzhniki GSA were determined, along with the numerical values of the form factor μ characterizing the transition from the ground snow load to the snow load on the shell.Materials and methods. The measurements of the load and density of snow deposits on the shell of the Luzhniki GSA were carried out from 1998 to 2019. The obtained results were compared with the parallel measurements of ground snow load (GSL) in Luzhniki. In addition, the snow load, as well as statistical data analysis on the maximum annual values of the GSL, were analyzed using the hydrometeorological data of decadic snow surveys in Moscow, performed by the V.A. Mikhelson Meteorological Observatory following the dates of field measurements. The graphs of the repeatability of wind directions for the month preceding the observation dates were plotted.Results. The maximum values of the form factor μ for each section of the shell were obtained. The areas characterized by increased snow deposition on the shell during various periods of snow accumulation andthe dependence of their formation on wind speeds and directions in winter were revealed. Graphs depicting the distribution of snow load on the surface by observation years were plotted. It was established that the values of snow loads on the GSA shell during the observation period generally lay within the design values, except for local zones near the internal contour during the installation of the canopy.Conclusion. It was shown that the formation, accumulation, and redistribution of snow deposits on the shell comprise a complex and uneven process, varying from winter to winter. When selecting the analytical models of snow loads for calculating unique load-bearing structures, it is necessary to account for the most unfavorable wind flow directions, at which an uneven snow deposition pattern occurs, as well as the physical properties of the shell and field observations.

Gene expression profiling of the masticatory muscle tendons and Achilles tendons under tensile strain in the Japanese macaque Macaca fuscata.

Both Achilles and masticatory muscle tendons are large load-bearing structures, and excessive mechanical loading leads to hypertrophic changes in these tendons. In the maxillofacial region, hyperplasia of the masticatory muscle tendons and aponeurosis affect muscle extensibility resulting in limited mouth opening. Although gene expression profiles of Achilles and patellar tendons under mechanical strain are well investigated in rodents, the gene expression profile of the masticatory muscle tendons remains unexplored. Herein, we examined the gene expression pattern of masticatory muscle tendons and compared it with that of Achilles tendons under tensile strain conditions in the Japanese macaque Macaca fuscata. Primary tenocytes isolated from the masticatory muscle tendons (temporal tendon and masseter aponeurosis) and Achilles tendons were mechanically loaded using the tensile force and gene expression was analyzed using the next-generation sequencing. In tendons exposed to tensile strain, we identified 1076 differentially expressed genes with a false discovery rate (FDR) < 10-10. To identify genes that are differentially expressed in temporal tendon and masseter aponeurosis, an FDR of < 10-10 was used, whereas the FDR for Achilles tendons was set at > 0.05. Results showed that 147 genes are differentially expressed between temporal tendons and masseter aponeurosis, out of which, 125 human orthologs were identified using the Ensemble database. Eight of these orthologs were related to tendons and among them the expression of the glycoprotein nmb and sphingosine kinase 1 was increased in temporal tendons and masseter aponeurosis following exposure to tensile strain. Moreover, the expression of tubulin beta 3 class III, which promotes cell cycle progression, and septin 9, which promotes cytoskeletal rearrangements, were decreased in stretched Achilles tendon cells and their expression was increased in stretched masseter aponeurosis and temporal tendon cells. In conclusion, cyclic strain differentially affects gene expression in Achilles tendons and tendons of the masticatory muscles.

Revealing the Innovations in Late Medieval Roof Structures of Finland

Abstract In Scandinavia and Finland, nearly all constructions, including monumental and sacral architecture, used only timber until the 11th century. In Finland, timber remained the dominant construction material until the 19th century. Due to many fires, wars, and other catastrophic events, the number of still-standing wooden buildings and constructions erected before industrialization is very limited. Medieval wooden buildings can only be found in archaeological excavations, and the last remaining medieval load-bearing wooden structures are preserved in the medieval stone churches. While medieval roof constructions have been widely researched elsewhere in Europe, a comprehensive understanding of medieval roof constructions in Finland is largely lacking. This article presents an ongoing study of roof structures in Finnish medieval stone churches, focusing on two churches, Pernaja and Hammarland, which provide evidence of the transition from tie beam roof trusses to roof trusses without a tie beam. We examine the typology of the trusses, and present new results based on a comparison of the churches and dendrochronological analyses. Finally, we discuss possible explanations for the structural innovations and the emergence of the roof truss without a tie beam in a wider cultural context.