Heavy Building Research Articles

Petrography and geomechanical properties of some mine waste rocks from the Tarkwaian Group in Ghana: implications for their use as aggregates in general engineering works

This research investigated some mine waste rocks from the southwestern part of the Tarkwaian Group in Ghana to check their suitability for general engineering works using petrography and geomechanical characteristics of the rocks. The rocks were subjected to a total of ten (10) tests, including Aggregate impact value (AIV), Aggregate crushing value (ACV), Loss Angeles abrasion (LAA), Specific gravity (SG), and Water absorption (WA), as well as flakiness and elongation index, slake durability (SD), chloride test (CT), sulphate test (ST), and ten percent fines (TPF). The tests were carried out per the American Society for Testing and Materials guidelines (ASTM). The following average test results were obtained: AIV (7.12%), ACV (15.60%), LAA (23.16%), TPF (269.7 kN), sulphate (0.0215%), chloride (0.00123%), flakiness (39.5%) and elongation (39.4%). The mine waste rocks are dominated by quartz and sericite, according to the petrographic examination and thus, can be classified as quartzites. Except for the flakiness and elongation index tests, all the results were consistent with the ASTM standards. The analysis carried out on the selected mine waste rocks from the southwestern part of the Tarkwaian Group could be catastrophic for heavy engineering works such as roads, bridges, and heavy buildings but can be used for pavements, lightweight buildings, monuments, and decoratives due to the percentage of quartz present to compensate for the weakness posed by the sericite.

1899年紀伊・大和地震の被害に関する文献調査

Literature survey on damage due to the 1899 Kii-Yamato earthquake was carried out continuing to the previous paper of the 1936 Kawachi-Yamato event. This earthquake had rather deep focal depth as 50km and caused moderate damage in wide areas of Kinki district. Detailed damage was picked up from the reports and newspaper articles at that time. These data were sorted by municipalities in table and mapped. Heavy building damage was limited in focal area but damage to brick masonry factory buildings including chimneys is dominated in Osaka. In mountainous areas landslides and rockfalls occurred and caused casualties.

Experimental study of the thermal behavior of PCM and heavy building envelope structures during summer in a temperate climate

The main objective of the study was to evaluate the effects of PCM and traditional masonry construction on the summer thermal performance of the non-air-conditioned residential building in a temperate climate. The research was conducted in three rooms. In the first case, the lightweight frame construction of the walls and ceiling was covered with gypsum board on the inside, while in the second, a layer of Rubitherm® RT25HC was placed. The third room used masonry walls and a reinforced concrete roof. All rooms had identical flooring. The study was conducted between 13.08 and 18.09.2020. For the night period, various rates of mechanical ventilation were used to maintain the room temperature within the range of optimal PCM melting temperatures. The results of the study indicate significantly higher effectiveness of traditional high thermal capacity building materials than PCMs for lowering high indoor temperatures in summer. This occurs when there is a marked increase in outdoor temperature on at least one day, while at the same time the indoor temperature does not significantly exceed the PCM's melting temperature range specified by the manufacturer. Studies have further shown that the cooling efficiency of PCMs remains at a reasonably high level only for a small number of days in summer. This occurs when there is a marked increase in outdoor temperature on at least one day, while at the same time the indoor temperature does not significantly exceed the PCM's melting temperature range specified by the manufacturer.

Quantitative strong motion simulations at three locations in downtown Mashiki during the 2016 Kumamoto Earthquake (Mw 7.0) based on the nonlinear ground response analyses with soil liquefaction

The mainshock of the 2016 Kumamoto Earthquake (Mw 7.0) caused extensive damage to buildings in downtown Mashiki, Kumamoto Prefecture, Japan. The heavy building damage in the area was associated with both strong ground motion and building response characteristics. Fortunately, there were two strong motion stations in the area and the observed records during the mainshock were distributed, showing peak ground velocities exceeding 100 cm/s on the surface. The level of shaking would be sufficient to make soft surface sediments nonlinear. To reproduce observed ground motions quantitatively, one-dimensional nonlinear effective-stress time-history analyses were conducted at three locations in downtown Mashiki. The input wave was employed as either the observed underground wave or simulated outcrop input motion based on the diffuse field theory. The main purpose of the study was twofold: to investigate the proper soil constitutive relationship and its nonlinear parameters based on the limited amount of in situ information, and to validate the method of input motion evaluation at the seismological bedrock level based on diffuse field theory. The nonlinear time history analyses using the on-site boring survey and the outcrop wave based on diffuse field theory showed that the waveform of the mainshock observed on the ground surface was explained with sufficient accuracy. In addition, the results of the effective stress analysis indicated that soil liquefaction might have occurred in the area with thick surface layers along the Akitsu River where the water table was considered to be quite shallow.Graphical

Physics-informed neural networks for building thermal modeling and demand response control

Buildings energy consumption constitutes over 40% of the total primary energy consumption, and buildings can provide potential energy flexibility for the grid. In the grid with high penetration of renewable energy, a control-oriented model with accurate prediction and prompt response is crucial for better load management. However, developing such a model is still a big challenge for grid-integrated buildings due to the limitations of current modeling approaches. Physics-based models commonly represent a specific building while customization for each building remains a daunting task; meanwhile, data-driven models, though easier to develop, require a large amount of data and are not well generalized for other buildings. Thus, we propose a novel model based on a physics-informed neural network dubbed as PhysCon, which combines the interpretable ability of physical laws and the expressive power of neural networks for control-oriented demand response of grid-integrated buildings. Specifically, a Resistance-Capacitance (2R2C) thermal model is adopted to express the knowledge of building physics, and a full-connected neural network is developed to learn the information from actual data. We demonstrate the prediction performance of PhysCon using actual building physics parameters and on-site measured data from an experimental platform that contains two detachable rooms. Two different internal thermal mass scenarios, namely light and heavy mass, were designed to demonstrate the power of PhysCon for buildings with different levels of demand response potentials. The results show that PhysCon outperforms the purely data-driven model in predicting the room temperature and thermal load demand for both light and heavy buildings. Moreover, building thermal mass is an efficient and free demand response resource for grid-integrated buildings. The proposed PhysCon model can be conveniently and efficiently deployed in the energy management system of buildings, owing to its simplicity and generalization.

Experimental Study of Envelope Airtightness in New Egyptian Residential Dwellings

In residential buildings, air infiltration impacts energy, indoor air quality, and thermal comfort considerably. While air infiltration in residential buildings has been the focus of many studies, most published field-testing results pertain to developed countries, with little or no data on air infiltration in developing nations. This paper presents the results of one of the first field investigations into envelope infiltration in the residential buildings of the hot-arid climatic area of Egypt. To analyze the air permeability of the building envelope, the fan pressurization method, often known as the blower door test (BDT), is used, following ISO 9772. The study focuses on 20 residential dwellings built with heavy construction materials and subjects them to extensive characterization and testing. The average air leakage and the air permeability rate for the tested sample were 6.14 h−1 and 17.3 m3/(h∙m2), respectively. However, significant variations in airtightness were observed across the dwelling, leading the team to test several building-related parameters statistically to study their impact on airtightness. Fenestration quality appeared to be a critical factor in determining air infiltration, showing a strong correlation with the air change and leakage. A further investigation underscored that the specific aperture factor and the fenestration quality can predict the infiltration rates to a large degree. Thus, we recommend further investigation of these characteristics in heavy construction material building. Finally, we strongly recommend that building codes in developing countries such as Egypt include minimum performance requirements for fenestration.

Green industrial buildings in Vietnam from experts’ point of view

In recent years, there has been a remarkable rise in the number of certified green building projects in Vietnam, with industrial buildings accounting for the largest portion. The purpose of this research is to evaluate the ability to achieve points of industrial buildings in some green building systems under specific conditions of Vietnam. Another aim of the study is to point out the distinct features of industrial buildings that influence their design, including heavy industry, light industry, and industrial buildings with cleanrooms. Accordingly, this will contribute to increasing the number of industrial buildings that achieve green certification in the future. The study uses a mixed-methods approach, including expert interviews, field surveys, and meta-analysis. The research results will serve as a reference document for sustainable development-oriented design consultants and for organizations establishing green construction criteria systems to be able to upgrade to newer versions with higher adaptability for industrial works.

The essential properties governing the appropriate selection of phase change materials integrated into heavy structure buildings

This paper examines the essential properties governing the appropriate selection of phase change materials (PCMs) integrated into heavy structure buildings during different seasons. Nine PCMs with various thermophysical properties were evaluated, in the free-floating mode, under hot and dry climate conditions. The practical examined range of each property is extracted from the data of the nine considered PCMs. An indoor experiment was designed and constructed to validate the simulation models created with the EnergyPlus and Designbuilder building simulation programs. The results confirm that the large latent heat of fusion and low thermal conductivity of PCMs enhance the indoor thermal comfort at the same melting temperature. The Intensity of Thermal Discomfort (ITD) decreases from 51 to 36.4% as the energy density increases from 138.6 to 180.6 MJ/m3, for two PCMs with a melting temperature of 21 °C. As the PCM melting temperature increased from 21 to 29 °C, the ITD index decreased from 27 to 10 °C.day. Thus, the occupants’ thermal comfort enhances as the PCM melting temperature approaches the upper limit of the adaptive thermal comfort. In brief, the ITD sensitivity index (the relative change in ITD due to a relative change in PCM property) is highly affected by the PCM melting temperature (5.85), followed by latent heat (1.37), density (0.71), thermal conductivity (0.41), and the phase transition region (0.096) that has a negligible effect on the indoor thermal comfort.

HT-SIP: a semi-automated stable isotope probing pipeline identifies cross-kingdom interactions in the hyphosphere of arbuscular mycorrhizal fungi

BackgroundLinking the identity of wild microbes with their ecophysiological traits and environmental functions is a key ambition for microbial ecologists. Of many techniques that strive for this goal, Stable-isotope probing—SIP—remains among the most comprehensive for studying whole microbial communities in situ. In DNA-SIP, actively growing microorganisms that take up an isotopically heavy substrate build heavier DNA, which can be partitioned by density into multiple fractions and sequenced. However, SIP is relatively low throughput and requires significant hands-on labor. We designed and tested a semi-automated, high-throughput SIP (HT-SIP) pipeline to support well-replicated, temporally resolved amplicon and metagenomics experiments. We applied this pipeline to a soil microhabitat with significant ecological importance—the hyphosphere zone surrounding arbuscular mycorrhizal fungal (AMF) hyphae. AMF form symbiotic relationships with most plant species and play key roles in terrestrial nutrient and carbon cycling.ResultsOur HT-SIP pipeline for fractionation, cleanup, and nucleic acid quantification of density gradients requires one-sixth of the hands-on labor compared to manual SIP and allows 16 samples to be processed simultaneously. Automated density fractionation increased the reproducibility of SIP gradients compared to manual fractionation, and we show adding a non-ionic detergent to the gradient buffer improved SIP DNA recovery. We applied HT-SIP to 13C-AMF hyphosphere DNA from a 13CO2 plant labeling study and created metagenome-assembled genomes (MAGs) using high-resolution SIP metagenomics (14 metagenomes per gradient). SIP confirmed the AMF Rhizophagus intraradices and associated MAGs were highly enriched (10–33 atom% 13C), even though the soils’ overall enrichment was low (1.8 atom% 13C). We assembled 212 13C-hyphosphere MAGs; the hyphosphere taxa that assimilated the most AMF-derived 13C were from the phyla Myxococcota, Fibrobacterota, Verrucomicrobiota, and the ammonia-oxidizing archaeon genus Nitrososphaera.ConclusionsOur semi-automated HT-SIP approach decreases operator time and improves reproducibility by targeting the most labor-intensive steps of SIP—fraction collection and cleanup. We illustrate this approach in a unique and understudied soil microhabitat—generating MAGs of actively growing microbes living in the AMF hyphosphere (without plant roots). The MAGs’ phylogenetic composition and gene content suggest predation, decomposition, and ammonia oxidation may be key processes in hyphosphere nutrient cycling.1Ep-TvDfGR-SFqLGobimTCVideo

Mapping Local Climate Zones in the Urban Environment: The Optimal Combination of Data Source and Classifier.

The novel concept of local climate zones (LCZs) provides a consistent classification framework for studies of the urban thermal environment. However, the development of urban climate science is severely hampered by the lack of high-resolution data to map LCZs. Using Gaofen-6 and Sentinel-1/2 as data sources, this study designed four schemes using convolutional neural network (CNN) and random forest (RF) classifiers, respectively, to demonstrate the potential of high-resolution images in LCZ mapping and evaluate the optimal combination of different data sources and classifiers. The results showed that the combination of GF-6 and CNN (S3) was considered the best LCZ classification scheme for urban areas, with OA and kappa coefficients of 85.9% and 0.842, respectively. The accuracy of urban building categories is above 80%, and the F1 score for each category is the highest, except for LCZ1 and LCZ5, where there is a small amount of confusion. The Sentinel-1/2-based RF classifier (S2) was second only to S3 and superior to the combination of GF-6 and random forest (S1), with OA and kappa coefficients of 64.4% and 0.612, respectively. The Sentinel-1/2 and CNN (S4) combination has the worst classification result, with an OA of only 39.9%. The LCZ classification map based on S3 shows that the urban building categories in Xi’an are mainly distributed within the second ring, while heavy industrial buildings have started to appear in the third ring. The urban periphery is mainly vegetated and bare land. In conclusion, CNN has the best application effect in the LCZ mapping task of high-resolution remote sensing images. In contrast, the random forest algorithm has better robustness in the band-abundant Sentinel data.

Sludge-incinerated ash based shape-stable phase change composites for heavy metal fixation and building thermal energy storage

Incineration is a harmless way to treat municipal sludge. However, it is difficult to fix heavy metals in the sludge-incinerated ash (SIA). To fix the heavy metals and recycle the SIA effectively, this work innovatively proposed the SIA as skeleton material, and five shape-stable phase change composites (SSPCCs) with different mass ratios of SIA to NaNO3 (phase change material, PCM) were fabricated via the cold-compression & hot-sintering (CCHS) method. Then, key thermal performance, mechanical strength, and micromorphology were investigated while the chemical compatibility between the SIA components and NaNO3 was analyzed. Results showed that the SSPCCs could fix the heavy metals properly, and the SIA was suitable for skeleton material; The SSPCC with the mass ratio 5:5 of SIA to NaNO3 reached a maximal thermal energy storage (TES) density of 409.25 kJ/kg in the range of 100–400 °C, which had high mechanical strength of 139.65 MPa and good thermal stability; The SIA components demonstrated excellent chemical compatibility with NaNO3.

A new early branching armored dinosaur from the Lower Jurassic of southwestern China.

The early evolutionary history of the armored dinosaurs (Thyreophora) is obscured by their patchily distributed fossil record and by conflicting views on the relationships of Early Jurassic taxa. Here, we describe an early diverging thyreophoran from the Lower Jurassic Fengjiahe Formation of Yunnan Province, China, on the basis of an associated partial skeleton that includes skull, axial, limb, and armor elements. It can be diagnosed as a new taxon based on numerous cranial and postcranial autapomorphies and is further distinguished from all other thyreophorans by a unique combination of character states. Although the robust postcranium is similar to that of more deeply nested ankylosaurs and stegosaurs, phylogenetic analysis recovers it as either the sister taxon of Emausaurus or of the clade Scelidosaurus+ Eurypoda. This new taxon, Yuxisaurus kopchicki, represents the first valid thyreophoran dinosaur to be described from the Early Jurassic of Asia and confirms the rapid geographic spread and diversification of the clade after its first appearance in the Hettangian. Its heavy build and distinctive armor also hint at previously unrealized morphological diversity early in the clade's history.

Kanaky New Caledonia

Kanaky New Caledonia Mathias Chauchat (bio) The year 2020 left Kanaky New Caledonia in a worrying situation, with an economic crisis linked to the pandemic, rising debt, and the country's 2022 budget not being approved and a yes/no referendum that placed two camps in an almost equal face-off. Turnout in the 2020 referendum was overwhelming at 85.69 percent, and out of 180,799 registered voters, 53.26 percent voted no to independence and 46.74 percent voted yes (High Commission of the French Republic in New Caledonia 2020). Adding to these troubles, as 2021 began, the tension around the sale of Vale's Southern nickel processing plant became increasingly violent. However, the country showed resilience. In March, an agreement was reached on the Southern plant, ending roadblocks and demonstrations across New Caledonia. Despite the covid-19-linked bereavements, the country's health-care system held up well against the disease, and good progress was made with vaccination. Further, all institutions (Congress, customary Senate, and government) were renewed to the advantage of the pro-independence parties. Nevertheless, a dark shadow hung over the picture: the French State and the nonindependentists demanded a rapid third referendum to remove uncertainties—as early as December 2021 instead of October 2022, as provided for in the Nouméa Agreement—resulting in massive nonparticipation of the independentists. The Nouméa Accord ended in a huge mess. In 2021, the multinational company Vale pushed hard to sell its 95 percent share in the Southern hydrometallurgical complex, the remaining 5 percent belonging to the Société de Participation Minière du Sud Calédonien (spmsc, South New Caledonian Mining Holding Company), a holding company run by the three New Caledonian provinces. Above all, Vale demanded a radical change in strategy: in addition to [End Page 466] the export of a less processed product (nickel hydroxide cake), it demanded access to the mineral reserves of Goro saprolites, richer in content than laterites, for export. Vale required this access to the mine to balance its finances and to find a buyer. This would be a very serious blow to the "nickel doctrine" supported by the pro-independence parties, which stipulates that the ore must be transformed rather than sold raw. Political conflict was inevitable. The situation became violent at the end of 2020 and reached its climax in early 2021. Vale drew up a report on the impacts of this violence on 1 February: more than two billion cfp francs in direct destruction onsite and at least five times that in indirect damage (us$1 = about 107.23 cfp francs). Heavy mining machinery, vehicles, tires, oil stocks, and buildings were set on fire. Forty-eight people came under judicial investigation (La Première 2020). However, on 4 March, a "political agreement" on the proposed sale of Vale NC was signed between the Southern Province and the Usine du Sud = Usine Pays (Southern Plant = Country's Plant) collective, which unites customary chiefs, environmental groups, trade unionists, and members of the independence coalition Front de Libération Nationale Kanak et Socialiste (flnks), ending six months of violent mobilization. This agreement was the first of its kind, leading to the emergence of a new mining model involving the rental rather than sale of mining titles to the operator. Vale NC sold its titles to a new structure representing New Caledonian interests, which then leased them to the new operator, Prony Resources (associated with the Swiss multinational company Trafigura). In other words, these mining titles, which are worth more than 50 billion cfp francs, belong to a local company, Sud Nickel, a subsidiary of PromoSud (which is owned by the Southern Province). Prony Resources is governed by four shareholding entities: the spmsc (30 percent), which represents the three provinces; Fidal fiducie (21 percent), which represents Prony Resources employees and the local population; Trafigura (19 percent); and Compagnie Financière de Prony (30 percent), which represents factory executives and investors (Prony Resources 2022). Together, spmsc and Fidal fiducie hold a 51 percent share, while Trafigura and Compagnie Financière de Prony (ie, the private sector) hold only a 49 percent share. Vale Canada, owner of 95 percent of Vale Nouvelle-Cal...

Determination of seismic isolation effects on irregular RC buildings using friction pendulums

This study aims to evaluate influences of isolation made using friction pendulum type isolators on seismic behavior of irregular mid-rise RC frame buildings without shear walls. For this at first, a 4-storey 3D reference building model which have no irregularity is designed as residential building. Afterwards, models including heavy overhang, short column and soft storey irregularities are created through the reference building. A total of 88 nonlinear time history analyses of regular and irregular building models subjected to 11 pairs of ground motion records are performed for non-isolated and isolated cases. There has been a significant reduction in base shear ratios for isolated reference and irregular buildings. Roof drift ratios of isolated-base models are generally higher compared to fixed-base models for both regular and irregular buildings. Unlike the results of roof displacement demands, lower average interstorey drift ratios have been obtained for especially isolated reference and heavy overhang buildings. Evaluations on the effects of the isolation for floor accelerations, interstorey drift ratio (IDR) profiles and damages of structural elements are also given in the paper. This study emphasizes that advances are made in terms of behavior against earthquakes for irregular buildings thanks to isolation.

On the Applicability of Transfer Function Models for SSI Embedment Effects

Soil-structure interaction (SSI) effects are typically neglected for relatively lightweight buildings that are less than two-three storeys high with a limited footprint area and resting on shallow foundations (i.e., not featuring a basement). However, when the above conditions are not satisfied, and in particular when large basements are present, important kinematic SSI may develop, causing the foundation-level motion to deviate from the free-field one due to embedment effects. In the literature, transfer function models that estimate the filtering effect induced by rigid massless embedded foundations are available to “transform” foundation-level recordings into free-field ones, and vice-versa. This work describes therefore a numerical study aimed at assessing potential limits of the applicability of such transfer functions through the employment of a 3D nonlinear soil-block model representing a layered soil, recently developed and validated by the authors, and featuring on top a large heavy building with basement. A number of finite element site response analyses were carried out for different seismic input signals, soil profiles and embedment depths of the building’s basement. The numerically obtained transfer functions were compared with the curves derived using two analytical models. It was observed that the latter are able to reliably predict the embedment effects in “idealised” soil/input conditions under which they have been developed. However, in real conditions, namely when a non-homogeneous profile with nonlinear behaviour under a given seismic excitation is considered, especially in presence of a basement that is more than one storey high, they may fail in capturing some features, such as the frequency-dependent amplification of the motion at the basement level of a building with respect to the free-field one.

Hydrogen farm concept: A Perspective for Turkey

Hydrogen farm concept: A Perspective for Turkey

Numerical simulation on the nonaxisymmetry arc characteristics in narrow gap TIG welding: responses to welding parameters

Narrow gap TIG welding is a high efficiency and low-cost welding technique for heavy structures building. Due to the narrow groove’s constriction, the TIG arc characteristics are different from butt welding. Understanding the unique arc characteristics of narrow gap TIG welding is the foundation for investigating the heat and mass transfer, metallurgic process, as well as process design. This research conducted numerical simulation on the TIG arc plasma in the narrow groove. The effects of welding current and arc length on the arc characteristics are investigated. Results show that, with the welding current increasing, the global velocity magnitude of plasma rises. The evolution of axial velocity and radial velocity has different responses to the current changes. The arc pressure increases drastically, and the global temperature of arc plasma also goes up. With the arc length increasing, global axial velocity rises, but the axial velocity and its gradients decrease near the anode surface. Centripetal radial velocity near the cathode increases, while centrifugal radial velocity rises at the outside of arc plasma and drops near the central axis. The maximum arc pressure on the anode surface decreases. At the lower part of the arc, arc temperature decreases near the central axis and increases at the outside of the arc.

Rubble Stone Masonry Buildings with Cement Mortar: Base Shear Seismic Demand Comparison for Selected Countries Worldwide

Full base shear seismic demand analyses with calculated examples for heavy stone masonry buildings are not present in the literature. To address this shortcoming, analyses and calculations are performed on nominally reinforced rubble stone masonry house and school designs, as typically built in Nepal. The seismic codes are literally applied for countries where the technique is still allowed (Nepal, India, China, Tajikistan, Iran, Croatia), or should be reintroduced based on current practices (Pakistan, Afghanistan, Turkey). First, this paper compares the base shear formulas and the inertia forces distributions of these codes, as well as material densities, seismic weights, seismic zoning, natural periods of vibration, response spectra, importance factors and seismic load combinations. Large differences between approaches and coefficients are observed. Then, by following Equivalent Lateral Force-principles for Ultimate Limit State verifications (10%PE50y), the base shear and story shears are calculated for a design peak ground acceleration of 0.20 g, as well as the effects of critical load combinations on the forces and moments acting on the lateral-resisting elements. It is concluded that Pakistan has the most tolerant code, Nepal represents an average value, whereas India and China are most conservative toward the case study buildings. Overall, it is observed that heavy-masonry-light-floor systems with negligible diaphragm action behave different under seismic motion than most other building typologies. Given the observations in this paper, the applicability of conventional ELF, S-ELF and S-Modal methods for heavy masonry buildings is questionable. The codes however do not introduce modified approaches that address these differences. Possible implications of the exclusion of plinth masonry and large portions of seismic weight need further assessment and validation, for which different (possibly more sophisticated) concepts must be considered, such as the equivalent frame method or distributed mass system. Since Nepal allows stone masonry in areas with higher seismic hazard levels >0.40 g (opposed to India <0.12 and China <0.15 g), their code is taken as the reference and starting point for follow-up research, which aims to verify the seismic demand by performing seismic capacity checks of the masonry piers and spandrels. The paper ends with an appeal for global collaboration under the research project SMARTnet.

Analysis of regional markets for heavy industry and machine building products (in the example of Azerbaijan economy)

The presented article analyzes regional markets, for heavy industry and machine building products for the Azerbaijani economy. In terms of trade relations and territory, the markets of Turkey, the Russian Federation, Georgia, the Islamic Republic of Iran, Moldova, Belarus, Ukraine, Kazakhstan, Kyrgyzstan, Tajikistan, Turkmenistan, Uzbekistan and Armenia were selected and evaluated. The database of the study consists of mutual import and export data for the mentioned countries in 2014–2018. Based on the import-export data collected covering the years 2014–2018 on six-digit codes of regional markets, the revealed comparative advantage and localization coefficients on import and export were calculated. As a result, importing and exporting countries have been identified in the regional markets through the calculated coefficients for each of the 5 years of heavy industry and machine building products considered. Thus, in terms of imports and exports, the countries with the highest coefficients were selected.

Calculation of thin-layer rubber-metal elements of machines and buildings considering the compressibility of the material

In some constructions with rubber-metal elements, the rubber is loaded in such a way that the hydrostatic stress is tens of times greater than the shear stress. In this case, ignoring the compressibility of rubber can lead to large errors in calculating the elastic and strength parameters of rubber parts. The elastic elements, for which consideration of the material compressibility is essential, include thin-layer rubber-metal elements, whose dimensions in plan are much larger than the thickness. Such rubber-metal elements are used for vibration and seismic protection of heavy machines, buildings and structures. In this paper, the compression of a thin-layer cylindrical rubber-metal element is considered with taking into account the compressibility of the material. In the calculation, it was assumed that the hydrostatic stress is constant over the thickness of the rubber layer, and also that the rate of change of the displacement components in the middle surface of the layer can be neglected in comparison with the corresponding speed in the direction normal to the layer. These assumptions were substantiated as a result of the analysis of the geometry of deformation and equilibrium conditions of a thin layer of rubber bonded to metal reinforcement. As a result of applying these assumptions to the solution of the problem set, a boundary value problem is obtained for an ordinary inhomogeneous linear differential equation of the second order. The corresponding homogeneous equation is solved using a power series, the coefficients of which are expressed in terms of the previous ones using a recurrent formula. Finally, a formula with a modified Bessel function of the first kind is obtained for the hydrostatic stress. The analysis of the obtained formula leads to some simplifications for different values of the dimensionless parameter, which connects the bulk modulus and shear modulus, and the radius of the cylindrical element and its thickness. The resulting axial load on the rubber element is represented by the force that would be perceived by the element in case of uniaxial deformation, i.e. if displacements in cross-sections were prohibited and compression would be performed only due to the change in volume, multiplied by a certain coefficient less than one, which takes into account the decrease in the stiffness of the element due to shear deformation. The paper also presents the results of experimental studies carried out by the authors for thin-layer cylindrical rubber-metal elements made of medium-filled rubber 2959. An example of calculating the axial load on a thin-layer element considering the compressibility of rubber is given. The obtained axial load value coincides with the experimental results with a sufficient accuracy value. Keywords: thin-layer rubber-metal element, rubber compressibility, hydrostatic stress, axial load.