Authors:Sylvio R. Bistafa Pages: 03 - 15 Abstract: Introduction: In a 1754 publication, Discussion plus particulière de diverses manières d’elever de l’eau par le moyen des pompes avec le plus grand avantage (Very detailed explanation of the different methods of raising water through pumps with the greatest effectiveness), Leonhard Euler (1707–1783) made extensive use of the concept of mechanical power in estimates of the power needed to raise waters with piston pumps, by means of natural forces such as human and horse force, running waters, and windmills. Purpose of the study: We aimed to revisit this publication to show to the modern reader Euler’s pioneering approach in providing rational calculations of the power of natural forces needed to drive different machines to raise waters with piston pumps. Methods: After a brief historical review on the use of natural forces to drive machines and the evolution of the concept of mechanical power, the method employed was the examination and an annotated reproduction of the main formulation using Euler’s original notation and ways of scientific writing of the time. Discussion: We address the evolution of hydropower and wind power, particularly for the generation of electricity, and also show that despite of its much lower attractiveness, there have been some attempts in the use of human and animal power in developing countries, particularly in applications that do not require large and constant amounts of power inputs. PubDate: 2022-03-31 DOI: 10.23968/2500-0055-2022-7-1-03-15 Issue No:Vol. 7, No. 1 (2022)
Authors:Vladimir Karpov, Evgeny Kobelev Pages: 16 - 22 Abstract: Introduction: The paper addresses thin-walled three-layer plates and panels with cutouts, reinforced with an orthogonal grid of stiffeners or rectangular reinforcement plates parallel to the coordinate lines. In this case, the thickness of the entire structure is taken into account analytically using unit column functions. Purpose of the study: We aimed to build a mathematical model of deformation and develop a method for the analysis of the stability of thin-walled elastic isotropic three-layer plates and wall panels with a discrete core. Methods: Based on the mathematical apparatus of generalized functions using the Bubnov–Galerkin method, an eigenvalue problem is solved to determine the critical parameters of a compressed three-layer wall panel with a discrete core. Results: According to the suggested method, we perform a stability analysis of three-layer wall panels with different values of core stiffness and study the impact of the discrete core parameters on the buckling load, consumption of materials, and efficiency of three-layer engineering structures. PubDate: 2022-03-31 DOI: 10.23968/2500-0055-2022-7-1-16-22 Issue No:Vol. 7, No. 1 (2022)
Authors:Huang Mingli, Shen Qiaofeng, Zhang Zhancheng Pages: 23 - 32 Abstract: Introduction: The paper addresses grouted tenon-and-groove joints in the prefabricated structure of Changchun subway station. For the first time, grouting of prefabricated structure joints with organic epoxy grouting material is analyzed. Purpose of the study: We aimed to make sure that an organic epoxy grouting material can be injected into the joints uniformly and in full and conducted its experimental study. To establish the applicability of the epoxy grouting material in the prefabricated structures, we studied the mechanical properties of the epoxy grout and its adhesive properties in relation to concrete. Methods: In the course of the study, we used a set of test equipment and an independently developed method. Results: High-quality grouting can be guaranteed at an injection pressure of 0.4 MPa and a temperature of 5–10°C. The relationship between the slurry flow rate and time was fit according to the experimental data at 5 and 10°C. The optimal quartz powder ratio was determined at the level of 1:0.6–1:0.8, and the optimal quartz powder particle size (D50) was determined at the level of 18–25 μm. The results of the study can provide references for similar projects in the future. PubDate: 2022-03-31 DOI: 10.23968/2500-0055-2022-7-1-23-32 Issue No:Vol. 7, No. 1 (2022)
Authors:Alexander Shkarovskiy, Anatolii Koliienko, Vitalii Turchenko Pages: 33 - 45 Abstract: Introduction and purpose of the study: The paper presents results of studies aimed to provide a rationale for the possibility of a gradual transition to hydrogen combustion in gas supply to domestic and commercial consumers without changes in the design and operation of burners. For this purpose, we have considered tasks of determining the indicators of interchangeability for natural gas and its mixtures with hydrogen. The main characteristics of combustible gases with various hydrogen content in a mixture have been studied. We have established the impact of the hydrogen content on the heat rate, emissions of harmful substances, as well as light back and flame lift phenomena. We have also analyzed the available interchangeability criteria and their applicability when using natural gas/hydrogen mixtures. The impact of the hydrogen content on the radiation heat transfer in the furnaces of gas equipment is described in the paper for the first time. Methods: The methodology of the paper is based on a critical analysis of available literature data on combustible gases interchangeability as well as theoretical and experimental studies performed by the authors. We have derived dependencies that allow us to determine the possibility of gas equipment transition to the combustion of natural gas/hydrogen mixtures. We have also developed recommendations on the permissible hydrogen content in a natural gas/hydrogen mixture that would ensure the efficient, safe, and green use of such fuel in domestic and commercial heating units. Results: Scientific findings and practical results of the study make it possible to implement partial gradual costeffective decarbonization in the area of gas fuel utilization as an intermediate stage of transition to more extended hydrogen combustion. PubDate: 2022-03-31 DOI: 10.23968/2500-0055-2022-7-1-33-45 Issue No:Vol. 7, No. 1 (2022)
Authors:Olga Tretiakova Pages: 46 - 55 Abstract: Introduction: In recent years, houses out of vertical squared timber have become widespread. Vertical bars make it possible to use the effective wood behavior in compression and ensure maximum strength of the material along the fibers. Vertical bars are subject to compression with bending, which can result in loss of strength and buckling in building structures. In the available research papers and technical literature, the issue of the stress-strain state of such walls has not been analyzed. The purpose of this study was to formulate a calculation method for walls out of vertical squared timber, based on the available traditional approaches to wooden structures. We propose a calculation method for walls out of vertical squared timber as a set of elements resisting compression with bending, including a check for limiting slenderness. Results: Permissible heights of walls for buildings with bays of 10 and 12 m were obtained. The results can be used in the design of low-rise residential and public buildings, mansard superstructures of multi-story buildings. PubDate: 2022-03-31 DOI: 10.23968/2500-0055-2022-7-1-46-55 Issue No:Vol. 7, No. 1 (2022)
Authors:Nguyen Quoc Toan, Nguyen Van Tam, Tran Ngoc Diep, Pham Xuan Anh Pages: 56 - 71 Abstract: Introduction: Building Information Modeling (BIM) is characterized by potential benefits at many phases of the construction project life cycle. However, no comprehensive study has been conducted to evaluate the benefits of BIM adoption and implementation for project stakeholders in the Vietnamese construction industry context. Methods: This study aimed to identify and evaluate the benefits of BIM adoption and implementation in construction projects based on the perception of project stakeholders through data collection from 159 valid construction practitioners. The reliability and validity tests were performed to analyze collected data by SPSS 22 software. Results: The results demonstrated that four primary clusters of the project stakeholders received benefits when BIM was adopted in construction projects: architectural and structural design units (10 benefits), facility management units (8 benefits), contractors (6 benefits), and owners (6 benefits). These clusters accounted for 58.954%, 5.975%, 4.682%, and 3.736%, respectively, of the variance that characterized the benefits of BIM adoption. The findings indicated that ‘improve the quality of design drawings’, and ‘minimize conflicts/changes’ were the most significant BIM benefits for architectural and structural design units, whereas ‘convenient for managing project data’ and ‘easy planning and resource mobilization’ were the top benefits for facility management units. For contractors, ‘minimize construction errors’ and ‘construction cost saving’ were the most prominent benefits. Besides, BIM brought owners such striking benefits as ‘maximize project performance’ and ‘easier to choose investment options’. PubDate: 2022-03-31 DOI: 10.23968/2500-0055-2022-7-1-56-71 Issue No:Vol. 7, No. 1 (2022)
Authors:Jan Vatulin, Denis Potakhov, Egor Potakhov, Sergei Orlov Pages: 72 - 78 Abstract: Introduction: Currently, mobile boom cranes equipped with telescopic boom equipment are widely used in construction, loading and unloading, as well as installation. Purpose of the study: We aimed to develop a dynamic model for a railway lifting crane, taking into account the interaction of its structural elements with each other and the bearing soil surface in a three-dimensional formulation. Methods: In the course of the study, we used Simulation and Motion modules of the SolidWorks software package, Klepikov’s non-linearly deformable soil model, and Lagrange’s equation of the second kind. Results: As a result, we developed a numerical analytical 3D model describing dynamic loading and deformation of the “mobile boom crane – foundation” system in a three-dimensional formulation. The model takes into account the following: the internal bending deformation and the interaction of the mating structural elements of a crane (telescopic sections, telescoping hydraulic cylinders, and outriggers), hoist rope rigidity, grillage (framework of sleepers) influence, elastic and plastic properties of the base platform soil, and action of inertial loads on the structural elements of the lifting crane. PubDate: 2022-03-31 DOI: 10.23968/2500-0055-2022-7-1-72-78 Issue No:Vol. 7, No. 1 (2022)
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