69439 2658-5553 17 2 17 2021 1-60

RAR RUS 1701-1701 0000-0003-1398-462X Moscow Power Engineering Institute Dai Qiao 228441531@qq.com

Moscow, Russian Federation

Analytical Dependence of Planar Truss Deformations on the Number of Panels The object of the study is a planar statically determinate truss of the regular type. By the method of induction, based on the results of calculations of a series of similar trusses with a consistently increasing number of panels, the desired dependence is derived. All transformations and the solution of the system of linear equations for determining the forces in the rods are performed in the Maple computer mathematics package. The deflection is calculated using the Maxwell-Mohr formula. Results. The formula for the dependence of the deflection on the number of panels contains ten coefficients obtained from the solution of recurrent equations. Graphs of the dependence of the deflection and horizontal displacement of the movable support under the action of a uniform load along the upper belt are constructed. The asymptotics of the solutions is found. 10.34910/ALF.17.1 69 Truss Deformations Deflection Shear Maple Induction https://alfabuild.spbstu.ru/article/2021.17.1/

RAR RUS 1702-1702 0000-0001-8018-8100 Zhuravov Kirill Alekseevich AAE-3259-2020 56296687300 0000-0002-2299-3096 Rybakov Vladimir Alexandrovich 56237511300 Steel Construction Development Association Nazmeeva Tatiana Vilsovna naztv@mail.ru

Moscow, Russian Federation

An Analysis of the Criteria for Evaluating the Efficiency and Optimization of Light Gauge Steel Structures. А Review Construction is one of the few areas that requires continuous production. In connection with the COVID-19 pandemic and its appearance against the background of financial instability, it is necessary to carefully study the market of building structures and materials to select the most effective and less costly technologies. The analysis of the construction industry showed that in a crisis, prefabricated buildings based on a steel frame are becoming favorites in comparison with traditional technologies. Against this background, it is important to evaluate for an objective assessment of the effectiveness. The analysis of the use of technical and economic models for assessing the effectiveness of construction. 10.34910/ALF.17.2 69 Light gauge stee Steel structures Steel construction Thin walled structures Structural analysis https://alfabuild.spbstu.ru/article/2021.17.2/ 1702_1.pdf

RAR RUS 1703-1703 0000-0002-0683-2786 Peter the Great St. Petersburg Polytechnic University Grebenyuk Egor Alexandrovich inj5@yandex.ru

St. Petersburg, Russian Federation

0000-0001-5903-289X Peter the Great St. Petersburg Polytechnic University Vysotsky Alexander Evgenievich

St. Petersburg, Russian Federation

57216911176 0000-0003-2716-979X Peter the Great St. Petersburg Polytechnic University Novik Anatoly Nikolaevich novik.anatoliy@inbox.ru

St. Petersburg, Russian Federation

0000-0001-7325-5555 Peter the Great St. Petersburg Polytechnic University Ovchinnikov Vladislav Vyacheslavovich

St. Petersburg, Russian Federation

0000-0002-5227-982X Peter the Great St. Petersburg Polytechnic University Sidelnikov Egor Romanovich

St. Petersburg, Russian Federation

Transformation of Internal CAD's 3D Coordinate System and IFC Files Coordination Combining files in shared coordinates from software's internal coordinates is a widespread problem in BIM working processes because only some programs support both coordinate types. The mathematical algorithm was proposed to prevent manual operations and increase accuracy. The algorithm's practical implementation finds transformation parameters between CAD's internal 3D-coordinate system and shares coordinates using at least 3 points in both systems use a method of square leasts. The proposed algorithm is a particular case of general geodetic Helmert transformation used in a local area without some parameters (only dX, dY, dZ and ωz are using). To check the accuracy of calculated parameters was entered a linear error that equals a returning value of square leasts’s method for most optimum decision and comparing that linear error with acceptable value in CAD systems.  By way of file converting example, a popular exchange data format in BIM projects as IFC files were considered. The program's implementation was executed in C# program language as a desktop application and class library, that will let change any IFC-files to adding the needing shared coordinates. All source code was published at GitHub https://github.com/GeorgGrebenyuk/IFC_GeoSupport. 10.34910/ALF.17.3 69 IFC coordination coordination model BIM CAD coordinate transformation Navisworks https://alfabuild.spbstu.ru/article/2021.17.3/ 1703.pdf

RAR RUS 1704-1704 H-9967-2013 16412815600 0000-0002-8588-3871 Moscow Power Engineering Institute Kirsanov Mikhail Nikolaevich mpei2004@yandex.ru

Moscow, Russian Federation

0000-0001-6122-8752 Moscow Power Engineering Institute Maslov Anton Nikolaevich maslovanton@list.ru

Moscow, Russian Federation

Estimation of the Natural Vibration Frequency of a Triangular Mast The object of research is a spatial statically determine truss with the shape of a triangular pyramid with a cross-shaped lattice. One of the three pillars of the structure is a spherical joint. The other two are a cylindrical joint and a vertical post. In the analytical form, the dependence of the first natural frequency of vibrations of the truss on its size, mass, and number of panels is found. Method. The stiffness of a truss with masses concentrated at the nodes is determined by the Maxwell-Mohr formula. The analytical estimate of the first frequency is calculated using the Dunkerley formula. The induction method is used to generalize a series of particular solutions for trusses with a consistently increasing number of panels. The general terms of the sequence of coefficients are determined from the solution of linear homogeneous recurrent equations. All transformations, including finding the forces in the rods by cutting out the nodes, are performed in the Maple computer mathematics system. Results. The frequency dependence on the number of panels for trusses with an arbitrary slope of the side faces is found in numerical form. An analytical solution can be obtained for the case of vertical faces of the structure when the truss has the shape of a regular triangular prism. A comparison of the analytical solution with the numerical one shows that the accuracy of the analytical estimate from below increases with an increase in the number of panels. 10.34910/ALF.17.4 69 Truss Maple Symbolic solution Natural oscillation frequency Mast Dunkerley estimate https://alfabuild.spbstu.ru/article/2021.17.4/ 1704.pdf

REV RUS 1705-1705 6506150284 0000-0003-1139-3164 Moscow State University of Civil Engineering Sainov Mikhail Petrovich mp_sainov@mail.ru

Moscow, Russian Federation

0000-0002-5279-9550 Moscow State University of Civil Engineering Poslykhalin Yuriy Andreevich awer1999@mail.ru

Moscow, Russian Federation

Asphalt Concrete Faces of Embankment Dams: A Review Embankment dams with asphalt concrete face have been used already 100 years; in the XX-th century, several hundreds of such embankment dams were built. However, asphalt concrete coatings were primarily used in Europe, and in other countries, including Russia, they were not widely used. For assessing advantages and disadvantages and prospects of further use of asphalt concrete face in embankment dams, the authors analyzed the development of these structures in a historical retrospective. For compiling a historical survey, there were used hard-to-get publications of the previous years. Results. The experience of the first half of the XX-th century in using bituminous materials in embankment dams showed that asphalt concrete faces showed the greatest safety and effectiveness. In the 1950-s there were developed typical reliable methods of creating asphalt concrete faces. Their implementation permitted considerably wider use of asphalt concrete faces in embankment dams. However, using asphalt concrete faces is still restricted due to the negative impact of temperature effects on asphalt concrete properties. More often, the seepage-control elements of embankment dams are made as asphalt concrete diaphragms or geo-membranes. The article gives information about cases of asphalt concrete failures; their disadvantages are analyzed and several methods of their overcoming. Conclusion. Experience in the operation of modern asphalt concrete faces evidence about the safety of these structures, but further refinement is required for widening the sphere of their use. 10.34910/ALF.17.5 69 Asphalt concrete faced dam Asphalt concrete Bituminous concrete Embankment dam https://alfabuild.spbstu.ru/article/2021.17.5/