33407 2304-6295 1 106 2023 1-60

RAR RUS 10601-10601 H-9967-2013 16412815600 0000-0002-8588-3871 National Research University Moscow Power Engineering Institute Kirsanov Mikhail Nikolaevich mpei2004@yandex.ru

Moscow, Russian Federation

Model of a hexagonal prismatic truss. Oscillation frequency spectrum The object of research is a spatial truss. A scheme of a statically determinate tower-type truss is proposed. The purpose of the study is to derive formulas for the dependences of the first frequency of natural oscillations on the dimensions of the structure and to numerically analyze the spectra of a family of regular trusses of various orders. It is assumed that the mass of the structure is concentrated in the truss nodes. Method. To determine the analytical expressions for the forces in the rods, the equilibrium equations of the nodes are compiled in matrix form using the operators of the Maple computer mathematics system. The rigidity of the structure required to calculate the vibration frequencies is calculated using the Maxwell - Mohr formula. The lower analytical estimate of the first frequency is obtained in the Dunkerley approximation by calculating the partial frequencies. Only horizontal oscillations of the weights are assumed, each weight has two degrees of freedom. Generalizing a series of solutions for trusses with a successively increasing number of panels, we obtain the dependence of the lower frequency estimate on the number of panels. Results. A formula is obtained for the first oscillation frequency as a function of the number of panels. A good agreement between the found analytical solution and the numerical solution obtained with allowance for all degrees of freedom of the structure is shown. Graphs of the dependence of the first frequency and the relative error of the analytical solution on the number of panels are plotted. With an increase in the number of panels, the error of the found solution decreases from 7% to 3%. The natural frequency spectrum of the truss is analyzed. Spectral isolines and constants are found in the frequency set of a series of regular trusses 10.4123/CUBS.106.1 69 Spatial truss Hexagonal prism Natural vibrations Lower frequency estimate Dunkerley method Induction Frequency spectrum isoline Spectral constant https://unistroy.spbstu.ru/article/2023.106.1/ 10601.pdf

RAR RUS 10602-10602 AAE-3259-2020 56296687300 0000-0002-2299-3096 Peter the Great St. Petersburg Polytechnic University Rybakov Vladimir Alexandrovich fishermanoff@mail.ru

St. Petersburg, Russian Federation

Condition Load Effect Factor of Profile Steel in Lightweight Steel Concrete Wall Panels The goal of the work is to study the nature of the behavour and determine the bearing capacity (determination of the coefficient of working conditions) of fragments of wall structures made of heat-insulating non-autoclaved monolithic foam concrete with a density of 200 kg/m3, profiled steel and fiber-cement sheets. The object of research is lightweight steel concrete structures  (LGSS).The subject of research is the bearing capacity of LSCS under the action of a vertical distributed load, applied to the "bearing" part of the wall panel. The researsh method of the condition load effect factor of LSCS is based on experimental testing LSCS for one sample; carrying out a verification calculation according to the method chosen in such a way that the results of the experiment correlate with the numerical or analytical result; further carrying out a numerical experiment for a model that is completely identical to the tested LSCS sample, but without foam concrete filling (i.e. LGSS). Results. It was shown that when comparing the experimentally obtained data on the loading capacity of the LSCS wall panel and numerical calculations of the stress-strain state of the corresponding LGSS wall panel, the displacements of the LGSS are up to 2 times greater than the displacements of the LSCS, and the stresses differ from 2 to 13 times. It is proposed when using a numerically experimental method for determining the condition load effect factor of profiled steel in LSCS to perform engineering calculations of LSC-wall panels using foam concrete with density 200 kg/m3, by analogy with the calculation of light steel-concrete slabs, it is advisable to take a factor 1.25 or carry out a full series tests. 10.4123/CUBS.106.2 69 Lightweight steel concrete structures (LSCS) Wall panels Load-bearing capacity Profile steel Condition load effect factor Foam Concrete https://unistroy.spbstu.ru/article/2023.106.2/ 10602.pdf

RAR RUS 10603-10603 Dang Thu Thao dangthuthao@gmail.com ABD-2048-2021 57205074229 0000-0003-3154-8207 Peter the Great St. Petersburg Polytechnic University Sabri Mohanad Muayad Sabri mohanad.m.sabri@gmail.com

St. Petersburg, Russian Federation

Togo Issa issatogo@mail.ru Frolova Irina Evgenievna iegucova@mail.ru Basal heave stability assessment of retaining structures in cramped construction conditions: A calculation method The article is dedicated to developing a calculation method for assessing the basal heave stability of retaining structures, which considers the boundary conditions at the extreme points of the shear surface profile and satisfies all three equilibrium equations. The object of research is a two-row sheet pile retaining wall under conditions of water filtration into the enclosing foundation. The immersion depth of sheet piles is determined by the condition of stability of the lintel according to the scheme of deep shear, as well as the condition of suffusion strength of the soil of the base. The form of the failure surface function and the stress function on the failure surface are described by degree dependencies to consider boundary conditions at the extreme points of the shear surface to satisfy Mohr's strength theory. The stability factor is obtained by solving a system of three equilibrium equations, considering the boundary conditions at the points of intersection of the shear surface profile with the profile of the base soil mass. The calculation with different variants of the interlock permeability of the top sheet pile wall shows that the sealing of the interlocks increases the stability of the retaining structures. 10.4123/CUBS.106.3 69 Retaining structures Sheet pile wall Soil pressures Stability assessment Basal heave Equilibrium conditions Boundary conditions https://unistroy.spbstu.ru/article/2023.106.3/ 10603.pdf

RAR RUS 10604-10604 H-9967-2013 16412815600 0000-0002-8588-3871 National Research University Moscow Power Engineering Institute Kirsanov Mikhail Nikolaevich mpei2004@yandex.ru

Moscow, Russian Federation

0000-0002-6848-0974 Moscow Power Engineering Institute Luong Cong Luan luongcongluan96@gmail.com

Moscow, Russian Federation

Natural frequency spectra of spatial structure The object of the study is a diagram of a statically determinate truss in the form of a closed rectangle with vertical supporting columns along the inner contour. The structure is formed from quadrangular rod pyramids. All pyramids are united along the vertices by a square contour. Four additional horizontal ties are located at the corners of the structure. Method. Estimates of the lowest oscillation frequency of the truss are found using the Rayleigh energy method and the Dunkerley method. All mathematical transformations are performed in the Maple symbolic mathematics system. The dependence of the solution on the number of panels is obtained by generalizing a series of solutions for farms with a successively increasing number of panels. Results. The value of the first natural frequency is compared with the numerical solution obtained by analyzing the entire spectrum of natural frequencies of the vertical oscillations of the system of masses located in the truss nodes. The frequency equation is compiled and solved using the eigenvalue search operators in the Maple system. The spectrum of natural frequencies of a family of regular trusses of various orders is analyzed. 10.4123/CUBS.106.4 69 Pyramids Truss Induction Maple Natural frequency Rayleigh method Dunkerley method Spectra of natural frequencies https://unistroy.spbstu.ru/article/2023.106.4/ 10604.pdf

RAR RUS 10605-10605 Mushchanov Vladimir Filippovich mutshanov_vf@spbstu.ru Orzhehovsky Anatoly Nikolayevich Numerical methods in assessing the reliability of spatial metal structures with a high level of responsibility The object of research is methods for determining reliability indicators, as well as methods for analyzing the propensity to develop progressive destruction in steel rod structures of increased responsibility that are many times statically indeterminate. The current state of the regulatory framework in the field of ensuring the reliability of building constructions is analyzed. The current regulatory framework in the field of preventing the development of progressive collapse of constructions is analyzed. Ambiguities in determining reliability indicators in difficult spatial constructions are noted. The question of a reasonable choice of a construction element, the destruction of which can cause the process of progressive collapse, is considered. The authors note the need to develop a clear methodology for determining the reliability characteristics of spatial many times statically indeterminate rod constructions of increased responsibility. Method. Based on the finite element method in a geometrically and structurally nonlinear formulation, an algorithm for determining the totality of key construction elements has been developed. The main purpose of the algorithm is the ability to analyze the propensity of the studied construction to progressive collapse based on the identification of stabilization states and subsequent calculation of its reliability indicators using a model of parallel connection of elements. Results. The article proposes a new method for the reasonable selection of a set of key most critical elements of spatial steel rod constructions. The use of this technique makes it possible to simplify and concretize the calculation of the construction for the tendency to progressive collapse. A method for determining the reliability indicators of spatial rod constructions of an increased degree of responsibility is proposed. The authors propose a methodology for determining the reliability indicators of spatial core constructions of an increased degree of responsibility. An algorithm for calculating reliability indicators of the constructions under consideration has been developed in the MATLAB programming language. The proposed methodologies have been tested on the example of a structural coating. The construction is square in plan and has a side length of 24 m. The cell of the core plate is made in the form of a pentahedron with a height of 3 m. A demonstration engineering calculation of the construction under consideration has been performed. According to the calculation results, the tendency to progressive destruction has been eliminated in the construction. The security characteristic increased from -1.54 to 2.67. This indicates an increase in the level of reliability of the core slab. 10.4123/CUBS.106.5 69 Progressive collapse; Reliability; Metal structures Finite element method; Structurally and geometrically nonlinear calculation; Failure probability https://unistroy.spbstu.ru/article/2023.106.5/ 10605.pdf

RAR RUS 10606-10606 Sergeev Vitaly Vladimirovich G-2929-2018 56227381900 0000-0003-2673-4566 Peter the Great St. Petersburg Polytechnic University Sergeeva (Nemova) Darya Viktorovna darya0690@mail.ru

St. Petersburg, Russian Federation

0000-0002-0489-4107 Gorshkov Rostislav Alexandrovich rostalsgor@gmail.com Voilokov Ilya Anatolievich Ice formation of the building with a residential pitched roof and a cold attic space at the cold climate in the millionplus city Ice on the pitched roofs threatens pedestrians and vehicles parked near buildings. This article describes the scheme of ice formation on the roofs of buildings with a pitched roof and a cold attic. To determine the conditions for the ice formation in the building a mathematical model and an equation of the thermal balance of an unheated attic room are developed. A set of measures to normalize the temperature and humidity regime in an unheated attic is developed. The dependences of the air temperature in the attic on the outside air temperature before and after the implementation of the proposed set of measures to normalize the temperature and humidity regime are defined. The developed set of measures reduce the thermal energy consumption during the heating period due to an increase in the level of thermal insulation of enclosing structures separating the cold attic from heated rooms, as well as to improve the microclimate parameters on the upper floors of operated buildings. Unlike active protection methods (usually implemented in the form of heating cables, films, and mats), the proposed complex of passive engineering and technical solutions that do not require energy resources during operation can be defined as energy saving and sustainable. The results obtained will be applicable to buildings located in the cold climate zone (D – cold climate according to the international Köppen Climate Classification). 10.4123/CUBS.106.6 69 Сold attics Roof space Building enclosure Energy efficiency Roof sheathing temperature Ice dam https://unistroy.spbstu.ru/article/2023.106.6/ 10606.pdf

RAR RUS 10607-10607 0000-0003-0827-6303 Kazan State University of Architecture and Engineering Lavrov Dmitry Igorevich 57210972600 0000-0001-6472-9413 Kazan State University of Architecture and Engineering (KSUAE) Shmelev Gennady Nikolaevich gn.shmelev@mail.ru

Russian Federation, Tatarstan republic, Kazan, Zelenaya Str., 1

0000-0001-6750-4172 Antonov Anatoliy Sergeevich antonov01234@mail.ru Translucent elements as structural part of facade systems The objects of research are translucent elements in curtain wall systems, which are common modern architectural and structural solutions. Method. To determine the stress-strain state of a translucent element as part of curtain wall systems, different calculation methods are applied to calculate insulating glass units under full wind load. These methods are based on recommendations from regulatory documents, Navier Solution and numerical experiments in Mepla ISO program and ANSYS software package. In calculations, insulating glass units have different values of linear dimensions, glass thickness and air gaps. The deformation characteristics of a two-component sealant are determined by testing the material in an experimental setup. Results. Based on the results of the work, the convergence of the methods with each other is considered, and the glass unit with the smallest deformation values in the outer glass from the action of wind loads is determined. 10.4123/CUBS.106.7 69 Hinged facade systems Translucent elements Design model Experiment Stress Deformation https://unistroy.spbstu.ru/article/2023.106.7/ 10607.pdf