33407
2304-6295
Construction of Unique Buildings and Structures
1
94
2021
1-104
RAR
RUS
9401-9401
0000-0003-4394-0791
Kirik
Ekaterina Sergeevna
Institute of Computational Modelling of the Siberian Branch of the RAS
kirik@icm.krasn.ru
Krasnoyarsk, Russian Federation
0000-0003-2149-3783
Vitova
Tatiana Bronislavovna
ICM SB RAS
Krasnoyarsk, Russian Federation
0000-0001-5669-1574
Malyshev
Andrei Valerievich
ICM SB RAS
Krasnoyarsk, Russian Federation
0000-0003-3934-126X
Popel
Egor Viktorovich
ICM SB RAS
Krasnoyarsk, Russian Federation
0000-0002-4764-3842
Kharlamov
Egor Borisovich
IT SB RAS
Novosibirsk, Russian Federation
0000-0003-4280-7796
Moiseichenko
Viacheslav Aleksandrovich
ICM SB RAS
Krasnoyarsk, Russian Federation
0000-0002-2159-3939
Kalinin
Egor Sergeevich
ICM SB RAS
Krasnoyarsk, Russian Federation
0000-0003-3660-444X
Smirnov
Nikolai Vasilevich
FGBU VNIIPO of EMERCOM of Russia
Balashikha, Russian Federation
Computer Simulation of Pedestrian Dynamics in the Design and Operation of Stadiums
The object of research is the safety and comfort of spectators while moving in stadiums and the adjacent territory. This work aims to show how using computer simulation helps analyze the influence of different conditions and check the stadium’s environment from people's comfort and safety points of view. Method. Computer simulation of pedestrian dynamics and analysis of results are applied. Results. Several arenas were considered. The influence of client groups, the layout of the stadium, and the adjacent territory, including landscape features, temporary infrastructure, were studied. Areas of high density (or congestions) were found where a potential threat to people in the case of maximum loading of the stadiums is concentrated. Ways to avoid threats were suggested and checked using computer simulation of people's movement.
10.4123/CUBS.94.1
69
Stadiums
Pedestrian Safety
Computer Simulation
Autonomous agents
Simulation platform
https://unistroy.spbstu.ru/article/2021.95.1/
9401-1.pdf
RAR
RUS
9402-9402
H-9967-2013
16412815600
0000-0002-8588-3871
Kirsanov
Mikhail Nikolaevich
National Research University Moscow Power Engineering Institute
mpei2004@yandex.ru
Moscow, Russian Federation
0000-0002-5220-1264
Vorobev
Oleg Vladimirovich
Moscow Power Engineering Institute
olvarg@mail.ru
Moscow, Russian Federation
Calculating of a spatial cantilever truss natural vibration frequency with an arbitrary number of panels: analytical solution
The research object was a spatial cantilever statically determinate truss composed of three planar trusses with a triangular lattice. The spectrum of natural frequencies of the structure was analyzed. The same concentrated masses model the inertial properties of the truss at the nodes. The task was to obtain an analytical dependence of the lowest vibration frequency of a truss on the number of panels, mass, linear dimensions of the structure, and material properties. Method. The induction method and the Maple computer mathematics system operators were used to determine the forces in the rods and generalize the result to an arbitrary number of panels. The problem was solved using the Dunkerley approach, which gives a lower frequency estimate. Maxwell-Mohr's formula determines the rigidity of the structure. Homogeneous linear recurrent equations were compiled and solved to find the common members of the sequences of coefficients in the formula for the frequency. Results. The accuracy of the formula obtained by the Dunkerley method was estimated from comparison with a numerical calculation of the entire spectrum of natural frequencies. The comparison shows the good accuracy of the derived formula. As the number of panels increases, the accuracy of the lower estimate increases too. The same frequency for all trusses was found in the spectra of trusses with a different number of panels. This frequency is the spectral constant and depends only on the size of the system, the stiffness of the members, and the mass. The existence of spectral isolines with the property of asymptotically tending to a certain constant value was shown.
10.4123/CUBS.94.2
69
Truss
Vibration
Dunkerley method
Spectral constant
Spectral isolines
Symbolic solution
Natural frequencies
https://unistroy.spbstu.ru/article/2021.95.2/
RAR
RUS
9403-9403
H-9967-2013
16412815600
0000-0002-8588-3871
Kirsanov
Mikhail Nikolaevich
National Research University Moscow Power Engineering Institute
mpei2004@yandex.ru
Moscow, Russian Federation
0000-0002-1184-3922
Petrichenko
Elizaveta Alexandrovna
Moscow Power Engineering Institute
Moscow, Russian Federation
0000-0002-5220-1264
Vorobev
Oleg Vladimirovich
Moscow Power Engineering Institute
olvarg@mail.ru
Moscow, Russian Federation
The formula for the lower estimate of the fundamental frequency of natural vibrations of a truss with an arbitrary number of panels
The object of the research is a planar, statically determinate girder of the beam type with a triple diagonal lattice.The truss mass is modeled by equal masses distributed over the nodes of the lower chord. By the Dunkerley method, under the assumption of vertical vibrations of loads, a lower analytical estimate of the first natural vibration frequency is obtained. Method. The forces in the members are calculated by cutting out nodes from the solution of a system of linear algebraic equations. Generalization of individual solutions to the case of an arbitrary number of panels is carried out by the induction method with the involvement of operators of the Maple computer mathematics system. Results. Comparison with the numerical solution found from the solution on the spectrum of natural vibrations of a multi-mass system shows that the estimation accuracy depends on the number of panels and varies from 16% for trusses with two panels to 4% for trusses with more than 11 panels. With a decrease in the ratio of the panel height to its length, the accuracy slightly increases. Based on the analysis of the derived formula, it is shown that the dependence of the first frequency on the height of the truss has a maximum. An algorithm for generalizing the solution to the case of members of different stiffness is proposed.
10.4123/CUBS.94.3
69
Truss
Natural vibrations
Lower frequency estimate
Dunkerley 's method
Maple
Induction
https://unistroy.spbstu.ru/article/2021.95.3/
RAR
RUS
9404-9404
57194452261
0000-0003-2062-5289
Mukhametrakhimov
Rustem Khanifovich
Kazan State University of Architecture and Engineering
Kazan, Russian Federation
57194444416
0000-0003-0090-2410
Lukmanova
Liliya Valievna
Kazan State University of Architecture and Engineering
Kazan, Russian Federation
Influence Of Cement-Sand Mortar Mobility On The Quality Of 3D Printed Hardened Composite
Introduction. The main requirement of formability in the 3D concrete printing (3DCP), in contrast to the classical technology of concrete, is the dimensional stability of freshly laid layers. The dimensional stability is expressed in maintaining the geometric dimensions of the molded element, solidity, uniformity, and position in space under the influence of technological and operational factors, and determines the quality of construction products. The influence of the unmodified cement-sand mortar mobility on the quality of 3D printed hardened composites based on them has been studied. Materials and methods. The mortar mobility was determined following Russian State Standard GOST 5802-86. The samples were molded by layer-by-layer extrusion on a construction 3D printer "AMT S-6044" ("SPETSAVIA LLC", Yaroslavl, Russia). Determination of defects of cement-sand mortar mixture and hardened composites was carried out by visual instrumental method. Structure kinetics of the mortar mix was determined to ASTM C403 using a pocket penetrometer C194. Results. It was revealed that 3D printing on the investigated 3D printer is possible on cement-sand mortar mixtures of mobility classes from Pk 2 to Pk 4; however, the products have defects and damage, their appearance and nature are very different. The 3D printed mortar mobility has a significant effect on the structure kinetics and the deviation of geometric parameters. The expediency of using the penetrometric method in the study of the formation of the plastic strength of the printed mixture both in the coagulation and in the initial crystallization period is shown, which is effective in predicting the ability of the mixture to hold the formed layers without deforming the previous ones. It has been established that there are no optimal compositions of a cement-sand mortar mixture with a certain mobility class, which simultaneously meets all the requirements of the considered quality indicators of hardened composites. Conclusions. It was shown the need to apply such an approach to modifying the compositions of raw mixtures for 3D concrete printing, in which, first of all, their optimal rheological and technological properties will be achieved, ensuring high quality of molded composites increases.
10.4123/CUBS.94.4
69
Concretes
Cements
Mortars
3D Printing
3DCP
Extrusion
Additive manufacturing
Mobility
Rheology
https://unistroy.spbstu.ru/article/2021.95.4/
9404.pdf
RAR
RUS
9405-9405
7004191121
0000-0003-0473-0302
Pasternak
Hartmut
Brandenburg University of Technology
h.pasternak@web.de
Cottbus, Germany
0000-0002-1570-6298
Shoushtarian Mofrad
Ashkan
Brandenburg University of Technology
ashkan.shoushtarianmofrad@b-tu.de
Cottbus, Germany
Numerical and Analytical Study on Bending Stiffness of Sandwich Panels at Ambient and Elevated Temperatures
This paper presents an investigation on the bending stiffness of sandwich panels at ambient and elevated temperatures. A finite element (FE) model is developed to verify simulations with experimental
results, and then a parametric study at different temperatures is carried out. After that, an analytical study to determine the bending stiffness at room temperatures according to the current specification is
conducted. Furthermore, the analytical solutions are developed to use at elevated temperatures. The objective of the current research is to compare the numerical and analytical results. It is observed that analytical solutions developed to evaluate the bending stiffness at elevated temperatures are conservative and reliable.
10.4123/CUBS.94.5
69
Sandwich panels
Bending stiffness
Analytical study
Finite element analysis
Parametric study
Elevated temperatures
https://unistroy.spbstu.ru/article/2021.95.5/
RAR
RUS
9406-9406
0000-0001-7444-6345
Shokin
Aleksei Aleksandrovich
Saint Petersburg Mining University
alex.95.sh@yandex.ru
St. Petersburg, Russian Federation
0000-0002-9144-1412
Semenov
Daniil Arkadievich
Peter the Great St. Petersburg Polytechnic University
dan290797@gmail.com
St. Petersburg, Russian Federation
Frequency-Dependent Dynamic Characteristics of the Soil Foundation
.The object of the research is the dynamic characteristics of the soil foundation used for calculating structures for seismic loads. The purpose of this work is a comparative analysis of dynamic characteristics for different types of soils. The impact of the embedment of the foundation is also assessed. The article compares the normative and finite element methods of calculation. Method. The dynamic characteristics are determined from the solving of the task of harmonic vibrations of a stamp on an elastic half-space. The finite element model was verified using an analytical solution. To simulate an infinite region in the limited volume of soil, elements that absorb the energy of vibrations (Perfectly Matched Layer) were used. Results. Verification of the finite element model showed an acceptable error with an analytical solution. By solving a number of problems, it was found that the normative formulas for calculating dynamic characteristics give correct values only for low-frequency effects. Comparison graphs show a sharp increase in the frequency dependence of characteristics when soil conditions degrade (the shear wave velocity decreases).
10.4123/CUBS.94.6
69
Soil-structure interaction
Frequency domain
Dynamic response
Earthquake engineering
Foundation vibration
Soil Dynamic
Perfectly matched layers
https://unistroy.spbstu.ru/article/2021.95.6/
9406.pdf
RAR
RUS
9407-9407
7801461898
0000-0002-8616-9717
Mirzaev
Ibrakhim
Institute of Mechanics and Seismic Stability of Structures named after M.T. Urazbaev
ibrakhim.mir@mail.ru
Tashkent, Uzbekistan
0000-0002-2499-0243
Turdiev
Malikjon Sayfiddin o’g’li
Tashkent State Transport University
Tashkent, Uzbekistan
Vibrations of Buildings with Sliding Foundations under Real Seismic Effects
The research object was the vibrations of buildings on sliding foundations with dry friction under the action of real earthquakes. Methods. The samples of a four-story and a nine-story building were used with a set of five earthquake records of 7-10 MSK-64 scale. The design model of the building has the form of a system with many degrees of freedom, subjected to shear vibrations only. The Coulomb dry friction model describes the foundation-grillage interaction. The foundation motion is specified as the horizontal component of the seismogram of a real earthquake. The absence of a condition to calculate the friction force between two absolutely rigid bodies during the period of their cohesion in the dynamics does not allow determining the time of the beginning of sliding, and this complicates the problem. In addition, the seismograms of real earthquakes are of complex nature, which can lead to multiple changes in the state of sliding and cohesion between the grillage and the foundation. Discretization of the problem in time and the use of a logical algorithm made it possible to solve this problem. The implicit Newmark scheme was used; at each time step, the problem was solved in three statements and the true solution was chosen. To ensure the required accuracy of solving the nonlinear problem, the time step value was selected by performing a computational experiment. Results. The developed algorithm for calculating displacements, velocities, accelerations, and shear forces was proposed based on the horizontal component of the seismogram record. The results obtained are presented in the form of comparative graphs of the grillage and foundation displacements, and the shear force of the first floor. The results were also presented in ten tables for four-story and nine-story buildings subjected to the influence of five earthquakes. These tables show the maximum values of the shear forces for the floors of the buildings. With a favorable combination of the dynamic characteristics of the building and the amplitude-frequency response of the seismogram, the use of a sliding foundation can lead to multiple reductions in the shear force in the building, while a poor combination of them in a sliding foundation gives an insignificant effect. It is shown that a sliding foundation does not always lead to multiple reductions in shear force.
10.4123/CUBS.94.7
69
Seismic waves
Building dynamics
Seismic isolation
Fluor plastic
Dry friction
https://unistroy.spbstu.ru/article/2021.95.7/
9407.pdf