75504
2712-8172
Magazine of Civil Engineering
3
119
2023
1-127
RAR
RUS
11901-11901
0000-0002-6586-530X
Northeast Forestry University
Zhang
Maohua
zmh7716@163.com
Harbin, China
0000-0003-4814-070X
Northeast Forestry University
Ma
Danan
mn2617@nefu.edu.cn
Harbin, China
0000-0002-9132-0039
Harbin Institute of Petroleum
He
Jia
461104630@qq.com
Harbin, China
0000-0002-0017-2078
Northeast Forestry University
Han
Yue
767147252@qq.com
Harbin, China
Sulfate corrosion resistance of foundation concrete with nano-particles
With the rapid development of modern industry, the foundation soil and the underground water in some areas are severely polluted by the corrosive medium affecting the durability of foundation concrete. Sulfate corrosion is one of the major factors leading to the destruction of foundation concrete. The sulfate corrosion resistance of foundation concrete with nano-particles (nano-SiO2 and nano-CaCO3) under the action of dry-wet cycle is experimentally studied, and compared with that of plain foundation concrete. The test results indicate that, under the action of dry-wet cycle, the sulfate corrosion resistance of foundation concrete is significantly improved with the addition of nano-particles. With the increasing content of nano-particles, the sulfate corrosion resistance of foundation concrete gradually rises to its peak and then drops step by step. The sulfate corrosion resistance of foundation concrete with nano-SiO2 is superior to that of foundation concrete with the same amount of nano-CaCO3. When the content of nano-SiO2 and nano-CaCO3 is respectively 2.0 % and 1.0 % by weight of binder, the sulfate corrosion resistance of foundation concrete is the best. Because the pore structure of concrete is improved with the addition of nano-particles, as nano-SiO2 can react with Ca(OH)2 and nano-CaCO3 can react with C3A, nano-particles can significantly enhance the sulfate corrosion resistance of foundation concrete.
10.34910/MCE.119.1
624
concrete
foundation
nanoparticles
sulfate
corrosion
dry-wet cycles
https://engstroy.spbstu.ru/article/2023.119.1/
RAR
RUS
11902-11902
Research Institute for the Development of Digital Technologies and Artificial Intelligence
Ravshanov
Normahmad
ravshanxade-09@mail.ru
Tashkent, Uzbekistan
57209309390
0000-0003-1351-7861
Tashkent Institute of Irrigation and Agricultural Mechanization Engineers
Abdullaev
Zafar
abdullaevv.zafar@gmail.com
Tashkent, Uzbekistan
Peter the Great St. Petersburg Polytechnic University
Kotov
Evgeny
ekotov.cfd@gmail.com
St. Petersburg, Russia
0000-0003-0521-6882
Tashkent Institute of Irrigation and Agricultural Mechanization Engineers
Turkmanova
Shodiya
turkmanovashodiya@gmail.com
Tashkent, Uzbekistan
Numerical study of the process of unsteady flow in a three-layer porous medium
The unsteady fluid flow in a three-layer porous medium is numerically investigated and is an important and topical problem. An analytical solution of the equation for the pressure fluid layer is obtained on the basis of the theory of elastic regime, taking into account the overflow from the coating and the low-permeability layer into the low-permeability bulkhead and external sources that greatly affect the liquid level change. In the main bounded aquifer only horizontal liquid migrations prevail, and in the cover and low-conductive layers only vertical migrations prevail, allowing for horizontal components of the flow rate to be omitted here. Evaporation from the surface of a liquid in a porous medium is considered. Evaporation from the surface of a liquid in a porous medium significantly affects the distribution of overflows in the layers and the distribution of the liquid level in a porous medium. Therefore, when designing vertical drains for enhanced oil recovery in multilayer reservoirs and designing fluid flows in reservoirs, evaporation must be taken into account. The computational experiments have established that the dynamics of changes in the liquid level in a porous medium depends significantly on the evaporation parameter. With an increase in its value, the liquid level in a porous medium decreases proportionally over time. The accuracy of the numerical solution using the balance equation showed that the error does not exceed 1.3%.
10.34910/MCE.119.2
66.067.1
mathematical model
groundwater
groundwater
filtration
analytical solution
numerical algorithm
https://engstroy.spbstu.ru/article/2023.119.2/
RAR
RUS
11903-11903
H-9967-2013
16412815600
0000-0002-8588-3871
National Research University "Moscow Power Engineering Institute"
Kirsanov
Mikhail
mpei2004@yandex.ru
14, Krasnokazarmennaya, 111250 Moscow, Russia
Hexagonal rod pyramid: deformations and natural oscillation frequency
A new scheme of a statically determinate dome truss is proposed. The purpose of the study is to obtain exact formulas for structural deflections under a uniform load and to find upper and lower analytical estimates of the first frequency of natural oscillations depending on the number of panels, sizes, and masses concentrated in the truss nodes. Calculation of forces in the truss rods is performed by cutting nodes. The system of equations in projections on the coordinate axes, compiled in the Maple software, includes the forces in the rods and the reactions of vertical supports located along two contours of the structure at the base. The amount of deflection and stiffness of the entire truss is calculated using the Mohr integral. To determine the lower estimate of the first frequency an approximate Dunkerley method is used. The formula for the upper limit of the first frequency is derived by the Rayleigh energy method. In the Rayleigh method, the shape of the deflection from the action of a uniformly distributed load is taken as the deflection of the truss. Displacements of loads are assumed to be only vertical. The overall dependence of the solution on the number of panels is obtained by induction on a series of solutions for trusses with a successively increasing number of panels. The operators of the Maple system of symbolic mathematics are used. Based on the calculation results, it was concluded that the distribution of forces over the structure rods does not depend on the number of panels. Asymptotes were found on the graphs of the obtained analytical dependences of the deflection on the number of panels for different truss heights. The estimates of the first natural frequency are compared with the numerical solution obtained from the analysis of the natural frequency spectrum. The coefficients of the frequency equation are found using the eigenvalue search operators in the Maple system. It is shown that the lower analytical estimate based on the calculation of partial frequencies differs from the numerical solution by no more than 54 %, and the upper estimate by the Rayleigh method has an error of about 2 %. The formula for the lower Dunkerley frequency estimate is simpler than the Rayleigh estimate.
10.34910/MCE.119.3
624.35:531.391.3
spatial truss
hexagonal dome
natural vibrations
lower frequency bound
upper frequency bound
Dunkerley method
Rayleigh method
Maple
induction
https://engstroy.spbstu.ru/article/2023.119.3/
UNK
RUS
11904-11904
57208305419
0000-0002-8950-7558
Northern (Arctic) Federal University named after M.V. Lomonosov
Popov
Egor
EPV1989@yandex.ru
Arkhangelsk, Russia
Northern (Arctic) Federal University named after M.V. Lomonosov
Labudin
Boris
labudin@hotmail.ru
0000-0003-2810-6336
Northern (Arctic) Federal University named after M.V. Lomonosov
Konovalov
A.Yu.
a.konovalov@narfu.ru
Arkhangelsk, Russia
Northern (Arctic) Federal University named after M.V. Lomonosov
Karelskiy
Aleksandr
kaw_79@mail.ru
0000-0002-1236-5950
Northeast Forestry University
Sopilov
Valerii
sopilov.v@edu.narfu.ru
Arkhangelsk, Russia
0000-0002-1216-7567
Northern (Arctic) Federal University named after M.V. Lomonosov
Bobyleva
Aleksandra
aleksandra-bobyleva@mail.ru
Arkhangelsk, Russia
57208307525
0000-0003-0153-8729
Northern (Arctic) Federal University named after M.V. Lomonosov
Stolypin
Denis
Stolypin.Denis.A@yandex.ru
Arkhangelsk, Russia
Numerical buckling calculation method for composite rods with semi-rigid ties
Research object: composite centrally-compressed structures with semi-rigid nonlinearly deformable connections, which are put into operation at the very beginning of loading the element. Research goal: development of a numerical method for calculating the strength and stability of compressed composite rods, which takes into account the nonlinear deformation of shear bonds, the shear stiffness coefficient of which has the form of a functional dependence and is equal to the angle of inclination of the tangent drawn to the experimental load–strain curve (T–δ) at the point with a given shear force T. Methods: the method of solving the problem consists in dividing the component element into separate sections, compiling a system of equations describing the increment of contiguous fibers in the shear seams. The load is applied in steps, after the next step the total shear forces in the bonds are determined and the stiffness coefficients for the next calculation step are clarified; at each step, the system is “probing” for the possibility of loss of stability. The resulting value of the critical force is compared with the sum of all load steps applied at this stage of the calculation, the calculation stops when the specified calculation accuracy is reached. If necessary, to obtain the resulting values, the received forces in the bonds and the normal stresses in the branches of the component structure are summed up. Results: the calculation of a three-layer timber pillar is presented. The pillar is reinforced with side overlays fastened using nonlinear-compliant shear bonds. The results of linear and nonlinear calculations are compared for different values of the stiffness coefficient of the bonds. The possible calculation error with the normative value of the stiffness coefficient is established.
10.34910/MCE.119.4
624.046.3
composite structures
semi-rigid connections
buckling
numerical methods
nonlinear analysis
experimental study
shear stiffness
https://engstroy.spbstu.ru/article/2023.119.4/
RAR
RUS
11905-11905
0000-0002-0126-2446
State Key Laboratory of Mining Response and Disaster Prevention and Control in Deep Coal Mines, Anhui University of Science and Technology
Yang
Rong-Zhou
Rongzhouy@outlook.com
Huainan, China
0000-0001-8438-3130
State Key Laboratory of Mining Response and Disaster Prevention and Control in Deep Coal Mines, Anhui University of Science and Technology
Xu
Ying
yxu@aust.edu.cn
Huainan, China
0000-0002-5538-617X
School of Civil Engineering and Architecture, Anhui University of Science and Technology
Chen
Pei-Yuan
peiyuan29@126.com
Huainan, China
Dynamic response characteristics of CFRP/steel-cylinder confined rubber cement mortar based on cyclic impact loading
Rubber cement-based material is one of the important ways of utilizing waste rubber. Fatigue failure and impact failure are the most common failure forms of concrete structures, but the low stiffness and low strength of rubber cement-based materials do no allow them to be used in the main bearing structure. Therefore, the use of appropriate reinforcement materials and technical methods to effectively improve the yield stiffness, bearing capacity, ductility, and energy dissipation capacity of rubber cement-based materials can not be ignored. To explore the dynamic response characteristics of rubber cement mortar (RCM) with different confine conditions, the split Hopkinson pressure bar (SHPB) cyclic impact tests of four kinds of confined RCM were carried out. Firstly, the four different confine modes of RCM were designed by using the carbon fiber reinforced polymer (CFRP) sheet and steel cylinder. Then, the SHPB test system was used to carry out the amplitude-enhanced cyclic impact tests of RCM with different confine modes. Lastly, the dynamic mechanical behavior, energy behavior, dynamic damage, and failure modes of RCM with different confine modes were compared and analysed. The results show that the end faces and side of RCM were confined effectively by using the CFRP sheet and steel cylinder, which strengthened the structural resistance of RCM. However, with the simultaneous increase in impact load and impact times, stiffness degradation still occurred due to the cumulative effect of fatigue damage. The end friction constraint of the CFRP sheet and the passive confining pressure constraint of the CFRP sheet/steel cylinder significantly improved the energy dissipation capacity and impact resistance of RCM, controlled and delayed the transverse expansion deformation and crack development of RCM, and ensured the minimum damage of RCM structure. The purpose of this paper is to provide a reference for further promoting the resource utilization of waste rubber and the practical engineering application of rubber cement-based materials.
10.34910/MCE.119.5
691
cyclic loads
rubber
mechanical properties
stress-strain curves
strain rate
energy absorption
cracks
https://engstroy.spbstu.ru/article/2023.119.5/
RAR
RUS
11906-11906
Donbas National Academy of Civil Engineering and Architecture
Tsepliaev
Maxim
m.s.sepliaev@donnasa.ru
Donbas National Academy of Civil Engineering and Architecture
Mushchanov
Volodymyr
volodymyr.mushchanov@mail.ru
Donbas National Academy of Civil Engineering and Architecture
Zubenko
Hanna
zubienko_anna@mail.ru
Donbas National Academy of Civil Engineering and Architecture
Mushchanov
Alexander
a.v.mushchanov@donnasa.ru
Donbas National Academy of Civil Engineering and Architecture
Orzhekhovskii
Anatoly
aorzhehovskiy@bk.ru
Tank shell stability: refined design schemes
In many ways, the reliability of vertical cylindrical tanks is determined by the resistance to buckling of the wall. In the current work, a variant of a detailed design scheme is considered, taking into account the presence of a spiral technological staircase for servicing the tank roof. The possibility of using the specified structural element as an external reinforcement to increase stability is analyzed. Finite element models of tanks with volumes of 10..30 thousand m3 were developed. The models took into account the actual distribution of the wind flow for tanks with a circular staircase. Using a multifactorial experiment, an analysis of the stability and stress state of the tank wall was carried out. The variable parameters were: the design solution of the stairs, the dimensions of the tanks and the load. Corresponding graphs and diagrams were constructed. As a result, the design solution and the recommended angle of inclination of the spiral staircase in the range of 30–40° were substantiated. The application of the obtained solutions improved the stability in the annular direction by up to 13 % compared to standard solutions. Wall displacements from wind load are reduced by 14 %, in turn, local stresses in the ladder attachment areas increased by no more than 5 %. In general, the inclusion of spiral staircases significantly increases the stability of the tank wall and can be considered as a good alternative to standard reinforcement methods.
10.34910/MCE.119.6
624.042.41:624.95
structural stability
storage tank
stress-strain state
finite element method
cylindrical shell
wind
aerodynamic coefficients
staircase
https://engstroy.spbstu.ru/article/2023.119.6/
RAR
RUS
11907-11907
57078866100
0000-0001-6065-678X
Vladimir State University named after Alexander and Nikolay Stoletovs
Lukina
Anastasiya
pismo33@yandex.ru
Vladimir, Russia
Vladimir State University named after Alexander and Nikolay Stoletovs
Lisyatnikov
Mikhail
mlisyatnikov@mail.ru
Vladimir State University named after Alexander and Nikolay Stoletovs
Lukin
Mikhail
lukin_mihail_22@mail.ru
M-6585-2013
6508103761
0000-0002-1196-8004
Peter the Great Saint Petersburg Polytechnic University
Vatin
Nikolai
vatin@mail.ru
Polytechnicheskay, 29
Vladimir State University named after Alexander and Nikolay Stoletovs
Roshchina
Svetlana
rsi3@mail.ru
Strength properties of raw wood after a wildfire
Using fire-damaged wood is one of the efficient and resource-saving approaches to forest conservation. The object of the study is raw wood exposed to fire. The aim of the study is to analyze the mechanical properties of fire-damaged pinewood, the height of the trunk, and determine the possibility of its use as a structural material. Tests were carried out for static bending, compression along the fibers, and tension along the fibers. We performed the tests on samples taken from the lower, middle, and upper parts of the fired wood and compared them with wood that was not exposed to fire. It was established that during a ground and medium fire, the strength properties of wood are most reduced in the apical part of the trunk by 41.80 % compared to wood undamaged by fire. The smallest decrease in strength occurred in the lower part of the tree. It was determined that with sufficiently small damage to wood by fire, i.e., a decrease in the cross-sectional area to 15 %, it can be partially used as a structural material.
10.34910/MCE.119.7
691.11
wood
wildfire
strength
weakened wood
residual resource
resource-saving
https://engstroy.spbstu.ru/article/2023.119.7/
RAR
RUS
11909-11909
0000-0003-2372-6544
Kutateladze Institute of Thermal Physics
Nizovtsev
Mikhail
nizovtsev@itp.nsc.ru
Novosibirsk, Russia
Kutateladze Institute of Thermal Physics
Sterlygov
Alexei
sterlyagov@itp.nsc.ru
Novosibirsk, Russia
Effect of external facing vapor permeability on humidification of facade materials
In this paper, the influence of the vapor permeability resistance of insulated facades external facing on the moisture content was numerically studied. The calculations were carried out for the climatic conditions of regions with a continental climate with relatively cold winters and warm summers. The WUFI computer program was used to perform heat and humidity calculations. The calculations found that the moisture content of the insulation layer increases with a decrease in the vapor permeability of the external façade facing in the cold season. Thus, the calculations found that with an increase in the resistance to vapor permeability of the external facing Sd > 0.2 m, the average moisture content of mineral wool increases by more than 3 % in the winter period. To reduce the moisture content of insulation, a version of installing an interlayer vapor permeability retarder is proposed. According to calculations, the relationships between the vapor permeability resistances of the external facing and the interlayer retarder were established. The proposed approach using an interlayer retarder can be applied in the development of various designs of building facades with external insulation to protect the insulation layer from humidification during the cold season in regions with a continental climate.
10.34910/MCE.119.8
692.23, 699.86
facade system
heat- insulation layer
external facing
vapor permeability resistance
heat and moisture transfer
calculation model
https://engstroy.spbstu.ru/article/2023.119.8/
RAR
RUS
11909-11909
56966537200
0000-0001-9196-7572
Volgograd State Technical University
Perfilov
Vladimir
vladimirperfilov@mail.ru
Volgograd, Russia
Strength and crack-resistance of concrete with fibre fillers and modifying nano-additives
The article dwells on a comprehensive method for determining concrete strength and crack-resistance in sample testing with varying loading rate. The method allows for receiving simultaneously kinetic parameters of the microstructure defects and length and rate of the main crack growth. The authors consider the impact of effective involved volume on the formation and growth of minor structural defects in cement gel with their eventual phased transition to larger defects. It facilitates increased stress concentration and the development of main cracks at the matrix-aggregate interface. Control over the development of the main crack allows for determining the time till destruction for concrete (longevity). The suggested method and the obtained formula helped applying a wide range of loading rates for determining the critical length of the main crack in concrete. The testing results were used to identify the coefficients of dynamic strengthening for the sample sets with and without an artificially created main crack. These coefficients were applied for calculating the main crack critical length. The article presents the results of experiments aimed at development of concrete compositions comprising fibre fillings and modifying additives including nano-additives followed by determination of their strength and crack-resistance as per the presented comprehensive method. The found values of efficient involving volume, activation energy characterise the microstructure parameters and critical length of the main crack in concrete. The resulting conclusion was that the main crack length in all of the developed concrete compositions exceeded the half of the section in the sample where it developed. Comprehensive assessment of concrete strength and crack-resistance and accumulation of experimental data improve the reliability of scientific research due to the emerging integrated approach to determining quantitative parameters of crack-resistance and longevity of the developed concrete compositions with forecasted properties.
10.34910/MCE.119.9
691.32:620.191.33
concrete construction
stress rates
strength of materials
fibre
nano-additives
crack resistance
methods of analysis
strength criteria
https://engstroy.spbstu.ru/article/2023.119.9/