33407
2304-6295
Construction of Unique Buildings and Structures
4
109
2023
1-60
RAR
RUS
10901-10901
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
Saburov
Daniil Alexandrovich
saburovda@yandex.ru
Gusev
Konstantin Vladimirovich
gusev2.kv@gmail.com
S-4618-2017
57194431559
0000-0003-4992-2084
Peter the Great Saint Petersburg Polytechnic University
Galyamichev
Alexander Viktorovich
galyamichev@yandex.ru
Saint-Peterburg, Russian Federation
Combined behavior of the hinged facade system and reinforced concrete frame of the building under seismic impact
The object of research is an element of system of hinged facade construction. This work aims to study the influence of building frames on the stress–strain state (SSS) of the subsystem of hinged facade systems (HFS) with their joint numerical calculation on the effect of dynamic seismic load. Method. In research the external enclosing structure numerical modeling isolated from the building and together with the reinforced concrete frame of the building. The comparison of SSS and the first natural frequency of the HFS is carried out with an isolated and joint calculation with the building. SSS and the first natural frequency are also compared for various provisions of the HFS. Results. When the HFS is calculated together with the building, the maximum stresses in the subsystem increase up to 5.8 times. The first natural frequency of HFS directly decreases in the range from 1.4% to 7.6%. In this case, the net fluctuations of the HFS occur at the tenth natural frequency of the combined model. The position of the HFS on the facade of the building has little effect on the VAT of the subsystem and does not affect its first natural frequency.
10.4123/CUBS.109.1
69
Numerical modelling
Earthquake action
Hinged ventilated facade (HVF)
Hinged façade system (HFS)
Substructure
Stress and strain state (SSS)
The first natural frequency
https://unistroy.spbstu.ru/article/2023.109.1/
10901.pdf
RAR
RUS
10902-10902
G-1611-2018
56352359500
0000-0002-5156-7352
Volgograd State Technical University
Korniyenko
Sergey Valeryevich
svkorn2009@yandex.ru
Volgograd, Russian Federation
Zenin
Alexander Mikhaylovich
zenin-888@mail.ru
Correlation between sound sources and acoustic quality in urbanized areas
The research object is the urban acoustic environment. The following research methods were used: soundwalk, field measurements of noise levels, narrative interview, and correlation-regression analysis. Soundscapes in various functional city areas have been investigated over three observation periods (morning, afternoon, and evening). A total of 9,450 responses were received from 10 respondents. The noise level in the urban area was measured according to the standard method. Perceived sound sources and their spatial-temporal variations were determined. Spatial-temporal variations of semantic characteristics of emotionally perceived acoustic environment quality were determined. Analysis of the results shows that traffic sounds have a marked inverse correlation with the emotional criterion "pleasantness" in the morning and evening (r = –0.59 and r = –0.55, respectively) and a high inverse correlation (r = –0.76) in the daytime. Traffic sounds have a noticeable inverse correlation with this criterion (r = –0.64). With the criterion "eventful," traffic sounds have a high direct correlation in the morning and afternoon (r = 0.75 and r = 0.72, respectively) and a moderate direct correlation in the evening (r = 0.41). Traffic sounds directly correlate with this criterion (r = 0.61). The human sounds (according to general assessment) do not correlate with the criterion "pleasantness" (r = 0.04); however, the alternating nature of the correlation coefficients (r = –0.50 in the morning and r = 0.34 in the evening) indicates a different emotional perception of colloquial speech at different times of the day. The "eventful" of human sounds is also characterized by a different emotional perception in time: for the morning hours, a high direct correlation is characteristic (r = 0.74); for the daytime hours – weak (r = 0.28); for the evening hours - moderate (r = 0.34). There is a weak positive correlation between the pleasantness and the water sounds, the eventuality, according to the general assessment, is also weakly expressed. Generally, bird sounds positively affect humans in terms of pleasantness (r = 0.38) but is perceived as a non-event effect (r = –0.63). This result is well aligned with the temporal trend of bird singing, particularly the sound dominance in the morning and afternoon hours.
10.4123/CUBS.109.2
69
City
Urban Planning
Acoustic Environment
Soundscape
Soundwalk
Soundtrack
Noise Protection
https://unistroy.spbstu.ru/article/2023.109.2/
10902.pdf
RAR
RUS
10903-10903
Khan
Mohammad Arsalan
mohd.arsalan.khan@hotmail.co.uk
Jafri
Mohd Shamsuddin
jafrims@live.com
Impact response of steel fiber reinforced concrete beams with hooked fibers
The object of research is to investigate the impact response and structural behavior of steel fiber reinforced concrete (SFRC) at varying percentages of fibers by weight of concrete. The impact resistance of plain concrete is low, mainly due to low energy dissipating features and inadequate tensile strength. Steel fibers in concrete mix compensate for the weak tensile properties of conventional concrete. Method. The experimental setup of the impact testing machine is developed to study the impact response of SFRC using a motorized drop hammer on SFRC beam specimens. The average mass of the overall hammer is converted to impact the specimen supported at ends using bolt fixtures. This approach allowed us to evaluate the total strain energy carried by the specimen under impact load. The experimental work also involves testing M20 and M25 concrete grade SFRC cubes under compression using compression testing machine cylinders under split tensile strength test. Results. The results show that as the fiber content increases, the impact strength and the ductility of beams increase. Using fibers enhances all aspects of material capacity, namely compressive strength, split tensile strength, and impact strength.
10.4123/CUBS.109.3
69
Concretes
SFRC
Strength
Stress-strain curves
Impact loads
Drop hammer
Mechanical properties
Strain energy
https://unistroy.spbstu.ru/article/2023.109.3/
10903.pdf
RAR
RUS
10904-10904
15730895100
0000-0003-3251-3356
Saint Petersburg State University of Industrial Technologies and Design
Gorshkov
Alexander Sergeevich
alsgor@yandex.ru
St. Petersburg, Russian Federation
Tyutyunnikov
Anatoliy Ivanovich
A.Tutunnikov@spb.promgaz.gazprom.ru
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
0000-0001-6345-8180
Peter the Great St. Petersburg Polytechnic University
Andreeva (Tarasova)
Daria Sergeevna
andreeva_ds@spbstu.ru
29 Politechnicheskaya St., St. Petersburg, 195251, Russia
57190865804
0000-0002-8136-3246
Peter the Great St. Petersburg Polytechnic University
Olshevskiy
Vyacheslav Ianushevich
79119199526@yandex.ru
St. Petersburg, Russian Federation
The heat flow rejection from double skin facade buffer zones by aeration
The object of research is a ventilated facade with air buffer zones. The problem of heat flow rejection from double skin facade buffer zones by aeration is urgent to reduce the cooling systems load of buildings and reduce energy costs in the summer period. Methods. The article presents a method for calculating heat flow rejection from double-skin facade buffer zones by aeration. The methods is based on the application of the following mathematical equations and calculation methods: the equation of external air density and air in the buffer zone, the equation of gravitational pressure and mass external air flow through the supply hole. Results. The dependence of the heat flow rejection from double skin facade buffer zones by aeration from different internal air temperatures is established and can be represented by a linear dependence of the form The calculation of the heat flow rejection from double skin facade buffer zones by aeration of the Tower high-rise building «Lakhta Center» located in the cold continental climate zone (Dfb) is presented. The heat flow removed from the buffer zone during its aeration is 14676 W. Based on the linear approximation of the dependence graph the following coefficients are obtained: a= – 3873.4; The coefficients can be used to determine the load on the cooling system of the building. The results can be adapted to calculate the heat flow rejection from double skin facade buffer zones by aeration for any façade building with air buffer zones for any climatic conditions.
10.4123/CUBS.109.4
69
High-rise buildings
Enclosure Structure
Heat transfer
Convective
Facades
Double Glazing
Buffer Zone
Thermal Surpluses
Aeration
Air Conditioning
Cooling
https://unistroy.spbstu.ru/article/2023.109.4/
10904.pdf
RAR
RUS
10905-10905
0000-0002-0489-4107
Gorshkov
Rostislav Alexandrovich
rostalsgor@gmail.com
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
0000-0001-6345-8180
Peter the Great St. Petersburg Polytechnic University
Andreeva (Tarasova)
Daria Sergeevna
andreeva_ds@spbstu.ru
29 Politechnicheskaya St., St. Petersburg, 195251, Russia
Cherkashin
Artemiy Viktorovich
cherkashin_av@spbstu.ru
Thermal balance of the high-rise building with translucent modular glazing
Translucent facades are broadly applied in modern architecture, especially in office buildings. Considering the energy use strategies and thermal performance during the initial design process is beneficial for building performance. The object of the research is the translucent glazing facades of high-rise buildings. The research aims to develop a methodology for calculating and evaluating the thermal performance of a high-rise building with translucent modular glazing in the cold season. Methods. A method for calculating and estimating the thermal performance of a high-rise building with translucent modular glazing has been developed and presented. Results. The equation of the thermal balance of the high-rise building with translucent modular glazing is obtained and presented. Based on the obtained equation, the formula for calculating the current indoor air temperature in a heated building is obtained. The indoor air temperature in a heated building depends on the external climatic conditions (outdoor air temperature), thermal performance characteristics of the external enclosing structures, the calculated capacity of the heating system, and the heat storage capacity. The model allows to consider not only the heating system's power but also common and solar heat gain.
10.4123/CUBS.109.5
69
High-rise buildings
Enclosure Structure
Heat transfer
Facades
Thermal balance
Energy Efficiency
Thermal Performance
https://unistroy.spbstu.ru/article/2023.109.5/
10905.pdf
RAR
RUS
10906-10906
H-9967-2013
16412815600
0000-0002-8588-3871
National Research University Moscow Power Engineering Institute
Kirsanov
Mikhail Nikolaevich
mpei2004@yandex.ru
Moscow, Russian Federation
Analytical calculation of the fundamental oscillation frequency of a multi-dome roof
The object of the study is a spatial model of a statically determinate truss of a regular type, consisting of separate domed hexagonal trusses connected in a row. Truss eigenfrequencies are investigated. Method. The lower bound of the first natural frequency is sought in analytical form. The Dunkerley partial frequency method is used. The stiffness of the structure is calculated using the Maxwell – Mohr formula, assuming that the stiffnesses of the elements are the same. The partial frequencies of the masses concentrated in the truss nodes are calculated from separate oscillation equations. Each mass is assumed to have three degrees of freedom. Several solutions for trusses with a successively increasing number of panels are generalized by induction to an arbitrary number of panels. For analytical transformations and calculation of common members of sequences of coefficients of the desired formula, operators of the Maple computer mathematics system are used. In numerical form, the natural frequency spectra of a family of regular trusses are searched for and analyzed. Result. The obtained dependence of the fundamental frequency on the number of panels has coefficients in the form of polynomials of order not higher than the fourth. Comparison of the analytical result with the first frequency of the entire frequency spectrum obtained numerically shows the high accuracy of the found formula. As the number of panels increases, the accuracy of the proposed solution increases. In the frequency spectrum, it is found that the highest frequency of natural vibrations does not depend on the order of the truss.
10.4123/CUBS.109.6
69
Spatial truss
Natural vibrations
Lower frequency estimate
Dunkerley method
Induction
Frequency spectrum
https://unistroy.spbstu.ru/article/2023.109.6/
10906.pdf
RAR
RUS
10907-10907
H-9967-2013
16412815600
0000-0002-8588-3871
National Research University Moscow Power Engineering Institute
Kirsanov
Mikhail Nikolaevich
mpei2004@yandex.ru
Moscow, Russian Federation
Formulas for deflections and a simplified Dunkerley method for calculating the vibration frequency of a planar truss
The object of the study is a scheme of a regular statically defined frame-type truss. The lattice of the truss in the crossbar part of the structure is cruciform. The method of induction in the Maple system of symbolic mathematics derives the analytical dependence of the deflection of the truss and the displacement of the movable support on the number of panels in the crossbar. Maple operators are used to generalize solutions for several trusses with a consistently increasing number of panels for a common case. The calculation of the first oscillation frequency of the structure by the Dunkerley method is simplified by replacing the sum of partial frequencies by calculating the product of the maximum partial frequency by the number of degrees of freedom divided by two. Result. The analytical expression for the frequency depending on the number of panels turns out to be noticeably simpler, and the error of the approximate solution is smaller. The analytical results are compared with the numerical solution.
10.4123/CUBS.109.7
69
Truss
Induction
Deflection
Maple
Fundamental frequency
Dunkerley method
Simplified solution
https://unistroy.spbstu.ru/article/2023.109.7/
10907.pdf
RAR
RUS
10908-10908
B-4397-2014
56826013600
0000-0003-1071-427X
Peter the Great St. Petersburg Polytechnic University
Gravit
Marina Viktorovna
marina.gravit@mail.ru
St. Petersburg, Russian Federation
Nedryshkin
Oleg Vyacheslavovich
nedryshkin@gmail.com
0000-0002-6155-060X
Peter the Great St.Petersburg Polytechnic University
Shabunina
Daria Evgenievna
shabunina_de@spbstu.ru
St.Petersburg, Russian Federation
Shcheglov
Nikita Evgenievich
tsheglov.ne@gmail.com
Shinkareva
Maria Konstantinovna
shinkareva_mk@spbstu.ru
Fire curtains: models of heat transfer in composite materials
The object of research is samples of multilayer protective fabrics for transformable fire barriers installed in buildings and structures to limit the spread of flame, heat flow, and smoke. The work aims to obtain the structure of a transformable fire curtain with fire resistance limits of E60 (loss of integrity) and I30 (loss of thermal insulating capacity). Method. The mathematical simulation method in the software package (SP) ELCUT (Russia), which implements the finite element method, was used to get the temperature distribution along the cross-section of the fire curtain. An experimental study was conducted on a small furnace to confirm the simulation results. Results. Based on the simulation results of eight samples of fire curtains, two promising fabrics were selected that demonstrate a fire resistance limit in terms of loss of thermal insulating capacity (I) of 30 minutes. In small-scale tests, it was found that the best result was the fire curtain containing glass fiber, intumescent mesh, and foil material. The canvas consisting of a single layer of aerogel showed the worst results regarding loss of integrity (E). The simulation results were confirmed by small-scale furnace tests with no more than 10% convergence.
10.4123/CUBS.109.8
69
Fire curtain
Transformable barrier
Fire resistance limit
Thermal insulation capacity
Heat transfer simulation
Aerogel
https://unistroy.spbstu.ru/article/2023.109.8/
10908.pdf
RAR
RUS
10909-10909
57195684636
0000-0001-8800-2657
Voronezh State Technical University
Slavcheva
Galina Stanislavovna
gslavcheva@yandex.ru
Voronezh, Russian Federation
Solonina
Valentina Anatolyevna
soloninava@tyuiu.ru
Panchenko
Yulia Fedorovna
panchenkojf@tyuiu.ru
Orlov
Viktor Sergeevich
orlovvs1@tyuiu.ru
Filipenko
Pavel Vasilyevich
filipenkopv@tyuiu.ru
Effect of aleuropelite content on fresh and hardened properties of 3D-printable multi-binder composites
The object of research is a 3D-printable blended mixture with aleuropelite content. The effect of the aleuropelite dosage and viscosity modifier type on the technological properties and structure formation strength of 3D-build printable mixtures has been investigated. Method. Two types of 3D-built printable mixtures have been used. Their mix design was regulated by the kind of viscosity modifier (metakaolin and combined modifier based on xanthan gum + liquid glass) and dosage of the aleuropelite. Two squeezing tests were used to evaluate the fresh mixture's extrusion ability and shape retention. A high compression speed test using a constant plate speed of 5 mm/s was implemented as the system's behavior in the extrusion process. The squeezing test was conducted with a constant strain rate of 0.5 N/s and was implemented as the system's behavior in the multi-layer casting process. The compressive strength was measured according to Russian Standard GOST 10180-2012 «Concrete. Methods for determining strength from control samples». The SEM-microscopy methods were used to evaluate the microstructure and hydrate phase composition. Results. The plasticity and shape retention of 3D-built printable mixtures depend on aleuropelite content in a binder. The fresh 3D-printable mixtures with 20-30 % aleuropelite dosage in the binder had a plastic yield value of 0.8–1.6 kPa and structural strength of 1.2–5.5 kPa. The strength of 3D-build printable concrete depends on the combination of viscosity modifier type and aleuropelite content in a binder. The combination of metakaolin and aleuropelite as highly active aluminosilicate modifiers causes a high compressive strength (46–56 MPa and 37–65 MPa at seven days and 28 days after production, respectively). The combination of the aluminate phase of metakaolin and aleuropelite in the mix determines the acceleration of the hydration phase formation. The technologically acceptable plasticity shape retention and high strength of 3D-build printable mixtures must be based on hydration process control.
10.4123/CUBS.109.9
69
3D-build printing
3D-printable blended mixtures
Technological properties
Structure formation
Strength
https://unistroy.spbstu.ru/article/2023.109.9/
10909.pdf
RAR
RUS
10910-10910
GMW-6276-2022
0000-0002-3884-874X
Vyatka State University
Ashikhmin
Stanislav Eduardovich
ashihminstanislav@gmail.com
Kirov, Russian Federation
P-3728-2017
57194112309
0000-0001-6184-2365
Vyatka State University
Tyukalov
Yury Yakovlevich
yutvgu@mail.ru
Kirov, Russian Federation
The joint of precast reinforcement frame elements using composite rods
The object of research is a connection of precast reinforced concrete frame elements made using composite rods. This work aims to numerically study the stress-strain state of prefabricated reinforced concrete frame elements' connections. Method. A flat finite element model is used to analyze the stress-strain state of the precast concrete element's connection. The physically nonlinear finite elements are used for concrete modeling. A nonlinear stress-strain diagram for concrete was applied for calculations, given in the regulatory documents for the reinforced concrete structures design. The deformation diagram of steel reinforcement is elastic plastic. Composite rods are deforming elastically. The polyurethane sheets were modeled by nonlinear two-node finite elements working in compression. Results. A numerical analysis of the stress-strain state of a prefabricated frame with the proposed connections of a beam and a column under the action of two loading options has been performed. The results of calculations of prefabricated and monolithic reinforced concrete frames are compared. The comparison results show that the proposed joint connection between the beam and the column provides the required strength and rigidity of the frame.
10.4123/CUBS.109.10
69
Frames
Precast concrete elements
Quickly constructed joint
Composite rods
Epoxy adhesive
Physical nonlinearity
https://unistroy.spbstu.ru/article/2023.109.10/
10910.pdf
RAR
RUS
10911-10911
W-4457-2017
55863846000
0000-0002-1995-6139
Belgorod State Technological University named after V.G. Shukhov, Belgorod, Russsian Federation
Klyuev
Sergey Vasilievich
klyuyev@yandex.ru
Belgorod, Russsian Federation
Lobov
Dmitry Mikhaylovich
d.m.lobov@yandex.ru
External Reinforcement of Wooden Beam Structures with Carbon Fiber Composite Materials
The object of the study is wooden beam structures strengthened by external reinforcement of composite materials based on carbon fiber. This work aims to analyze the distribution of axial strains along the height of the cross-section of a strengthened wooden beam. Method. As part of the experimental study, models of wooden beams strengthened with composite material were tested for static bending. The axial strains of the wooden beam were measured using strain gauges at each loading stage during the testing process. The theoretical values of axial strains at different points along the height of the cross-section were calculated. The cross-sectional characteristics of a reinforced wooden beam were determined for a composite section made of other modulus materials using the reduced section method. Results. The dependence of the change of the strength of wooden beam structures when varying both the parameters of the cross-section geometry and the parameters of external reinforcement is obtained. Diagrams of axial strains at different points along the height of the cross-section were constructed at each stage of sample loading based on the results of the obtained experimental data. The strength increase using the reinforcement system is assessed based on the analysis of tests of reinforced wooden beams and control samples that are not subject to reinforcement. A comparison of the theoretical and experimental values of axial strains of wooden beam structures strengthened by external reinforcement of composite materials based on carbon fiber has been made.
10.4123/CUBS.109.11
69
Carbon Fiber
Carbon Composite Materials
Strengthening of Wooden Structures
External Reinforcement of Wooden Beams
https://unistroy.spbstu.ru/article/2023.109.11/
10911.pdf
RAR
RUS
10912-10912
Maslov
Anton Nikolaevich
maslovanton@list.ru
The first natural frequency of a planar regular truss. Analytical solution
The object of study is the natural oscillations of the rod structure. The first (lowest) oscillation frequency of a flat truss of a regular type is calculated by the Dunkerley method, which gives the lower frequency limit, the Rayleigh method (upper limit), and the simplified Rayleigh formula. Method. The rigidity of the structure is found by the Maxwell-Mohr formula. The stiffness of the rods is the same; the truss nodes are endowed with masses that oscillate vertically. The sum included in the denominator of the Rayleigh formula in the simplified approach is replaced by the value obtained from the deflection with the largest value (at the middle of the span). Results. Compact formulas give the first frequency value for an arbitrary number of panels. It is shown that the simplified Rayleigh method gives a compact formula and good accuracy, which increases with the number of panels.
10.4123/CUBS.109.12
69
Truss
Induction
Maple
Natural frequency
Dunkerley method
Approximate solution
Simplified method
Rayleigh method
https://unistroy.spbstu.ru/article/2023.109.12/
10912.pdf
RAR
RUS
10913-10913
57190865804
0000-0002-8136-3246
Peter the Great St. Petersburg Polytechnic University
Olshevskiy
Vyacheslav Ianushevich
79119199526@yandex.ru
St. Petersburg, Russian Federation
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
Dontsova
Anna Evgenyevna
0000-0001-6345-8180
Peter the Great St. Petersburg Polytechnic University
Andreeva (Tarasova)
Daria Sergeevna
andreeva_ds@spbstu.ru
29 Politechnicheskaya St., St. Petersburg, 195251, Russia
0000-0003-2626-2626
Peter the Great St. Petersburg Polytechnic University
Kotov
Evgeny Vladimirovich
ekotov.cfd@gmail.com
St. Petersburg, Russian Federation
Energy-efficient structures and technologies in additive construction
The object of research is the improvement of the thermal resistance of the buildings’ enclosing structures created with the use of additive technologies. Method. Numerical research, experimental investigations, and secondary analysis of existing data on heat conductance of 3D printed building envelopes were used to investigate the energy efficiency of the building envelopes. The energy efficiency of 3D-printed buildings is based on two main factors: the efficiency of engineering systems and the efficiency of thermal protection. The heat transfer coefficient (U-value) of a 3D-printed wall is influenced by the internal configuration of the wall and by the materials used. The influence of the wall configuration on the U-value of the structure and the efficiency of the insulating material was evaluated based on numerical calculations and CFD modeling data. These two approaches were compared. It was detected that the wall configuration with zigzag internal stiffening diaphragms is the most efficient. The presence of mineral wool insulation in the wall structure increases the heat transfer resistance of the wall, but the efficiency of thermal insulation also depends on the wall configuration. Different wall configurations were investigated, and the change in U-values varied from 32% to 64% when the insulation was considered. Results. The results of empirical calculations of U-values for insulated walls showed extremely low results compared to the U-values obtained from CFD modeling. The high divergence of the results makes it impossible to use the empirical approach to calculate U-values for complex walls. Since 3D-printed walls are mostly made of concrete, the possibility of reducing the thermal conductivity of the concrete was investigated. Aerogel powder in the amount of 15% by volume was added to the concrete mixture. Heat conductivity measures of the manufactured samples showed a 25% reduction average in the heat conductivity of the concrete specimens.
10.4123/CUBS.109.13
69
Enclosing structure
Energy efficiency
Additive technology
Construction 3D printing
Concrete 3D printing
Additive Construction
https://unistroy.spbstu.ru/article/2023.109.13/
10913.pdf
RAR
RUS
10914-10914
Korsun
Vladimir Ivanovich
korsun_vi@mail.ru
Khon
Khemarak
khon.khemarak@gmail.com
Strains and strength of reinforced concrete beams manufacturing by high-strength concrete for non-coincident planes of temperature gradient and loading
The object of research is bent reinforced concrete elements of the beam type manufacturing by high-strength concrete, exposing the effects of uneven heating and loading in non-coincident planes. Method. Experimental research of beam specimens' temperature internal forces, strains, and load-bearing capacity was carried out with characteristic modes of uneven heating and loading in non-coincident planes. Theoretical research was done using the calculation’s special program based on clarified ratios of the nonlinear deformation model. Results. Data from the experimental research, which determine the changes' regularity of temperature internal forces in statical indeterminate bending elements of the beam type manufacturing by high-strength concrete, have been obtained, as well as its strains depending on the temperature and duration of uneven heating. The theoretical and experimental research's results of changes in the stress-strain state of bent beam elements under increasing bending moments until destruction and uneven heating in non-coincident planes have been presented. The temperature moments in reinforced concrete beams under the influences of temperature gradients increase proportionally to the value of the temperature changes, reach a maximum value at the first heating, and decrease after the cracks' formation. The maximum experimental values of temperature moments during one-sided heating of beams up to +90℃ amounted to about 20% of its bearing capacity. The strength of reinforced concrete beams manufactured by high-strength concrete on the bend after one-sided heating within ten days at temperatures up to 90℃ is close to the strength value of the unheated standard beam. This is due to the less sensitivity of high-strength concrete to the action of elevated temperatures in the range up to +90℃. The close accordance of the theoretical and experimental results confirms the reliability of the basic physical relations for the high-strength concrete, which has been implemented in the used option of the nonlinear deformation model of reinforced concrete.
10.4123/CUBS.109.14
69
High-strength concrete
Reinforced concrete beams
Uneven heating
Temperature internal forces
Oblique bend
Strains
Strength
https://unistroy.spbstu.ru/article/2023.109.14/
10914.pdf
REV
RUS
10915-10915
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
0000-0002-7745-4129
Druzhinina
Svetlana Nikolaevna
druzhinina.sn@edu.spbstu.ru
E-6426-2019
56434340300
0000-0002-5694-1737
Peter the Great St. Petersburg Polytechnic University, St. Petersburg, Russian Federation
Usanova
Kseniia Iurevna
plml@mail.ru
St. Petersburg, Russian Federation
Constructions with the use of monolithic foam concrete in fixed formwork
The object of research is constructions with the use of monolithic foam concrete in fixed formwork. The work aims to systematize knowledge about existing structures with foam concrete in fixed formwork, their application areas, advantages, and disadvantages. Method. A review of 90 scientific articles on this topic was carried out. Fifteen types of structures with foam concrete were identified and analyzed. Results. The article describes the characteristics of such a material as foam concrete, as well as its classification. A review of structures with the use of foam concrete in fixed formwork was carried out, and six main areas of application of the material were identified: wall structures, floor structures, roof structures, flooring structures, road pavement, thermal insulation of pipelines, and the advantages and disadvantages of the listed structures were identified.
10.4123/CUBS.109.15
69
Monolithic foam concrete
Fixed formwork
Foam concrete structures
https://unistroy.spbstu.ru/article/2023.109.15/
10915.pdf
RAR
RUS
10916-10916
0000-0001-5679-2084
Kraev
Andrey Nikolaevich
kraev-an@mail.ru
0000-0002-0274-0673
Maltseva
Tatyana Vladimirovna
maltsevatv@tyuiu.ru
57217593029
0000-0002-8983-3898
Tashkent institute of irrigation and agricultural mechanization engineers
Abdullayev
Akmaljon Abdujalilovich
akmal09.07.85@mail.ru
Tashkent, 100000 st. Khari Niyaziy 39
Interaction of a sand cushion with a viscoelastic soil base
The object of research is a sand cushion with contour reinforcement placed in a viscoelastic clay soil base. The work aims to analyze the stress-strain state of the reinforced soil massif. Method. Research of the soil array at the first stage of work is carried out on small-scale models in laboratory conditions. Quantitative assessment of the stress-strain state is performed on large-scale foundation models in the field. Results. Based on the results of experimental data, the dependences of the deformation of a soil mass reinforced with a sand cushion with contour reinforcement were established. A decrease in the vertical settlement of the foundation was revealed due to a decrease in shear deformations in the body of the sand cushion. A comparison of numerical modeling with experimental results showed good convergence, with a discrepancy between the results by 20-30%. A constructive solution for strengthening a weak base in the form of a sand cushion with contour reinforcement makes it possible to reduce the creep of the base, increasing the linear stage of its work.
10.4123/CUBS.109.16
69
Weak clay soils
Sand cushions
Reinforcement
Creep
Viscoelastic properties
https://unistroy.spbstu.ru/article/2023.109.16/
10916.pdf
RAR
RUS
10917-10917
Mushchanov
Vladimir Filippovich
mutshanov_vf@spbstu.ru
Mushchanov
Alexander Vladimirovich
mutshanov_av@spbstu.ru
Tsepliaev
Maksim Nikolaevich
m.n.cepliaev@donnasa.ru
Orzhehovskiy
Anatoly Nikolaevich
aorzhehovskiy@bk.ru
Stability of spatial structural elements: the influence of actual modeling
The object of research is the elements of spatial metal structures – space frames and tanks. The purpose of this work is to refine the parameters of the stress-strain state of the rod elements of structural coatings and walls of vertical cylindrical tanks, which is performed when assessing their stability. Method. The actual modeling of all structural elements was chosen as the method for studying the stress-strain state. The calculation schemes are implemented in the LIRA-SAPR software package (https://www.lirasapr.com) in geometrically and physically non-linear formulations. This solution allows you to track the nonlinear work between the load-displacement relationship as much as possible. Results. As a result, for the centrally compressed rods of structural structures, a dependence has been established that makes it possible to refine their bearing capacity from the stability condition. For the walls of vertical cylindrical tanks, the question of the influence of spiral staircases on the stability of the wall was studied.
10.4123/CUBS.109.17
69
Spatial metal structures
Space frames
Tanks
Sheet structures
Stress-strain state
Structures simulation
Finite element method
Stability
Static loads
Plasticity
https://unistroy.spbstu.ru/article/2023.109.17/
10917.pdf
RAR
RUS
10918-10918
H-9967-2013
16412815600
0000-0002-8588-3871
National Research University Moscow Power Engineering Institute
Kirsanov
Mikhail Nikolaevich
mpei2004@yandex.ru
Moscow, Russian Federation
Formula for natural frequency oscillation truss with an arbitrary number of panels
The object of research is the problem of the first frequency of free vibrations of a planar statically determinate regular beam truss with a mass uniformly distributed over the nodes. Method. The problem is solved in the Maple computer mathematics system in symbolic form. The masses oscillate along the vertical axis. The solution is sought using the Dunkerley method. The induction method and Maple operators were used to generalize a series of analytical solutions for trusses with a successively increasing number of panels. Results. The results are compared with a numerical solution obtained as the minimum frequency of the entire frequency spectrum and a simplified version of the Dunkerley method. It is shown that the accuracy of analytical solutions increases with an increase in the number of panels. The spectra of a family of regular trusses of various orders are analyzed numerically. Spectral constants, spectral isolines, and resonant safety regions have been identified.
10.4123/CUBS.109.18
69
Truss
Induction
Maple
Fundamental frequency
Dunkerley method
Simplified solution
Spectral constants
Resonant safety regions
https://unistroy.spbstu.ru/article/2023.109.18/
10918.pdf
RAR
RUS
10919-10919
Kavkazskiy
Vladimir Nikolaevich
кavkazskiy_vn@mail.ru
0000-0002-3142-6018
Peter the Great St. Petersburg Polytechnic University
Kirsanova
Tatiana Aleksandrovna
kirsanova_ta@spbstu.ru
E-6426-2019
56434340300
0000-0002-5694-1737
Peter the Great St. Petersburg Polytechnic University, St. Petersburg, Russian Federation
Usanova
Kseniia Iurevna
plml@mail.ru
St. Petersburg, Russian Federation
0000-0002-7422-5494
Peter the Great St.Petersburg Polytechnic University
Vafaeva
Khristina Maksudovna
vafaeva_hm@spbstu.ru
Saint Petersburg, Russian Federation
0000-0003-4599-8938
Vasyutkin
Evgenii Sergeevich
evasyutkin@yandex.ru
Drainage bridge trays made of glass fiber reinforced polymer: physical, mechanical and operational properties
The object of research is a drainage bridge tray made of glass fiber-reinforced polymer. This work aims to study the physical and mechanical characteristics of glass fiber-reinforced polymer used to produce drainage bridge trays and determine the operational characteristics of a typical suspended drainage tray. Method. Experimental studies are carried out to determine the physical and mechanical characteristics of fiberglass: density, water absorption, Barcol's hardness, compressive strength, tensile strength, compressive modulus of elasticity, and tensile modulus of elasticity. The operational properties of a typical suspended drainage tray are determined using hydraulic calculations. Results. The physical and mechanical characteristics of glass fiber-reinforced polymer are suitable when exposed to aggressive environments in difficult climatic conditions, including producing drainage structures for bridge roadways. The density of the glass fiber reinforced polymer is 1770 kg/m3; water absorption is 0.42%, Barcol's hardness is 41 units, compressive strength in the direction 0°/90° is 108.3 MPa/100.4 MPa, tensile strength in the direction 0°/90° is 165.8 MPa/150.1 MPa, modulus of elasticity in compression in the direction 0°/90° is 11.7 GPa/9.7 GPa, modulus of elasticity in tension in the direction 0°/90° is 13.9 GPa/10.0 GPa. The proposed design solution for a drainage bridge tray made of glass fiber reinforced polymer ensures the passage of the calculated flow rate of rainwater runoff 125.71 l/s when filled, not exceeding the maximum allowable.
10.4123/CUBS.109.19
69
Fiberglass composite
Glass fiber reinforced polymer
Bridges drainage system
Strength
Elastic modulus
Water absorption
Density
Barcol's hardness
https://unistroy.spbstu.ru/article/2023.109.19/
10919.pdf
RAR
RUS
10920-10920
0000-0002-4879-6699
South Ural State University
Zadorin
Aleksandr Aleksandrovich
zadorinaa@susu.ru
Chelyabinsk, Russian Federation
57190961036
0000-0003-4021-003X
South Ural State University
Mishnev
Maxim Vladimirovich
mmv2004@list.ru
Chelyabinsk, Russian Federation
12039592100
0000-0003-4283-0400
South Ural State University
Korolev
Aleksandr Sergeevich
korolev@sc74.ru
Chelyabinsk, Russian Federation
Temperature stress accumulation in polymer composite shells under cyclic temperature impact
The object of research is a polymer composite based on thermosetting epoxy binder and EZ-200 fiberglass fabric. Its behavior in the operating conditions of industrial chimneys, which include high temperatures, long-term operation, cyclic mechanical and temperature impact, and prolonged thermal aging, is yet to be determined. Viscoelasticity of polymer matrix leads to several possible effects. One is the accumulation of temperature stresses due to non-stationary temperature effects. This work aims to evaluate the possibility of such an effect and assess it. It required us to conduct cyclic heating tests and FE shell calculations. Method. Cyclic heating tests were conducted in the specially manufactured testing chamber, which allowed us to prevent specimens from longitudinal deformations, illustrating the work in constrained construction conditions. Specimens were exposed to several heating and cooling cycles, while the longitudinal force was measured during the experiment and converted to stress. To check the adequacy of the equipment and for further calculations, the elastic modulus was calculated through tensile tests. Results. It was observed that the stress amplitudes were not the same during the heating-cooling cycles. There was a shift in the compressive stress direction, meaning the possible accumulation of temperature stresses. Calculations of temperature stresses using The Coefficient of Thermal Expansion (CTE) indirectly proved that. The 3-layered sandwich shell of an industrial chimney was calculated using ANSYS Workbench software to assess the influence of stress accumulation on the stress-strain state of the construction. It showed us that there might be a 5-10% increase in stress. Therefore, it should be considered, and further research on this topic is needed.
10.4123/CUBS.109.20
69
Polymers
Composites
Thermal loads
Viscoelasticity
Stress accumulation
Industrial chimneys
Gas ducts
https://unistroy.spbstu.ru/article/2023.109.20/
10920.pdf
RAR
RUS
10921-10921
Antoshkin
Vasily Dmitrievich
antovd@mail.ru
Sagaidak
Maksim Olegovich
sagmaxim81@gmail.com
Dyugaev
Aleksandr Sergeyevich
san9i1998@mail.ru
N-5479-2017
57194779967
0000-0002-6959-0008
(a) Division of Research and Development, Lovely Professional University, Phagwara, Punjab, India; (b) Peter the Great St. Petersburg Polytechnic University, Saint Petersburg, Saint Petersburg, Russia
Dixit
Saurav
sauravarambol@gmail.com
Formation of spatial structural coverings
The object of research is spatial structural coatings of buildings and methods of their formation. Areas of use of structural structures are premises of hall buildings and warehouses. Method. A method for solving problems of geometric and structural-technological formation of structures using graphic computer means and analytical methods using a mathematical model is known. Analytical methods of structural and technological formation of structures in the form of polygonal networks on the sphere, which were called "Antants," have been developed. The algorithm of the analytical solution of the problem of placing a triangular network on a sphere with the formation of quadrangular flat panels in the belts of the structure for building coverings is presented. Results. Results of formation of double-belt shells on the basis of spherical surfaces are presented, and version of structure on the basis of transfer surface is shown. Optimality and efficiency criteria for options are the minimum number of standard sizes of structural parts and the minimum number of mounting structural elements, the possibility of increased assembly of panels and volume blocks, the use of prestressing. The developed methods of forming the geometry of prefabricated spatial blocks of building structures "Antants" were used to cover buildings for various purposes.
10.4123/CUBS.109.21
69
Prefabricated spatial structure
Spherical shell
Constructive and technological solution
Panel
Regular quadrangle
Cut
Pyramid
https://unistroy.spbstu.ru/article/2023.109.21/
10921.pdf
RAR
RUS
10922-10922
Saryan
Levon Levonovich
adm@kgtu.kuban.ru
The existing buildings with retaining structures
The object of the research is the retaining wall behavior under conditions of complex topography and dense development of existing buildings. The influence of retaining wall construction on the stress-strain state of the existing structures is also investigated. This work aims to evaluate the impact of soil cutting and constructing a retaining wall adjacent to the existing building. This research is of great importance as there is a lack of knowledge of appropriate structural solutions for earth-retaining structures considering landslide protection measures and distance between structures. Method. Numerical calculations were performed in the Plaxis 3D software program for three-dimensional calculations of the deformation and stability of spatial construction objects and the soil base. The work was divided into three stages: 1) building construction, 2) arrangement of landslide control measures, and 3) excavation for new construction. At each stage, changes in the forces occurring in the foundation slab, columns, and perimeter beams were analyzed. A comparative analysis with the previous stage was carried out. Results. The impact of the newly erected retaining wall on the structures of the existing buildings was calculated. Changes in displacements of slab foundation, transverse, and longitudinal forces, as well as bending moment in building structures depending on the height and distance of adjacent structures, were determined. Recommendations for making optimal design decisions that help minimize the negative impact on the existing structures are given.
10.4123/CUBS.109.22
69
Retaining wall
Negative effect
Existing structure
Slope stability
Foundation slab
Landslide control
Displacement
Influence of a deep excavation
https://unistroy.spbstu.ru/article/2023.109.22/
10922.pdf
RAR
RUS
10923-10923
0009-0007-6899-3810
South Ural State University
Astashkin
Vladimir Mihailovich
avm1940@mail.ru
57190961036
0000-0003-4021-003X
South Ural State University
Mishnev
Maxim Vladimirovich
mmv2004@list.ru
Chelyabinsk, Russian Federation
0000-0002-4879-6699
South Ural State University
Zadorin
Aleksandr Aleksandrovich
zadorinaa@susu.ru
Chelyabinsk, Russian Federation
12039592100
0000-0003-4283-0400
South Ural State University
Korolev
Aleksandr Sergeevich
korolev@sc74.ru
Chelyabinsk, Russian Federation
0009-0008-9294-0580
Alabugina
Daria Artemovna
alabugina_darya@mail.ru
Pyankova
Anastasia Yurievna
asapankova06390@gmail.com
Shamberger
Albina Andreevna
albinaraidel@gmail.com
Structural multi-element model of viscoelastic material: concept and experimental testing
The object of research. The paper presents the results of experimental studies and mathematical modeling of stress formation in thermoplastic polymer (vinyl plastic) under cyclic thermomechanical loading. Stress accumulation occurs under cyclic thermomechanical loading in a pinched rod, similar effects are observed, for example, in thermoplastic elements subjected to joint mechanical loads and variable temperatures. Method. A multi-element structural mathematical model with memory for thermomechanical loading is proposed, which allows to consider the accumulation of residual thermal stresses. Results. The results of modeling and experiment are compared. According to the results, corrections in the approach to the application of this model have been made. Considering the corrections, good agreement with the results of experimental determination of stresses under complex cyclic thermomechanical loading is obtained. The ways of further development of the proposed approach are outlined.
10.4123/CUBS.109.23
69
Thermoplastic polymers
Composites
Thermomechanical loading
Viscoelasticity
Stress accumulation
https://unistroy.spbstu.ru/article/2023.109.23/
10923.pdf
RAR
RUS
10924-10924
Grishin
Ilya Valerevich
il6357grishin@yandex.ru
Petropavlovskikh
Olga Konstantinovna
olga_konst@mail.ru
Ibragimova
Aniia Airatovna
anyia13@mail.ru
Stress strain state of asphalt concrete pavements of steel bridges
The object of research is the stress-strain state of asphalt concrete pavements of steel bridges with an orthotropic slab under traffic load. Research is necessary because one of the main problems of steel bridge deck pavements is the formation of longitudinal cracks in asphalt concrete above the main beams of superstructures. At the same time, there are no instructions in the engineering standards to prevent the appearance of such a crack. The lack of clear instructions, in turn, is because the stress-strain state of the roadway of metal bridges has features that have not been studied sufficiently. Method. The primary research method uses a software package that implements the finite element method. During modeling, shell finite elements are used to model the metal span, and three-dimensional finite elements are used to model the protective-cohesive and asphalt concrete layers. A three-axle truck was considered as a wheel load under various loading schemes. In addition, the physical and mechanical parameters of the protective layer and asphalt concrete were evaluated at different rent temperatures, on which they largely depend. Results. As a result of modeling the superstructure section, it was found that tensile stress occurs in the upper fiber of asphalt concrete above the main beam. And the closer the wheel is to the main beam, the greater this stress can lead to future cracks. However, a phenomenon has been found that at sufficiently high temperatures, the highest tensile stresses in the top fiber of asphalt concrete occur near the wheel. In contrast, the highest tensile stresses always occur above the main beam at sub-zero temperatures. Considering that cracks in asphalt concrete arise as a result of the gradual accumulation of damage and assuming that the traffic load moves mainly along the wheel path zone, it can be concluded that the spacing of the wheel path and walls of the main beams in space can lead to an increase in the service life of asphalt concrete pavements of metal bridges
10.4123/CUBS.109.24
69
Asphalt
Steel bridge
Finite element modeling
Bridge deck pavement
Cracks in asphalt
https://unistroy.spbstu.ru/article/2023.109.24/
10924.pdf
RAR
RUS
10925-10925
Belov
Vyacheslav Vasilievich
belovvv@mgsu.ru
Verkhovskiy
Roman Dmitrievich
roman.verhovskii@mail.ru
Nikolaev
Georgy Alekseevich
nikolaev.georgy.al@gmail.com
Mikheev
Stepan Anatolyevich
mikheevs.sea@gmail.com
Seismic resilience frames of industrial buildings with energy absorbers
The object of research is the seismic resilience of industrial buildings with a frame design of the structural scheme. Increasing seismic resilience, especially for energy facilities, is promising. With the change in the regulatory and technical base of the Russian Federation, it is necessary to search and analyze new design options that would increase the survivability of the building while being economically justified. Therefore, this paper considers the use of methods for improving seismic resistance through elements for absorbing vibrational energy during the implementation of a special seismic effect, working elastoplastically. Method. A detailed numerical analysis of the operation of the industrial building frame's structural system was carried out using the finite element method in modern software systems based on the example of a thermal power plant (TPP) with a gas turbine with a capacity of 170 MW in two versions with energy-absorbing structures of details and a "traditional" version. Results. As a result, the prospects for using energy absorption elements in frame-braced structures of the frame of the TPP building were substantiated. It has been established that such solutions make it possible to concentrate most of the residual deformations in themselves, thereby reducing the deformability of other structural elements, increasing the overall survivability of the frame, and reducing the volume of restoration during the implementation of seismic impact. A quantitative assessment was given of the change in the operation of the frame of a TPP with a 170 MW gas turbine equipped with energy absorbers during the implementation of a seismic impact.
10.4123/CUBS.109.25
69
Seismic resilience
Industrial buildings
Energy Absorbers
Survivability of a steel frame
Numerical analysis
Main building of a thermal power plant
Plastic deformations
https://unistroy.spbstu.ru/article/2023.109.25/
10925.pdf
RAR
RUS
10926-10926
Kareeva
Juliya Rustemovna
jkareeva2503@gmail.com
Chukhlova
Mariya Borisovna
mariachukhlova@gmail.com
Ziganshin
Arslan Malikovich
amziganshin@kgasu.ru
Logachev
Konstantin Ivanovich
kilogachev@mail.ru
Tussupova
Kamshat
kamshat.tussupova@mail.ru
Numerical model of the flow in the exhaust unit "opening – elbow"
The object of research is the unit of the ventilation system, "exhaust opening - elbow." Ventilation systems designed in buildings for various purposes are usually highly branched, leading to significant pressure losses, the largest of which is due to local resistance in duct fitting elements. The design features of the premises and the significant dimensions of the ventilation ducts lead to the need to route the air ducts with fitting elements installed side-by-side. In such cases, one element has a mutual influence on another, with a change in comparison with separate ones, both in the coefficients of local resistance and the total pressure loss, which is not considered when performing aerodynamic calculations nowadays. Method. The article investigates the ventilation system unit, consisting of an elbow and an exhaust opening, spaced significantly large apart for testing purposes. Outlines of the vortex zones and the local drag coefficients of individual elements included in the unit are determined in the study. Results. As a result, outlines of the vortex zones at the inlet of the exhaust opening and in the elbow were obtained. The local drag coefficients for the exhaust opening and elbow were calculated. The obtained results were compared with known experimental and numerical data. The comparison of the obtained results showed that the settings used in this study led to adequate results in determining the outlines of the vortex zones and the local drag coefficients. The chosen model will be further used to study the influence of the elbow-exhaust opening distance on flow characteristics.
10.4123/CUBS.109.26
69
Ventilation system
Duct fitting elements
Unit "exhaust opening - elbow"
Numerical method
Vortex zones
Local drag coefficient
https://unistroy.spbstu.ru/article/2023.109.26/
10926.pdf
RAR
RUS
10927-10927
0000-0002-0649-4342
Vdovin
Evgeny Anatolievich
vdovin007@mail.ru
Kazan, Russian Federation
0000-0002-0149-8854
Kazan State University of Architecture and Engineering
Bulanov
Pavel Efimovich
pavel.bulanov1991@yandex.ru
Kazan, Russian Federation
0000-0001-9680-6698
Kazan State University of Architecture and Engineering
Stroganov
Victor Fedorovich
svf08@mail.ru
0000-0002-9713-2805
Morozov
Vladimir Petrovich
vladimir.morozov@kpfu.ru
Construction of road pavements using complex modified soil-cement
The object of research is the pilot industrial implementation of complex modified soil-cement in the construction of bases for flexible road pavements. The work aims to analyze the results of the pilot industrial implementation of soil cement modified with organosilicon compounds, polycarboxylate superplasticizers, and electrolytes in constructing bases for flexible road pavements. Method. The construction of road base layers from soil cement was done using the on-site mixing method. The construction of the remaining structural elements of the road structure (subgrade, asphalt concrete pavement) of the highway was carried out using standard technologies. The dynamic loading method determined the elastic modulus of the road pavement layers, the entire structure, and the roadbed soil by the static loading method. The effectiveness of the development and the legitimacy of the implemented scientific approach to the complex modification of soil cement was assessed by comparing the results of laboratory studies and industrial tests on highways. To determine the mineralogical composition and identify the products of new formations of soil-cement, X-ray phase, and differential thermal analysis methods were used. Results. A comparative analysis of laboratory research results and pilot industrial implementation of complex modified soil-cement and reinforced soils without modification during highway construction was carried out according to the following indicators: physical and mechanical properties, phase composition, and elastic modulus of the layer. Transitional-type road pavement designs with soil-cement foundations have been developed. The technology for carrying out work on the construction of a highway has been determined, including installing structural layers of the base of road pavements from cement soils using the on-site mixing method. The optimization of the compositions of complex-modified soil cement was carried out using the second-order rotatable planning method. Based on the developed road pavement designs, work technology, and optimization of the soil-cement composition, a highway was built with the construction of two sections to compare the effectiveness of the modification. Research has been carried out to determine and compare the elastic moduli of layers of road pavements and subgrades. The validity of the implemented scientific approach to using complex modification of soil-cement in constructing structural layers of road pavements has been confirmed.
10.4123/CUBS.109.27
69
Soil-cement
Road pavement
Clay soil
Pilot experimental-industrial introduction
Complex modification
https://unistroy.spbstu.ru/article/2023.109.27/
10927.pdf
RAR
RUS
10928-10928
0000-0002-0649-4342
Vdovin
Evgeny Anatolievich
vdovin007@mail.ru
Kazan, Russian Federation
0000-0002-0149-8854
Kazan State University of Architecture and Engineering
Bulanov
Pavel Efimovich
pavel.bulanov1991@yandex.ru
Kazan, Russian Federation
0000-0001-9680-6698
Kazan State University of Architecture and Engineering
Stroganov
Victor Fedorovich
svf08@mail.ru
0000-0002-9713-2805
Morozov
Vladimir Petrovich
vladimir.morozov@kpfu.ru
Complex modification of soil cement for road pavements
The study's relevance is justified by the need to ensure the required strength and frost resistance of soil-cement layers of road pavements in road-climatic zones with seasonal and daily temperature changes, especially with frequent transitions through 0 °C. The object of research is modified soil cement for road pavements. This work aims to develop soil-cement compositions with complex modification with an organosilicon compound, a polycarboxylate superplasticizer, and an electrolyte. Method. The compositions of complex-modified soil cement were optimized using the second-order rotatable planning method. Potassium methylsiliconate, polycarboxylate superplasticizer, and sodium hydroxide percentages were selected as variable factors. The X-ray phase analysis method used an automatic X-ray diffractometer Bruker D8 Advance to determine the mineralogical composition and identify the products of new formations during the hardening of modified soil cement. The construction and analysis of diffraction patterns were performed using the Bruker Diffrac Eva program. Results. It was established that the complex modification of soil-cement with potassium methyl silicone, polycarboxylate superplasticizer, and sodium hydroxide provided an increase in the compressive strength by 95 %, the tensile strength in bending by 132 %, and the frost resistance coefficient by 129 % with a Portland cement content of 8 %. Strength grade M40 and frost resistance grade F15 were achieved with the introduction of Portland cement in an amount of 8 % and a complex of modifiers: potassium methyl siliconate – 0.4 %, polycarboxylate superplasticizer – 0.35 %; sodium hydroxide – 0.1 %. X-ray phase analysis was used to establish that introducing a complex of modifiers into cement soils increases the amount of portlandite by 81 %, calcium hydrosilicates by 50 %, and reduces the content of residual clinker minerals C3S and C2S by 61 %. An increased amount of amorphous phase from 27 % to 29.9 % in the form of tobermorite gel in cement soils indicates a more significant number of new formations. The main reflection of calcite CaCO3, as a product of calcium hydroxide carbonation, is reduced in the modified cement soil sample by 18.9 %.
10.4123/CUBS.109.28
69
Soil-cement
Organosilicon compound
Polycarboxylate superplasticizer
Electrolyte
Optimization
Complex modification
https://unistroy.spbstu.ru/article/2023.109.28/
10928.pdf
RAR
RUS
10929-10929
0000-0003-4902-6167
Kazan State University of Architecture and Engineering
Mirsayapov
Ilshat Talgatovich
mirsayapovit@mail.ru
Kazan, Russian Federation
Apkhadze
Georgiy Tateozovich
georgevt@yandex.ru
0000-0003-4283-0400
Kazakhstan Multidisciplinary Institute of Reconstruction and Development Republican State Enterprise on the Right of Economic Use
Nuguzhinov
Zhmagul Smagulovich
kazmirr@mail.ru
Karaganda, Kazakhstan
Strengthening of concrete beams by CFRP considering initial state
The object of research is the bearing capacity of normal sections of bendable reinforced concrete structures, reinforced in the tensile zone with high-strength carbon fiber-reinforced plastic materials. The purpose of research is to analytically obtain the most universal and accurate dependence for determining the limiting bending moment of elements reinforced in a tensile zone with carbon fiber-reinforced plastic materials, taking into account their initial state before strengthening during failure of the concrete compressed zone. The objectives of research are: analytically obtaining the dependence for the height of the compressed zone of concrete in the section in the limit state after strengthening, taking into account the initial stress state; comparison of the load-bearing capacity obtained taking into account the presented dependencies, according to the dependencies adopted in the current regulatory documents, as well as according to the nonlinear deformation model. Method. The work adopted the basic techniques used in the modern theory of strength of concrete and reinforced concrete, as well as in the mechanics of anisotropic deformable solids. Results. The obtained analytical expressions for determining the limiting bending moment perceived by normal sections of reinforced concrete elements reinforced with carbon fiber-reinforced plastic materials in the tensile zone make it possible to consider the initial stress-strain state and the degree of its influence on the strength of such elements. A reasonable refinement of the analytical dependencies of the normative approach makes it possible to achieve good convergence with the results of calculations using a nonlinear deformation model. The proposed analytical dependencies make it possible to determine the actual strength of normal sections of reinforced bending elements, considering the initial stress-strain state without the need for complex iterative calculations.
10.4123/CUBS.109.29
69
Structures of buildings
Reinforced concrete
Concrete
Beams
Composite materials
Reinforcement
Carbon fiber-reinforced plastic
CFRP
Fiberglass
Strengthening of structures
https://unistroy.spbstu.ru/article/2023.109.29/
10929.pdf
RAR
RUS
10931-10931
Aksenkin
Vitalij Ivanovich
vit_aks74@mail.ru
0000-0002-5616-1191
Peter the Great St. Petersburg Polytechnic University
Lazarev
Yuriy Georgievich
lazarev-yurij@yandex.ru
Saint Petersburg, Russian Federation
E-6426-2019
56434340300
0000-0002-5694-1737
Peter the Great St. Petersburg Polytechnic University, St. Petersburg, Russian Federation
Usanova
Kseniia Iurevna
plml@mail.ru
St. Petersburg, Russian Federation
0000-0002-7422-5494
Peter the Great St.Petersburg Polytechnic University
Vafaeva
Khristina Maksudovna
vafaeva_hm@spbstu.ru
Saint Petersburg, Russian Federation
0000-0003-4599-8938
Vasyutkin
Evgenii Sergeevich
evasyutkin@yandex.ru
Mechanical properties of fiber-reinforced polymer bars under various types of stress-strain state
The object of research is fiber-reinforced polymer bars of a periodic profile with diameters of 4 mm, 6 mm, 8 mm, 10 mm, and 12 mm, manufactured by pultrusion-pulling glass fiber impregnated with a liquid epoxy resin-based binder through a round die. This work aims to study the physical and mechanical characteristics of fiberglass rods used for reinforcement concrete structures. Method. Experimental studies are conducted to determine the physical and mechanical characteristics of glass fiber-reinforced polymer rebar and compare the mechanical characteristics of glass fiber-reinforced polymer bars with steel bars of classes A-III and A-IV. Results. The experimentally established physical and mechanical characteristics of fiberglass reinforcement show the following values: tensile strength is 1080-1338 MPa, compressive strength is 405-520 MPa, transverse shear strength is 218-250 MPa, bond strength with concrete is 12.6-15.9 MPa, elastic modulus is 50.7-54.2 GPa. After keeping the specimens in an alkaline environment, the bond strength of the bars to concrete decreased by 5-21% for rod diameters of 4 mm, 6 mm, and 12 mm, and tensile strength decreased by 6-10% for rod diameters from 4 mm to 10 mm. The maximum operating temperature for glass fiber-reinforced polymer rebar is 92 °C - 101 °C, depending on the diameter. In terms of its mechanical characteristics, glass fiber-reinforced polymer rebar is superior to steel reinforcement in all respects, except for the modulus of elasticity, which is almost four times lower than that of steel rebar. The average value of the tensile strength of glass fiber reinforced polymer rebar is 65% higher than that of steel rebar, the tensile strength is 23% higher, and the bond strength with concrete is 80% higher.
10.4123/CUBS.109.31
69
Fiberglass composite
Glass fiber reinforced polymer
Strength
Elastic modulus
Concrete
Rebar
https://unistroy.spbstu.ru/article/2023.109.30/
10931.pdf
RAR
RUS
10932-10932
C-6381-2019
56226922300
0000-0002-9445-5027
Peter the Great St. Petersburg Polytechnic University
Korsun
Volodymyr Ivanovich
korsun_vi@mail.ru
St. Petersburg, Russian Federation
57194445595
0000-0001-8517-9705
Peter the Great St. Petersburg Polytechnic University
Vinogradova
Natalya Anatolevna
natasha-vinograd@mail.ru
St. Petersburg, Russian Federation
Steel-reinforced concrete elements strengthened by the anchoring method
The object of research is steel-reinforced concrete elements in which various anchoring methods provide the joint work of concrete and steel. Method. The results of experimental studies of the bearing ability to shift the units of a galvanized sheet profile with a reinforced concrete structure concerning the beams of the Marco-UNIVIVERSAL system and the development of a methodology for the calculated determination of the limit voltages in the designs of thin-leaf rolling. Four methods of connecting rental sheets with concrete design have been implemented: without special anchors due to the adhesive ability of cement stone; with the help of frozen ones at the stage of manufacturing the design of anchor bolts; with the aid of steel dowels scored in concrete durability; With the help of bends inside the concrete block sections of the sheet rolling profile. Regarding shifting efforts, at the time of the destruction of the compounds, the maximum stresses are determined in the profile sheets, recommended as calculated resistances. Results. Conclusions have been drawn about the most optimal ways of surveying the sheet profile in concrete from the standpoint of its most complete inclusion in the work as part of steel-reinforced concrete structures, as well as considering the manufacturability of the installation of anchor devices at the construction site.
10.4123/CUBS.109.32
69
Steel-reinforced concrete
Thin steel profile
Anchoring methods
Shear test
Deformations
Tension
Calculation
https://unistroy.spbstu.ru/article/2023.109.31/
10932.pdf