75504
2712-8172
Magazine of Civil Engineering
17
5
2024
RAR
RUS
12901-12901
57201536233
Karpenko
Nikolaj
Russian Academy of Architecture and Building Sciences
karpenko@raasn.ru
Moscow, Russia
0000-0000-0000-0001
Karpenko
Sergey
Research Institute of Building Physics
niisf@niisf.ru
Moscow, Russian Federation
55534147800
0000-0001-5290-3429
Kolchunov
Vladimir
Southwest State University
sjs28@mail.ru
Kolchunov
Vitaly
Southwest State University
asiorel@mail.ru
Deformation of box-sectional structures during torsion with bending
The article is devoted to the problem of complex stress state of reinforced concrete under the action of torsion with bending, taking into account axial and transverse forces. The existing calculation models remain imperfect, despite a significant number of publications in the world on this problem. They are fragmentary and sometimes contradictory and consider individual special cases of stress. The proposed version of the deformation model is based on physical relations for reinforced concrete, static equations and conditions for compatibility of deformations in the design section at the stage after the crack formation. The calculation model takes into account all the components of external forces in the rod element, the spatial nature of cracks, various cases of the location of the compressed concrete zone or its absence, depending on the ratio of the acting forces in the design structure. The obtained analytical dependences allow one to determine interconnected design parameters, such as stresses in the concrete of the compressed zone, the height of the compressed concrete, stresses in axial and transverse rods, deformations in concrete and reinforcement, curvature and twisting angle of a reinforced concrete element, while simultaneously applying a twisting and bending moments, axial and transverse forces to the element. The deformation model obtained in the article can be used in the design of a wide class of reinforced concrete structures under the action of torsion with bending taking into account axial and transverse forces in the calculated element.
10.34910/MCE.129.1
624.012.45
reinforced concrete
torsion
bending moment
axial load
combined action
box section
https://engstroy.spbstu.ru/article/2024.129.1/
RAR
RUS
12902-12902
57170021900
0000-0003-3687-0510
Chesnokov
Andrei
Lipetsk State Technical University
andreychess742@gmail.com
Lipetsk, Russian Federation
57170132800
0000-0001-8274-9346
Mikhailov
Vitalii
Lipetsk State Technical University
mmvv46@rambler.ru
Lipetsk, Russian Federation
Cable roof with stiffening girder and flexible membrane shell
The framework of the roof, considered in the research, is a two-chord truss-like structure. The chords are joined by vertical struts. They are made of high-strength steel cables. A flexible polymer membrane is attached to the restraining chord. The opposite supports of the roof are joined by a girder made of ordinary structural steel. The girder mitigates deformations of the truss under non-uniform external loads. It is loosely connected to the vertical struts. The loose connections (so-called design clearances) prevent overstressing the girder by uniform impacts. Computational technique for static analysis of the cable roof is proposed. The main structural parameters are estimated under the condition of the full use of the material properties. The bearer chord reaches the ultimate limit state under the uniformly distributed transverse load, which is taken by the cable truss in full. A non-uniform impact is split between the truss and the girder by the condition of compatibility of deformations. The expressions for the axial stiffnesses of the chords, the design clearance values, and the allowable deformations of the roof are given. The work contributes to the development of hybrid building constructions by providing the initial data for the conceptual design stage. It allows to validate structural models and to verify the results of numerical computer analysis.
10.34910/MCE.129.2
624.016
steel beam
steel girder
high strength steel
composite materials
structural design
stiffness
pre-stressed cable systems
tensile membrane roofs
https://engstroy.spbstu.ru/article/2024.129.2/
RAR
RUS
12903-12903
0000-0002-6196-1759
Rasheed
Azad Hameed
Ministry of Water Resources
azad.hameed@muc.edu.iq
Baghdad, Iraq
57783823700
Ahmed
Balqees Abdulwahid
University of Baghdad
Balqees.a@coeng.uobaghdad.edu.iq
Baghdad, Iraq
Dynamic responses of shallow foundations on saturated soft clayey soil under impact loadings
In civil engineering, there are many problems related to the transmission of pressure waves through the soil due to dynamic loads. The objective of this investigation is to research the dynamic soil properties. In industrial applications, these vibrations remain often caused by the impact of weights on the foundation machine. This study investigates how saturated soft clay soil responds to a single impulsive load. Deflectometry via falling weights was conducted to produce single pulse energy by dropping different weights from various elevations. Usually, these dynamic foundations have a greater effect on the surface than various depths of the same foundation. Soil surface responses were studied, then the effects occurring at the depth of the soil surface and causing these responses were studied, which include vertical displacements, velocities, and accelerations. Using the same impact weight (5 kg) at both drop heights (250 mm and 500 mm), the average percentage change in the maximum impact force generated at the contact surface increased by 33 %. This decreased the maximum displacement response of the clay soil model by 25 %, and the maximum displacements increased with increasing operational frequency and dynamic loads.
10.34910/MCE.129.3
624
soft clay soil
impact load
shallow foundations
vertical displacement
https://engstroy.spbstu.ru/article/2024.129.3/
RAR
RUS
12904-12904
57208781021
0000-0002-5364-5473
Bondarev
Dmitrii
CKTI-Vibroseism Ltd.
89523684328@mail.ru
St Petersburg, Russian Federation
Tuned mass damper for reduction seismic and wind loads
Tuned mass dampers (TMDs) are used mainly for reduction of seismic and wind oscillations in high-rise buildings. It is well known that base isolation is ineffective in tall buildings. In general, TMDs can reduce seismic loads in tall building, but it needs a large mass of TMDs. In addition, TMDs cannot reduce vertical oscillations, which can be very destructive due to P-delta effect. This paper presents an engineering solution for mitigation of structural response caused by seismic excitations. The approach of using the upper part of the building as a TMD can significantly reduce horizontal accelerations and stresses in building elements up to 50 % along the entire height. In addition, the proposed TMD can significantly reduce vertical oscillations in a primary building up to 30 % in comparison with building without TMD. This solution can be used in both existing and new buildings. This solution does not require any additional mass and its transportation to the installation site. An optimization criterion for defining optimal TMD’s properties was developed. The criterion is the objective function of maximum difference in accelerations of floors with and without TMD along the entire height. For analytical studies, matrix of stiffness that takes into account bending and sliding motions and dissipation matrix that takes into account damping ratio for soil, TMD constructions and constructions of the building were developed.
10.34910/MCE.129.4
699.841
tuned mass damper
wind load
seismic load
vibration control
optimization
https://engstroy.spbstu.ru/article/2024.129.4/
RAR
RUS
12905-1290
Ahmed
Sahar
Ministry of Sciences and Technology
as.18.48@grad.uotechnology.edu.iq
Baghdad, Iraq
Hameed
Awham M.
University of Technology
awham.m.hameed@uotechnology.edu.iq
Baghdad, Iraq
Al-Adili
A.Sh.
University of Technology
Aqeeladili@hotmail.com
Baghdad, Iraq
Effect of nanosilica on properties of porcelanite aggregate concrete
Lightweight concrete has been used in buildings for centuries, due to its longevity and durability. In recent years, new studies have shed light on additives capable of reducing concrete weight while increasing strength. Nanosilica is one of these additives, which regulate the fundamental calcium-silicate-hydrate (C-S-H) process in water. The addition of nanosilica (NS) particles to concrete improves its density and strength. In this work, we started by creating a reference mixture without additives and another mixture containing a different ratio of nanosilica. Porcelanite was used as a lightweight aggregate. First, the porcelanite aggregate was crushed into pieces of different sizes (6 and 9.5 mm). The results of testing under compression showed that mixes containing 1 wt. %, 1.5 wt. %, and 2 wt. % of nanosilica gave the best results when compared to a reference mix without nanosilica. Porcelanite (rich in SiO2) and nanosilica were utilized to partially substitute cement. A comparison was made with the reference mix (without nanosilica) to figure out the efficiency of using nanosilica in lightweight porcelanite concrete. The highest average compressive strength at a particle size of porcelanite (6 mm) of 18.1 MPa and 15.3 MPa can be obtained at 28 days using 1.5 wt. % and 2 wt. % of nanosilica, with 40.3 % and 18.6 %, respectively. The addition of 1 wt. % of NS, on the other hand, has a negative effect on the compressive strength of 6 mm grain size porcelanite by a factor of not more than 2.3 % at 28 days. Flexural strength of 3.04 MPa can be obtained at 28 days using 1.5 wt. % of NS at a particle size of 6 mm of porcelanite, with percentages of 424.1 %. The flexural strength of porcelanite aggregate concrete increases with a low percentage of various NS. The bulk density decreases when using porcelanite aggregate concrete at 6 mm and 9.5 mm particle sizes with 2 % of nanosilica by 4.84 % and 8.86 %, respectively. Field emission scanning electron microscope (FESEM) test was carried out to study the structure of the fractured nature of the highest compressive strength samples and reference.
10.34910/MCE.129.5
691.5
lightweight concrete
porcelanite aggregate
nanosilica
compressive strength
flexural strength
field emission scanning electron microscope
https://engstroy.spbstu.ru/article/2024.129.5/
RAR
RUS
12906-12906
0000-0003-3997-8009
Ayasrah
Mo'men
Al al-Bayt University
momen_992@yahoo.com
Mafraq city, Jordan
Fattah
Mohammed Y.
University of Technology
myf_1968@yahoo.com
Baghdad, Iraq
Assessment of two nearby interfering strip footings of different embedment depths in saturated cohesive soils
There are instances where foundations are closely spaced, such as around railroad sleepers and foundations close to property lines. In such circumstances, the stress isobars of the separate footings may interact and combine to generate an overlapping stress isobar that affects a wider zone of the foundation soil and alters the individual foundations behavior, which would be different from that of the isolated footings. As a result, an examination of such issues should be conducted by taking into account all the variables that realistically affect the interference behavior of such closely spaced footings. A numerical study is carried out using the finite element program (Midas GTS-NX), and the behavior of closely placed strip footings of different depths embedded in the saturated cohesive soils is investigated under the influence of different factors such as the spacing between footings, the depth of footings, soil undrained shear strength, and the groundwater table. The evaluated ultimate bearing capacity (UBC) and settlements are represented in terms of non-dimensional efficiency factors for UBC: ξL/ξR (Left/Right). It was concluded that when the spacing between footings is increased from S/B = 1 to 2, there would be an increase in the UBC of both footings when Dfr/Dfl increases, then the bearing capacity decreases when S/B is increased to 4. For footings of different embedment depths, when the ground water table is deep (at 4 m depth), the values of UBC ratio ξR increase with S/B while ξL decreases. This is because of various embedment between the two adjacent footings. In all cases, when the ground water table is at the ground surface, lower values in ξL are at Cu = 60 kPa, while the higher values in ξR are found at this strength.
10.34910/MCE.129.6
624
finite elements
nearby footings
cohesive soil
embedment depth
bearing capacity
https://engstroy.spbstu.ru/article/2024.129.6/
RAR
RUS
12907-12907
Hamdy
Hasanien Sameer
University of Babylon
hasanien.hamdy.engh374@student.uobabylon.edu.iq
Babylon, Iraq
Kadhum
Mohammed Mansour
University of Babylon
eng..mohammed.mansour@uobabylon.edu.iq
Babylon, Iraq
Alwash
Nameer A
University of Babylon
nameer_alwash@yahoo.com
Babylon, Iraq
Burning effect on physical characteristics of high-strength lightweight concrete T-beam repaired by SIFCON
The purpose of this research is to investigate the performance of high-strength lightweight cement concrete under extreme high temperature (fire) conditions. Lightweight expanded clay aggregate (LECA) was used as aggregate for the reference mixture. An important difference from previous experiments was that the fire-damaged T-beams were covered with a layer of slurry infiltrated fiber concrete (SIFCON) with 15 and 30 mm thickness at a post-development stage. In addition to the standard tests, this study focused on the effects of the exposure of the beams to a burning flame for 30 min. The temperature distribution inside the T-beam's cross section was measured by installing thermocouples at strategic points. All materials used in this study were analyzed for their physical and chemical properties. Four concrete beam samples were examined in three phases (baseline “control”, fire test, and SIFCON reinforcing). Several parameters, including maximum load capacity and corresponding displacement “deflection”, ductility index, cracking load, initial and secant stiffness, and energy absorption, served as a basis for comparison between the samples. Compared to the damaged samples, the reinforced beams showed significant improvement in the experimental test results conducted in this study. Furthermore, they are as good as or better than the undamaged (reference) T-beams in all parameters except energy absorption. Further research and efforts are needed to resolve this problem.
69
10.34910/MCE.129.7
high-strength lightweight aggregate concrete
fire damaged concrete
LECA
repair material
SIFCON
https://engstroy.spbstu.ru/article/2024.129.7/
RAR
RUS
12908-12908
Mohammed
Shaysh A.
The University of Baghdad
shaysh96@outlook.com
Baghdad, Iraq
Said
AbdulMuttailb I.
The University of Baghdad
dr.abdulmuttalib.i.said@coeng.uobaghdad.edu.iq
Baghdad, Iraq
Concrete beams reinforced with longitudinal and transverse GFRP bars
This research investigated experimentally and numerically the general behavior of six concrete beams reinforced with longitudinal and transverse bars made of Glass Fiber Reinforced Polymer (GFRP) or steel. Six beams were divided into three groups with different variables. The first group consisted of two beams reinforced with GFRP bars in main direction and with steel stirrups. The variable of this group was the spacing between the stirrups. The second group consisted of two beams also reinforced with GFRP bars in the longitudinal direction and with stirrups in the transverse direction. The variable of this group was the same – spacing between the stirrups. As for the third group, it consisted of two beams reinforced with GFRP bars in the longitudinal direction and without stirrups in the transverse direction. The variable of this group was the main reinforcement ratio. The results showed that the beams reinforced with GFRP bars improved their behavior, bending strength and the deflection with different ratios, but had somewhat limited shear resistance when using GFRP stirrups. All the tested beams exhibited linear elastic behavior until failure, with GFRP being more brittle compared to that of ductile steel. The numerical simulation of six beams using ABAQUS software showed good agreement with the experimental data obtained in the laboratory.
10.34910/MCE.129.8
69
GFRP
flexure
deflection
crack
concrete
shear
dowel action
https://engstroy.spbstu.ru/article/2024.129.8/
RAR
RUS
12909-12909
56006941400
0000-0003-3479-1907
Gruzin
Andrey
Omsk State Technical University
polyot-m@mail.ru
Omsk, Russian Federation
Soil information model for prediction the soil properties characteristics
The soil properties characteristics are the object of the current study. Determination of the soil properties characteristics is a complex and responsible engineering and geological task. Reliability of engineering construction and its cost depend on the quality of solution of this task. The article presents the results of the study of the possibility of predicting the soil properties characteristics on the example of determining the sand deformation modulus. Based on the analysis of previous studies of correlation between the soil properties characteristics, the list of independent soil properties characteristics was determined: soil genesis, static normal stress, granulometric composition, initial density and humidity of the soil sample. The main disadvantages of existing methods of predicting the soil properties characteristics were identified. The possibility of using artificial neural network for predicting the soil properties characteristics was determined. The soil deformation modulus was selected as a response (dependent variable). The presence of not only numerical but also classification features among the independent characteristics did not allow predicting the soil properties characteristics within the framework of the classical regression model. A soil information model, based on an artificial neural network, was used to solve this problem because not only continuous quantitative but also discrete classification parameters (genesis) can be used among the independent parameters of the soil information model. Laboratory studies of 655 samples of alluvial sand of the Irtysh River floodplain were performed to confirm the possibility of using the soil information model. 5895 data vectors were obtained, including information on independent and response parameters. A detailed study of two granulometric compositions demonstrated limited possibilities for using known statistical methods for determining the soil properties characteristics. In 9 out of 20 cases, the results of the studies did not follow a normal distribution. The use of the soil information model allowed to solve this problem – the absolute percent error in determining the deformation modulus did not exceed 12.55 % (mean – 5.05 %), the coefficient of determination R2 was at least 0.83 for unloaded sand samples, and at least 0.94 for loaded ones, for all datasets – 0.97. The performed studies confirmed the prospects of using the soil information model for predicting soil properties based on its known characteristics, which reduced the cost of engineering and geological surveys while ensuring the required accuracy of determining the soil characteristics.
10.34910/MCE.129.9
624.131
mechanical properties
prediction
sand
artificial neural network
soil information model
https://engstroy.spbstu.ru/article/2024.129.9/
RAR
RUS
12910-12910
0000-0003-0198-6679
Eshmatov
Bakhtiyor
Almalik Branch, National University of Science and Technology MISiS
ebkh@mail.ru
Almalik, Uzbekistan
S-1676-2017
6507460407
0000-0002-8907-7869
Mirsaidov
Mirziyod
Tashkent Institute of Irrigation and Agricultural Mechanization Engineers
theormir@mail.ru
39, Kori Niyoziy St., Tashkent, Uzbekistan, 100000
6506522453
0000-0001-8114-1187
Abdikarimov
Rustamkhan
Tashkent Financial Institute
rabdikarimov@mail.ru
60A, A.Temur street, Tashkent city, 100000
M-6585-2013
6508103761
0000-0002-1196-8004
Vatin
Nikolai
Peter the Great Saint Petersburg Polytechnic University
vatin@mail.ru
Polytechnicheskay, 29
Buckling of a viscoelastic anisotropic fiber reinforced plate under rapidly increasing shear load
The problem of stability of a viscoelastic anisotropic fiber reinforced plate under the action of a rapidly increasing (dynamic) shear load in a geometrically nonlinear formulation is considered. The mathematical model of the problem is described by a system of nonlinear partial integro-differential equations with singular relaxation kernels. The Bubnov–Galerkin method is used to obtain systems of ordinary nonlinear integro-differential equations. The solution of the system of resolving equations is carried out by a numerical method based on quadrature formulas. To substantiate the accuracy and adequacy of the obtained results, a test problem is solved. A stability criterion for reinforced plates under the action of shear loads is introduced. Depending on various geometric, physical, and mechanical characteristics of the material, the behavior of the reinforced plate is investigated. In particular, it is shown that taking into account the viscoelastic properties of the material leads to a decrease in the critical time, and therefore in the critical force. Depending on various geometric and physical parameters, the difference in critical time values for elastic and viscoelastic plates in some cases is more than 15 %. It is also shown that an increase in the angle of fiber direction in the plates leads to a decrease in the critical time. Among the single-layer reinforced plates, the plate with a fiber direction of 0° is the most resistant to shear loads. An increase in the number of layers in a reinforced plate while maintaining its thickness does not always favorably affect the stability of the plate. In the case of three-layer viscoelastic plates made from KAST-V material with fibers oriented in the direction of 45°/–45°/45°, they are less stable than double-layer plates but more stable than single-layer ones while maintaining equal thicknesses of all three structures.
10.34910/MCE.129.10
69
dynamic stability
viscoelastic anisotropic fiber reinforced plate
system of integro-differential equations
weakly-singular Koltunov–Rzhanitsyn kernel
critical time
https://engstroy.spbstu.ru/article/2024.129.10/