75504
2712-8172
Magazine of Civil Engineering
17
4
2024
1-141
RAR
RUS
12801-12801
0000-0003-1304-0303
University of Baghdad
Karkush
Mahdi
mahdi_karkush@coeng.uobaghdad.edu.iq
Baghdad, Iraq
0000-0003-1594-3979
University of Baghdad
Almurshedi
Alaa
a.salman1001@coeng.uobaghdad.edu.iq
Baghdad, Iraq
University of Baghdad
AlSaadi
Karrar
karrar.jawad2001d@coeng.uobaghdad.edu.iq
Baghdad, Iraq
University of Kufa
Al-Salakh
Ahmed
ahmedm.alsalakh@uokufa.edu.iq
Kufa, Iraq
Behavior of partially connected piled raft foundation under seismic loading
A partially connected piled raft foundation is a new modification for the fully connected or disconnected piled raft foundation. The characteristics of the connected piles could transfer loads from the superstructure to the underlying soils. The disconnected piled raft foundation has an effective advantage for reducing the dynamic motion that is transmitted to the high-rise superstructures. However, the dynamic behavior of the partially connected piled raft foundation system under a strong earthquake in medium sand soil has not been thoroughly understood. In this study, the effect of the distribution of piles patterns, number of connected piles (CP), and number of disconnected piles (DP) through a series of seismic experimental model tests have been investigated. These tests were performed with 1, 4, 5, and 9 piles under different static loads. Vertical and horizontal displacements, acceleration, and variation of bending moment of soil and piles are monitored through the experimental tests. The results showed that increasing the number of CP compared with DP contributed to an effective way to reduce the horizontal displacement of the piled raft foundation system. The advantage of DP in resisting seismic loading appears when the number of DP is more than the number of CP. Due to the structural connection of the raft-pile-soil system, the CP was subjected to high values of the seismic acceleration and bending moment. The reduction in the bending moment of DP within the partially connected piles group depended on the number of CP and increasing the thickness of the cushion layer.
10.34910/MCE.128.1
624
partially connected piled raft
disconnected piled raft
seismic loading
piled-raft
cushion layer
https://engstroy.spbstu.ru/article/2024.128.1/
RAR
RUS
12802-12802
57194112309
0000-0001-6184-2365
Vyatka State University
Tyukalov
Yury
yutvgu@mail.ru
The beam finite element with five nodal degrees of freedom
The article presents comparative calculations of reinforced concrete beams using two types of beam finite elements: with three and five nodal degrees of freedom. Calculations were performed both taking into account the concrete and reinforcement physical nonlinearity, and without taking it into account. The expressions for stiffness matrix elements and the load vector were obtained for the finite element with five nodal degrees of freedom. Calculations taking into account physical nonlinearity were performed using the variable elasticity parameters method. As a structure for comparing solutions obtained by the two types of finite elements, a single-span clamped horizontal and inclined reinforced concrete beam were used. The accuracy of calculating beam axis deformations and curvature depending on the number and type of finite elements was assessed. It was shown that when performing linear calculations, bending moments, longitudinal forces and displacements do not depend on the number of finite elements with five degrees of freedom into which the beam had been divided. When solving physically nonlinear problems, if we refine the finite element mesh, the solutions obtained for elements with three degrees of freedom tend to the solutions obtained for a smaller number of elements with five degrees of freedom. The proposed beam finite element with five nodal degrees of freedom makes it possible to determine more accurately the axis curvature and deformation, which is especially important when solving physically nonlinear problems.
10.34910/MCE.128.2
624.04
finite element
five degrees of freedom
reinforced concrete beam
physical nonlinearity
deformation
axis curvature
failure load
https://engstroy.spbstu.ru/article/2024.128.2/
RAR
RUS
12803-12803
PI Georekonstruktsiya
Vasenin
Vladislav
vavasenin@mail.ru
St. Petersburg, Russian Federation
Peter the Great Saint Petersburg Polytechnic University
Sabri
Mohanad Muaya
mohanad.m.sabri@gmail.com
Polytechnicheskay, 29
Compressible soil thickness and settlement prediction using elastoviscoplastic models: a comprehensive method
The paper is dedicated to developing a comprehensive analysis method of the criteria for defining the compressible thickness critical for estimating long-term settlements in buildings and structures situated on soft soils, focusing on their creep behavior. This study introduces an engineering method grounded on the criterion of soil's undrained condition within the mass, considering both elastic and residual deformations through equivalent creep deformations. Unlike previous methodologies, the proposed method facilitates the assessment of long-term settlements by incorporating creep effects over time, employing undrained shear strength for both normally consolidated and overconsolidated soils. The method enables settlement calculations based on static-sounding data, enhancing predictions' accuracy and reliability. This research endeavors to broaden the application of numerical and analytical calculations in real-world practices, employing elastoviscoplastic soil models to design structures on weak foundations.
10.34910/MCE.128.3
624
long-term settlements
soft soils
creep behavior
undrained shear strength
numerical analysis
elastoviscoplastic models
structural foundation design
https://engstroy.spbstu.ru/article/2024.128.3/
RAR
RUS
12804-12804
0000-0003-2104-6457
University of Anbar
Alani
Ahmed Anees
ahmed.anees@uoanbar.edu.iq
Ramadi, Iraq
Lightweight concrete containing recycled aggregates
This study investigated the replacement of fine concrete aggregates with recycled aggregate. The results showed that the effect of recycled aggregate, so that, replacing 25, 50, 75 and 100 % of natural aggregate led to an 8, 23, 15 and 11 %, respectively, increase in the compressive strength of lightweight concrete samples. Based on these results, a microstructural analysis of the contact zone of the concrete using various types of aggregate was conducted. The shrinkage and expansion development of samples containing recycled aggregate formed from demolished waste differed from that of ordinary concrete, and the findings over 90 days indicated the impact of the substitution percentage in the recycled aggregates contained in the mixture. When 100 % fine natural aggregate was replaced with recycled aggregate, expansion increased by 15 % at 14 days and shrinkage increased by 45 % at 90 days as compared to references. Cement hydration in concrete mixes using different types of aggregates has been investigated by using an X-ray diffraction. The results showed that the sample without recycled aggregate from demolition waste LW-1 contained the maximum amount of C3S and C2S compared to the sample with recycled aggregate from demolition waste LW-5, which can harden when interacting with water. The concrete samples used to evaluate the abrasion resistance were first cured for 28 days. The results revealed that the abrasion Δh values for samples containing recycled aggregate were lower than that for the reference samples.
10.34910/MCE.128.4
622
construction waste
recycled aggregate
green composites
lightweight concrete
https://engstroy.spbstu.ru/article/2024.128.4/
RAR
RUS
12805-12805
57208318410
0000-0002-8615-390X
Saint-Petersburg Mining University
Iovlev
Gregorii
gregoriiovlev@gmail.com
St. Petersburg, Russian Federation
Saint-Petersburg Mining University
Belov
Nikita
nikita_belov23@mail.ru
St.Petersburg, Russian Federation
6507413558
0000-0001-9586-8379
Saint-Petersburg Mining University
Zileev
Aleksandr
Zileev_AG@pers.spmi.ru
St. Petersburg, Russian Federation
Numerical prediction of crack formation in historic masonry buildings
This article investigated mechanical behavior of the masonry of historic buildings. It was assumed that reliable cracking processes can be obtained by modeling masonry as a continuous medium and using the Jointed Masonry Model (JMM). The paper gives an analytical review of JMM, identifying the input parameters required for its use. Laboratory tests of brick blocks and mortar for uniaxial compression were carried out and the results of these tests are presented. It is proposed to use the triaxial compression test methodology for rocks for cylindrical samples drilled from bricks. Based on the obtained laboratory data, a method for obtaining input parameters for JMM was proposed. To verify the obtained input parameters of JMM, the construction of a numerical model to predict the stress-strain state of historic masonry buildings was proposed. As an example, old workshop buildings located in the area near St. Petersburg were considered. The results of numerical calculations were compared with the results of building facades surveys for the presence of cracks and opening widths in them. It was found that the zones of the greatest shear deformations were formed mainly in the corners of window and door openings, mainly in the right and left parts of the model. Their position had a qualitative convergence with the results of surveys. The process of formation and qualitative change of zones of limiting compressive and tensile stresses that were formed in the walls of buildings was analyzed using different sets of input parameters of JMM. The influence of dilatancy effects on the stress-strain state was also considered. The study found that a reliable description of the mechanical condition of historic masonry can be obtained using JMM, whose input parameters should be based on the results of laboratory tests. The conducted work showed that along with classical methods of surveys it was possible to use methods of numerical modeling to predict areas where crack propagation occur for historic masonry buildings.
10.34910/MCE.128.5
693.22
constitutive modelling
masonry
brick
compression testing
numerical methods
PLAXIS
mortar
cracks
https://engstroy.spbstu.ru/article/2024.128.5/
RAR
RUS
12806-12806
University of Baghdad
Al-Kabi
Wafaa Hussein
fhussein555@gmail.com
Baghdad, Iraq
University of Baghdad
Awad
Hadeel Khalid
hadeel.kalid@coeng.uobaghdad.edu.iq
Baghdad, Iraq
Fire flame effect on some properties of hybrid fiber reinforced LECA lightweight self-compacting concrete
This research aims to produce lightweight self-compacting concrete (LWSCC) using lightweight expanded clay aggregate (LECA) as coarse aggregate. The additional aim is to study the influence of steel fiber and hybrid fibers (steel and polypropylene (PP)) on the properties of LWSCC in fresh and hardened state. Furthermore, compressive, tensile, and flexural strengths of LWSCC specimens (with and without fibers) are tested after being subjected to the fire exposure. In this study, four LWSCC mixtures with different fiber percentages (0 % fiber, 1 % steel, 0.75 % steel + 0.25 % PP, and 0.5 % steel + 0.5 % PP) are prepared and tested. The specimens were burned at temperatures 25, 300, 400, and 600 °C. The results show that all mixtures have excellent resistance to segregation and high ability to filling and passing. The presence of fibers slightly reduced the workability of LWSCC. The mechanical properties of LWSSC decrease with increasing temperature. The results show that mixtures containing fibers have good mechanical qualities and spalling resistance compared to mixtures without fibers when exposed to fire.
10.34910/MCE.128.6
691
lightweight self-compacting concrete
LECA
fire flame
steel fiber
polypropylene fiber
hybrid fiber
https://engstroy.spbstu.ru/article/2024.128.6/
RAR
RUS
12807-12807
University of Anbar
Hasan
Eanas
ean20e1010@uoanbar.edu.iq
Ramadi, Iraq
56184497100
0000-0001-6180-8837
University of Anbar
Al-Sharrad
Muayad
muayad.alsharrad@uoanbar.edu.iq
Ramadi, Iraq
Suitability of earthen materials for rammed earth in arid region
This study investigated the suitability of two engineered earthen materials manufactured by mixing different proportions of sand, silt, and clay for rammed earth constructions under dry conditions. The first mix contained 30 % fine material, whereas the second mix contained 50 % fine material. Test specimens were prepared by static compaction to 4.5, 25, 50, and 100 MPa, equilibrated at relative humidity values of RH = 35 % and RH = 55 % and tested in the lab to characterize plasticity, mechanical, hydric, and thermal behavior. The materials showed a drying shrinkage of no more than 4 %, depending on the initial water content and the unit weight of the material. The results indicated a remarkable increase in materials elastic stiffness and strength of 50 % to 120 % and 10 % to 70 %, respectively, with increasing dry unit weight or compaction energy. The increase in soil suction led to a profound improvement in stiffness and strength, owing to an increase in capillary bonding. In addition, the increase in finer content from 30 % to 50 % significantly enhanced the mechanical behavior. If a minimum compressive strength of 2 MPa is considered, then compacting the earthen material to 50 MPa or greater would provide sufficient strength under the operational humidity RH=55 %. For the mix with 50 % finer content, a compressive strength of almost 5.75 MPa was achieved when the material was compacted to 100 MPa and equalized to RH = 55 %. As relative humidity increased, materials strength decreased where the amount of reduction was found to be inversely proportional to the compaction level and the maximum dry unit weight. The dynamic adsorption behavior was, largely, independent of the amount of compaction energy or finer content. The dynamic adsorption test indicated that the tested materials exchange a considerable amount of moisture with the atmosphere. Compared to traditional brick and concrete blocks, the materials showed good insulation characteristics. It was observed that the increase in finer content yielded slightly higher thermal conductivity values. Overall, the engineered material examined in this work can be potentially used for rammed earth under dry conditions.
10.34910/MCE.128.7
624
earthen materials
rammed earth
sustainable buildings
dynamic adsorption
https://engstroy.spbstu.ru/article/2024.128.7/
RAR
RUS
12808-12808
0000-0003-3087-0333
University of Kufa
Shabbar
Rana
rana.shubber@uokufa.edu.iq
Al Najaf, Iraq
0000-0001-6244-7965
University of Kufa
Alasadi
Layth Abdulrasool
laitha.alasadi@uokufa.edu.iq
Al Najaf, Iraq
University of Kufa
Taher
Jaber Kadhim
Najaf, Iraq
Influence of silica fume addition on enhancing the autoclaved aerated concrete properties
The demand for lightweight concrete has increased because of its low density, fire resistance and good thermal insulation. Autoclaved aerated concrete (AAC) is the combination of cement, fine-grained sand, lime and water with aluminium powder. This study aims to investigate the influence of adding silica fume (SF) on improving the properties of AAC. The response was studied in terms of testing the mechanical and physical properties including compressive, splitting tensile, flexural strength, density, porosity and coefficient of water absorption. Different mixes have been proposed by incorporating the SF with contents of 10 %, 20 % and 30 % by cement weight, which is compared with the AAC sample that is used in practical applications. The results indicated that there was a significant improvement in the compressive and flexural strength of AAC, which increased by six and three times, respectively, when 30 % of SF was used with an acceptable dry density. Furthermore, the microstructural analysis revealed that SF had a positive effect on the development of calcium silicate hydrate and it can be used in AAC masonry block productions.
10.34910/MCE.128.8
69
autoclaved aerated concrete
modified AAC mix
waste material
water absorption coefficient
https://engstroy.spbstu.ru/article/2024.128.8/
RAR
RUS
12809-12809
Kazan State University of Architecture and Engineering
Vdovin
Yevgeniy
vdovin007@mail.ru
JSC "Alekseevskdorstroy"
Bulanov
Pavel
pavel.bulanov1991@yandex.ru
https://orcid.org/0000-0001-9680-6698
Kazan State University of Architecture and Engineering
Stroganov
Victor
svf08@mail.ru
Kazan, Russia
55530988100
Kazan (Volga region) Federal University
Morozov
Vladimir
Vladimir.Morozov@kpfu.ru
Kazan, Russian Federation
Structure of clay minerals of road soil-cement during complex modification
Previously obtained positive results of studies of physical, mechanical, technological and operational properties of road soil-cement at their complex multifunctional modification with organosilicon compounds and polycarboxylate superplasticizers have shown the effectiveness of the use of strengthened soils in the construction of roads. However, the influence of complex modification on changes in the structure of clay minerals of strengthened soils in road construction remains insufficiently studied. Using X-ray phase analysis, comprehensive studies of the structure of modified clay minerals were carried out to reveal intercalation processes and changes in the size of their particles as a result of splitting processes. Chemical structure of the studied modifiers, nature of their interaction with clay minerals and organomineral bonds were confirmed using IR spectroscopy. The combined influence of modifying effect of dodecyltriethoxysilane and polycarboxylate ester on kaolinite and montmorillonite clays was established, which led to the manifestation of synergistic mechanism at strengthening of clay soils. During the modification, a multifunctional effect was noted, characterized by an increase of integral intensity of diffraction maxima on the diffraction patterns of modified clay soils, associated with an increase of interplanar distances in their structure as a result of intercalation processes. The positive effect of complex modification of clays is associated with splitting and reduction of mineral particle sizes. It has been established that the consequence of complex modification is chemical interaction (chemisorption) with the formation of organosilane bonds, which provide increased efficiency in strengthening of clay soils in road construction.
10.34910/MCE.128.9
625.068.2
kaolinite
montmorillonite
dodecyltriethoxysilane
complex modification
polycarboxylate ester
intercalation
splitting
chemisorption
soil-cement
https://engstroy.spbstu.ru/article/2024.128.9/
RAR
RUS
12810-12810
55023460600
0000-0001-7933-3710
Siberian Federal University
Kudryavtsev
Ilya
kudrilya@rambler.ru
Krasnoyarsk, Russian Federation
Siberian Federal University
Ivanov
Viktor
pi-prm@mail.ru
Krasnoyarsk, Russian Federation
Siberian Federal University
Rabetskaya
Olga
olga_rabez@mail.ru
Krasnoyarsk, Russian Federation
Siberian Federal University
Mityaev
Alexander
aemit@mail.ru
Krasnoyarsk, Russian Federation
Providing free vibrations and stability of a multi-span beam under temperature changes by selecting the support system
This study presents a newly developed method for reasonable selection of boundary conditions and number of pinned intermediate supports for a straight multi-span beam. This method might help to obtain the required values of the first frequency of free vibrations and the critical load from the action of axial force, resulting from the changing the beam temperature. The method is based on known concepts of beam vibration and stability theories and uses support coefficients as a criterion for selecting the appropriate support system for a multi-span beam. These coefficients are obtained by solving the corresponding differential equations of the dynamic behavior of the beam and are determined only by the support conditions. Comparative calculations of the straight pipeline using the developed and finite element methods for beam and shell models were carried out, which showed good convergence. Normalization of the values of the support coefficients allowed to combine both conditions, for the first natural vibration frequency and the first critical force, and express it as a single criterion for the selection of the support system. The selection of the support system is shown as three general methods of fixing multi-beam beams with a constant span length. This approach can be applied to any straight beams and support conditions for which support coefficient values are known. To this end, a general algorithm for selecting a support system with known support coefficients and requirements for their normalization is given. The results obtained can be used in the calculation and design of any multi-span beam structures to control the values of their free vibration frequencies and stability by selecting an appropriate support system during the engineering design process.
10.34910/MCE.128.10
624.07
Euler–Bernoulli beam theory
multi-span beam
periodic structures
temperature
axial compression
free vibration
structural design
buckling
transverse oscillation
topology optimization
finite element method
pipeline
https://engstroy.spbstu.ru/article/2024.128.10/