75504
2712-8172
Magazine of Civil Engineering
4
56
2015
1-78
RAR
RUS
3-10
M-6585-2013
6508103761
0000-0002-1196-8004
Peter the Great Saint Petersburg Polytechnic University
Vatin
Nikolai
vatin@mail.ru
Polytechnicheskay, 29
7801686579
0000-0001-7011-8213
Peter the Great Saint Petersburg Polytechnic University
Barabanschikov
Yuri
ugb@mail.ru
Polytechnicheskay, 29
Peter the Great Saint Petersburg Polytechnic University
Komarinskiy
Mikhail
komarin@cef.spbstu.ru
Polytechnicheskay, 29
Peter the Great Saint Petersburg Polytechnic University
Smirnov
Stanislav
smirnovsta@mail.ru
Polytechnicheskay, 29
Modification of the cast concrete mixture by air-entraining agents
The paper investigates the combined effect of superplasticizer based on the naphthalene lignosulfonate and the air-entraining surfactant agent on the fluidity, connectivity and air entrainment of concrete. The air-entraining surfactant agent contributes significantly into air entrainment and reduces the water gain and the mortar separation. It was found that under the introduction of air-entraining surfactant agents in the concrete mixture which contains the superplasticizer, the concrete mobility decreases even though the air-entraining agent is a plasticizer itself. The introduction of 0.1 % air-entraining agent decreases mobility: slump Abrams – 5–6 %, slump flow – 18–22 %. Besides, the effect of increasing the connectivity of the concrete mix is associated with the air entrainment. Regardless of the air-entraining surfactant agent, the superplasticizer reduces water separation, and does not have an air-entraining impact, and virtually has no effect on the air entrainment caused by the addition of the air-entraining agent. With the increasing quantity of the air-entraining surfactant agent in the concrete mix, regardless of the superplasticizer dosage, the amount of the entrained air increases from 3 to 7 %, and water separation is reduced to almost 0. Thus, the synergy of the superplasticizer and the air-entraining agent was negative, but it is possible to observe a positive effect in respect of the concrete mix connectivity.
10.5862/MCE.56.1
complex chemical additive
concrete mix
superplasticizer
air-entraining agent
workability
water gain
mortar separation
air entrainment
concrete additives
https://engstroy.spbstu.ru/article/2015.56.1/
01.pdf
RAR
RUS
11-18
Peter the Great Saint Petersburg Polytechnic University
Loginova
Irina
Iraloginova8@gmail.com
Polytechnicheskay, 29
Peter the Great Saint Petersburg Polytechnic University
Artamonova
Darya
dusia2006@rambler.ru
Polytechnicheskay, 29
Peter the Great Saint Petersburg Polytechnic University
Stolyarov
Oleg
oleg.stolyarov@rambler.ru
Polytechnicheskay, 29
6701751705
0000-0002-7889-1996
Peter the Great Saint Petersburg Polytechnic University
Boris
Melnikov
kafedra@ksm.spbstu.ru
Polytechnicheskay, 29
Effects of structure type on viscoelastic properties of geosynthetics
This work presents a study on tensile properties of geosynthetic materials. There were investigated six samples of geofabrics and geogrids with different structures including woven geotextile fabrics, nonwoven geotextile fabrics, warp-knitted geogrids and extruded geogrid. The study determined tensile properties of geosynthetics including tensile strength, strain at the maximum load and tensile load at a specified strain. The authors carried out creep and relaxation tests. It was found that the structure type significantly affects viscoelastic properties of geosynthetics materials. The article presents some results of numerous tests, which may be used to pre-select geosynthetics materials.
10.5862/MCE.56.2
geotextiles
geogrids
woven fabrics
nonwoven fabrics
mechanical properties
creep
stress relaxation
https://engstroy.spbstu.ru/article/2015.56.2/
02.pdf
RAR
RUS
19-27
Kazan State University of Architecture and Engineering
Popov
Anton
a.o.popov@yandex.ru
Settlement calculation of clay bed reinforced with vertical elements
A distinctive feature of the reinforced pile foundation is that there is no direct contact between the foundation (pile cap) and pile, and the load on the reinforced base is transmitted through the soil. This seemingly minor difference from the pile foundation makes a radical change in the stress-strain state, and hence in the carrying capacity and settlement. In this article on the basis of the previous experimental and theoretical research the author presents a new methodological approach to the calculation of the final settlement of clay soil foundations reinforced with vertical elements, allowing for the effect of the limit state areas.
10.5862/MCE.56.3
bearing capacity
settlement
soil reinforcement
vertical reinforcing element
https://engstroy.spbstu.ru/article/2015.56.3/
03.pdf
RAR
RUS
28-37
Donbas National Academy of Civil Engineering and Architecture
Bondarev
Alexey
bondarev_a_b_rus@mail.ru
Makiyivka, Ukraine
Donbas National Academy of Civil Engineering and Architecture
Yugov
Anatoliy
amyrus@mail.ru
Makiyivka, Ukraine
Evaluation of installation efforts in metal coatings, allowing for assembly process
This article gives an account and analysis of the accuracy of assembly variations in the parameters of the stress-strain state - according to values of assembly (initial) efforts. Deviations are determined by the position of nodes and rods in space relative to their design values. The article considers two technological schemes of the dome cover assembly - from the edge to the center and from the center to the edge. . The accuracy calculation was made with the author's developed computing system "Dimensional analysis of rod structures" . Parameters of the stress-strain state of the dome cover, allowing for the accumulation of assembly deviations, were estimated using the computer complex SCAD. The results of the calculation effort in the shell, taking into account possible assembly deviations, are presented in the form of histograms; and deviations in the nodes and rods are presented in a tabular form. The data on the assembly effort and the deviations are given for individual items. The author suggests constructive solutions for joining rods and installation method for coatings, which are aimed at increasing their load-bearing capacity, longevity and assemblability.
10.5862/MCE.56.4
large-span spatial shells
hinged frame structures
installation effects
assembly deviation
assembly errors
https://engstroy.spbstu.ru/article/2015.56.4/
04.pdf
RAR
RUS
38-44
H-9967-2013
16412815600
0000-0002-8588-3871
National Research University "Moscow Power Engineering Institute"
Kirsanov
Mikhail
mpei2004@yandex.ru
14, Krasnokazarmennaya, 111250 Moscow, Russia
Mathematical model of the truss with hardening elements
In the system of computer mathematics Maple the analytic expression for the deflection of the truss with the added belt stiffness was obtained by the method of induction. There was selected a flat beam model of a truss with uniform vertical loads along the lower belt. Stiffness of the rods was accepted equal. Hardening elements represent horizontal rods and the rack which form the additional belt at the bottom of the truss. Forces in the rods were determined in an analytical form by the method of cutting nodes. The statically indeterminate system, resulting from the introduction of hardening elements, was revealed by the method of forces. Coefficients of canonical equations and the deflection of the mid-span in the lower belt were calculated by Maxwell-Mohr formula. The article presents graphs of the dependence of deflection on dimensions of the truss and a number of panels. The asymptotic properties of these dependencies allow optimizing the construction.
10.5862/MCE.56.5
truss
statically indeterminate system
exact solution
Maple
deflection
https://engstroy.spbstu.ru/article/2015.56.5/
05.pdf
RAR
RUS
45-53
Vologda State University
Utkin
Vladimir
UtkinVoGTU@mail.ru
Vologda, Russia
57191529586
https://orcid.org/0000-0001-7083-7963
Vologda State University
Solovyov
Sergey
ser6sol@yandex.ru
Vologda, Russia
Calculation of the residual bearing capacity of reinforced concrete beams by the rigidity (deflection) criterion
The article proposes the method of calculating the bearing capacity of reinforced concrete beams at the operational stage by the rigidity (deflection) criterion. The methods, which were used in the article, are integral test and probabilistic methods for describing random variables. The author offers a new technique of calculating a deflection limit by a criterion of residual deformations. The article exemplifies the usage of the evidence theory for statistical information processing in the form of a set of intervals. Besides, the paper considers variants of concordance between ultimate and operational loads for different design schemes of reinforced concrete beams.
10.5862/MCE.56.6
bearing capacity
ultimate load
reinforced concrete beam
deflection
rigidity
random variable
confidence interval
https://engstroy.spbstu.ru/article/2015.56.6/
06.pdf
RAR
RUS
54-65
56091980300
0000-0003-3850-424X
Peter the Great St. Petersburg Polytechnic University
Lalin
Vladimir
vllalin@yandex.ru
29 Politechnicheskaya St., St. Petersburg, 195251, Russia
Peter the Great Saint Petersburg Polytechnic University
Zdanchuk
Elizaveta
zelizaveta@yandex.ru
Polytechnicheskay, 29
Peter the Great Saint Petersburg Polytechnic University
Kushova
Darya
dasha_kushova@mail.ru
Polytechnicheskay, 29
Peter the Great St. Petersburg Polytechnic University
Rozin
Leonid
smitu@cef.spbstu.ru
Saint Petersburg, Russia
Variational formulations for non-linear problems with independent rotational degrees of freedom
We consider the geometrically and physically nonlinear theory of elastic rods (Cosserat – Timoshenko rods) and the elastic Cosserat medium. These theories consider independent translational and rotational degrees of freedom. Systems of differential equations for these theories are well known. In this paper we obtain the variational formulation of static problems for these theories. The variational problem was defined as a problem of searching for the stationary points of functionals. The variational functionals are important for the correct formulation of finite element method algorithms for nonlinear problems, as well as for the formulation and solution of stability problems.
10.5862/MCE.56.7
independent rotational degrees of freedom
geometrically exact theory of Cosserat rods
nonlinear Cosserat continuum
https://engstroy.spbstu.ru/article/2015.56.7/
07.pdf