Magazine of Civil Engineering, No.4(56), 2015
Strength of materials. Structural mechanics
MATERIALS 
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N.I. Vatin, Yu.G. Barabanshchikov, M.V. Komarinskiy, S.I. Smirnov
The paper investigates the combined effect of
superplasticizer based on the naphthalene lignosulfonate and the airentraining
surfactant agent on the fluidity, connectivity and air entrainment of concrete.
The airentraining surfactant agent contributes significantly into air
entrainment and reduces the water gain and the mortar separation. It was found that under the introduction of airentraining
surfactant agents in the concrete mixture which contains the superplasticizer, the
concrete mobility decreases even though the airentraining agent is a
plasticizer itself. 


I.I. Loginova, D.A. Artamonova, O.N. Stolyarov, B.E. Melnikov
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, warpknitted 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. 

CALCULATIONS  

A.O. Popov
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 stressstrain state, and hence in the carrying capacity and settlement. 


A.B. Bondarev, A. Yugov
This article gives an account and analysis of the
accuracy of assembly variations in the parameters of the stressstrain 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. 


M.N. Kirsanov
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. 

METHODS  
V.S. Utkin, S.A. Solovyov
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. 

ANALYSIS  

V.V. Lalin, E.V. Zdanchuk, D.A. Kushova, L.A. Rozin
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. 