Vol. 25, Number 3, 2019

Igor Garanzha a, Diana Sakhibgareeva b, Irina Tanasoglo c
Deformed State of Flat Steel and Steel-Reinforced Concrete Frames when Working together with a Ground Base
a People’s Friendship University of Russia (RUDN), b Moscow State National Research University of Civil Engineering, c Donbas National Academy of Civil Engineering and Architecture
Abstract. The article presents the results of analysis of the deformed state of single-span flat steel and steel-reinforced concrete frames when working together with ground bases that lie on the territory of Moscow and the Moscow region. The forces in the frame under study were determined by the finite element method implemented in SCAD. The main goal of the work is a comparative analysis of modeling soil foundations with different sections of frame elements and types of bases. The obtained results allow us to evaluate the feasibility of using a steel-reinforced concrete cross-section for frame elements according to the criterion of deformability, as well as to analyze the interaction of the rotation of foundations and movements of characteristic points of the frame.
Keywords: deformed state, steel-reinforced concrete frames, joint work with the soil base, the model of the soil base, Winkler theory, Pasternak theory, clay soil, sandy soil.

Vadim Gubanov, Andrey Mironov, Yana Zikii, Alina Pchelenko
Modeling of Deformations of a Residential Brick Building in Conditions of Uneven Precipitation
Donbas National Academy of Civil Engineering and Architecture
Abstract. This paper includes the results concerning studies of numerical models of a brick residential building. Description for creating an analytical volumetric model in the LIRA-SAPR 2013 is given. The features of modeling uneven settlement of a subsoil base caused in consequence of located building on first and second group of undermining territory are shown. The calculation of the displacement of the base as a function of the length of the building and the radius of curvature of displacement trough was made. The influence of uneven settlements on the stress-strain state of the bearing walls of a building are describe. The calculation of the width of the cracks opening was carried out using data on the location and magnitude of the settlement in the walls of the building. As a result, the analysis depending on the level part on the VAT building and conditional precipitation of the building on the percentage of affected cracks load-bearing walls of a brick building has been made.
Keywords: building, refurbishment, bricks, 3D FEM elements, numerical modeling, foundation, uneven settlement.

Vladimir Mushchanov, Alexander Demidov, Anatoly Orzhekhovsky
Stress-Strain State of Inelastic Composite Open Shell
Donbas National Academy of Civil Engineering and Architecture
Abstract. The article presents a numerical calculation of an inelastic open-ended composite shell consisting of a cylindrical and conical part by the method of successive approximations based on the method of elastic solutions. The problem of elasticity in each approximation is solved by a difference method based on the variational equation of J. Lagrange in displacements of points of the median surface. In this case, the matrix of the system of equations does not change from approximation to approximation. Only the right-hand parts, which depend on plastic deformations, are changed. First, the statement of the problem is given: a circular open composite shell is considered, consisting of a cylindrical and conical part with hingedly fixed meridional edges and rigidly embedded edges in the circumferential direction under uniformly distributed load acting normal to the middle surface. Boundary conditions are formulated. The validity of using shell symmetry is proved. The convergence of the solution of the elastic problem is established by double thickening of the grid. The moment of appearance of the first plastic deformations in the most loaded node of the grid area is established. The elastic-plastic state of this shell is determined by the elastic solutions method: the field of intensity of tangent stresses along the thickness of the shell over the entire grid area is specified; the field of deflections of points of the middle surface over the entire grid area is given in tabular form and in the form of volumetric and flat graphs.
Keywords: open composite shell, variation-difference method, boundary conditions, intensity of tangential stresses.

Andrey Mironov, Vladimir Anischenkov, Alexander Volchkov
Stress-Strain State in a Pipe-Concrete Element of a Frame Unit Using I-Beam Crossbars
Donbas National Academy of Civil Engineering and Architecture
Abstract. This article discusses the interface node of a pipe-concrete column of circular cross section with a diameter of 220 mm. and a thick metal wall of 7 mm, the length of the column fragment 1050 mm. The pipe is filled with concrete grade B15. As crossbars, a steel beam of an I-section (20B1) 1100 mm long is considered. The joining of the crossbars to the column is provided by two horizontal and 4 vertical overlays 5 mm thick. by welding. In the LIRA-SAPR 2017 software package, a model of this unit was created and the maximum normal stresses at the joints of the junction of the crossbar to the column were determined. The study was conducted on two models: a model with concrete and pipe working together; а model with concrete slipping inside a steel pipe. That allowed determining the efficiency of this node..
Keywords: pipe-concrete column mating unit, longitudinal force, pipe-concrete element, joint work of concrete core and steel shell, concentration of materials, concentration of maximum stresses at joints, calculation of normal stresses, zones with the highest normal stresses.