33407
2304-6295
Construction of Unique Buildings and Structures
1
99
2022
1-60
RAR
RUS
9901-9901
0000-0001-7287-1145
Solodilova
Viktoriia Andreevna
Southwest State University
bbty@yandex.ru
50 Let Oktyabrya Street, 94, Kursk, Russia
0000-0003-1951-7299
Dubrakova
Ksenia Olegovna
OBU "Design Institute of Civil Engineering, planning and development of cities and towns "Kurskgrazhdanproekt
Dko1988@yandex.ru
Dimitrova street,96/1, Kursk, Russia
7005346094
0000-0003-4261-9840
Bulgakov
Alexey Grigor’evich
Southwest State University
agi.bulgakov@gmail.com
50 let October St. 94, 305040 Kursk, Russia
A-7827-2017
56662851300
0000-0001-8407-8144
Erofeev
Vladimir Trofimovich
Ogarev Mordovia State University
yerofeevvt@mail.ru
Bolshevistskaya St., 68, Saransk, Russian Federation
0000-0001-7157-2143
Otto, J.
Otto, Jens
Technical University of Dresden
jens.otto@tu-dresden.de
Mommsen Str. 10, 01062 Dresden, Germany
Fire resistance of statically indeterminate steel systems
The object of research is a single-span metal frame. Since the fire resistance of metal-bearing structures is insignificant, this is because at temperatures above 400 °C for steels and more than 200 °C for aluminium alloys, significant development of plastic deformations under constant load (creep) begins to manifest itself. The purpose of this work is to conduct research aimed at studying various emergency impacts, in particular, the impacts associated with heating during a fire and its effect on the stability of both individual elements and the entire structural system. To meet the new requirements of Federal Law "Technical Regulations on the safety of buildings and structures". To identify the influence of the heating temperature of the gas medium on the mechanical characteristics of steel structures by obtaining data from the accepted regularity and constructing a trend line and by the method of displacements, taking into account kinematic definiteness, to investigate the effect of temperature at uniform heating during a fire on the value of critical parameters of a single-span frame. By solving some problems that arose during the study, we can say about the necessity to improve steel structures to prevent irreversible consequences during an emergency. The research's main results are to identify the relationship between the temperature of the medium on the mechanical characteristics of steel structures.
10.4123/CUBS.99.1
69
Fire resistance
steel structures
statically undetectable systems
emergency
defects
https://unistroy.spbstu.ru/article/2022.100.1/
RAR
RUS
9902-9902
6506150284
0000-0003-1139-3164
Sainov
Mikhail Petrovich
Moscow State University of Civil Engineering
mp_sainov@mail.ru
Moscow, Russian Federation
57204501403
0000-0003-4277-7128
Soroka
Vladislav Borisovich
Moscow State University of Civil Engineering
Moscow, Russian Federation
J-8425-2019
57194142918
0000-0002-1151-0853
Gunasekaran
Murali
SASTRA Deemed University
murali@civil.sasta.edu
Thanjavur, India
Combination of rockfill dam reinforced concrete face and seepage control wall in the foundation: stress-strain state
Introduction. Construction of reinforced concrete face rockfill dams on soil foundations requires solving the problem of arranging a safe diagram of conjugation between a dam reinforced concrete face and a seepage control structure in the foundation. The object of research is the Miaojiaba dam, 111 m high (Gansu, China), which in the channel part rests on a huge layer of soil base, and in the side sections is located on rocks. Materials and Methods. Stress-strain state (SSS) of a reinforced concrete face (CF) and a cutoff wall (COW) of the considered dam was studied with the aid of numerical modeling. The study was conducted in 2D and 3D formulations. Finite elements with high degree of approximation inside the elements are to be used for modeling of thin-wall structures. Results. By the results of numerical modeling the CF and COW are subject to complicated deformations and are in a complicated stress state. It is characterized by presence of considerable compressive forces both in the face and in the wall. Nevertheless, compressive forces do not exceed the limit compressive strength of concrete. Tensile stresses are more dangerous for strength of seepage control structures. In the face the tensile stresses appear in the zone of conjugation with rock foundation. COW is subject to tension in the zone of rest on a stiff concrete apron. Besides, COW separates from rock sides. All this creates the danger of failure of seepage control protection tightness. Conclusions. At designing rockfill dams with combination of a reinforced concrete face and a seepage control wall a special attention should be paid to spatial conditions of these elements’ performance. This will help in finding the zone of appearance of dangerous stresses, which are not seen at solving a 2D problem. However, it is evident that conjugation of CF with COW with the aid of a stiff concrete apron is not a safe solution.
10.4123/CUBS.99.2
69
Stress-strain state
rockfill dam
concrete face
soil foundation
strain
cut-off wall
seepage-control wall
https://unistroy.spbstu.ru/article/2022.100.2/
9902.pdf
RAR
RUS
9903-9903
AAE-3259-2020
56296687300
0000-0002-2299-3096
Rybakov
Vladimir Alexandrovich
Peter the Great St. Petersburg Polytechnic University
fishermanoff@mail.ru
St. Petersburg, Russian Federation
57216911588
0000-0003-2067-5585
Jos
Vladislav Andreevich
Technische Universität Dresden
jos_vlad@mail.ru
Dresden, Germany
Stress State of Г-Shaped Thin-Walled Rod Joints in Bending Torsion
The paper is devoted to the study of constrained torsion in joints of flat thin-walled rod systems. The goal of the work is to analyze the stress state of finite stiffness joints made of two thin-walled open-profile rods with different parameters, which are under conditions of bending torsion (The object of research), and to determine the corresponding rotation coefficient. Method. The main research method in the paper is the finite element method. The software program ABAQUS is used in order to design and calculate 1-D and 3-D finite element models of various joints and structures made of thin-walled profiles. Results. The areas of application of previously known hypotheses were determined: the hypothesis of A.R. Tusnin; the hypothesis of A.S. Gorodetsky and others. By the design and calculations of 3-D finite element models, the behaviour of the bimoment transmission was investigated in the joints made of thin-walled profiles: with different stiffness; connected at different angles; taking into account structural elements (gusset plate, corners, bolted connections). The recommended values of the “coefficient of the cross-sectional axis rotation” in the joints made of thin-walled profiles connected at the angle of 90˚ were determined. It is shown the existence of an angle between the profiles of the Г-shaped connection, at which the rotation coefficient is equal to zero, which in turn demonstrates the absence of the bimoment transmission in the joint.
10.4123/CUBS.99.3
69
Lightweight gauge steel structures
Bending torsion
Plane frames
Thin-wall rods
Rigid joint
Bimoment
Warping
Stresses
https://unistroy.spbstu.ru/article/2022.100.3/
9903_1.pdf
RAR
RUS
9904-9904
H-9967-2013
16412815600
0000-0002-8588-3871
Kirsanov
Mikhail Nikolaevich
National Research University Moscow Power Engineering Institute
mpei2004@yandex.ru
Moscow, Russian Federation
Model of a spatial dome cover. Deformations and oscillation frequency
The object of research. A new scheme of a statically determinate spatial truss is considered. The design has a hexagonal dome resting on two belts. The belts are supported by vertical racks. Two corner supports have spherical and cylindrical hinges. The outer support contra consists of 6n horizontal rods, the inner one consists of 6(n-1) rods. The contours are connected by skews. Formulas are derived for the deflection of the vertex and the angular hinge depending on n. The upper and lower analytical estimates of the first frequency of natural oscillations of the structure are found. Method. Calculation of the forces in the rods is carried out by cutting out the nodes from the solution of the system of equilibrium equations for all nodes in the projection on the coordinate axes. To derive formulas for the dependence of breakdowns, forces, and the frequency of free oscillations, an inductive generalization of the sequence of solutions for structures with a different number of panels is used. The structural stiffness matrix and deflection are calculated using the Maxwell - Mohr formula in analytical form. To find estimates of the lowest frequency of vibrations of nodes endowed with masses, the Dunkerley and Rayleigh methods are used. Results. The vertical load distributed over the nodes and the concentrated load applied to the top are considered. Formulas for the forces in the characteristic bars of the structure are derived. A picture of the distribution of forces throughout the structure is presented. The resulting formulas for the deflection and frequency estimates have a compact form. The upper estimate of the first oscillation frequency of nodes under the assumption of vertical displacements of points has fairly high accuracy. The analytical solution is compared with the lowest oscillation frequency obtained numerically. All analytical transformations are performed in the Maple symbolic mathematics system. Some asymptotics of solutions is found.
10.4123/CUBS.99.4
69
Spatial truss
Vibrations frequency
Maple
Analytical solution
Deflection
Induction
Rayleigh method
Dunkerley method
Asymptotics
Maxwell-Mohr formula
https://unistroy.spbstu.ru/article/2022.100.4/