33407 2304-6295 Construction of Unique Buildings and Structures 3 96 2021 1-60
RAR RUS 9601-9601 57219014392 0000-0003-3675-5870 Peter the Great St. Petersburg Polytechnic University Baranov Aleksey Olegovich aleksey.o.baranov@yandex.ru
St. Petersburg, Russian Federation
 0000-0002-9165-7168 Peter the Great St. Petersburg Polytechnic University Zorina Evgeniya Alekseevna
St. Petersburg, Russian Federation
 0000-0001-7204-027X Peter the Great St. Petersburg Polytechnic University Kirian Ivan Valerevich
St. Petersburg, Russian Federation
 Mechanical Characteristics of High-Strength Concrete with Fly Ash and Silica Fume at Elevated Temperatures: The Influence of Heating Duration The object of research. High-strength concrete containing a multicomponent additive MB10-50C. The mineral part of the additive is represented by industrial by-products - silica fume and fly ash, and the organic part includes a superplasticizer of the C-3 grade. The subject of the study is the characteristics of the mechanical properties (compressive and splitting tensile strength, modulus of elasticity, Poisson's ratio, limiting deformations) of high-strength concrete after a short- and long-term exposure to elevated temperatures up to 400°C. Method. The high-strength concrete was heated in electric furnaces, and the properties were evaluated based on the residual characteristics after the samples cooled down. The characteristics of the properties of concrete are determined according to the national standards of the Russian Federation. Results. Heating of high-strength concrete at temperatures of 90 and 200°C caused an increase in the residual compressive strength by an average of 5 and 10%, respectively. Compressive strength after prolonged heating at 300 and 400°C decreased and accounted for 90 and 70% of the initial values, respectively. Prolonged heating up to 200°C did not lead to significant changes in the splitting tensile strength, but the splitting tensile strength decrease by about 30 and 70% at heating up to 300°C and 400°C, respectively. Values of the initial elastic modulus and Poisson's ratio after heating at 90-400°C only decreased, while the dependence of the characteristics on the value of the heating temperature is linear. Heating of high-strength concrete at 200-400°C increased the ultimate longitudinal strain by 1.25-1.69 times and the ultimate transverse strain by 2-3.87 times. 10.4123/CUBS.96.1 69 High strength concrete High temperature Compressive strength Tensile strength Elastic modulus Stress-strain curves Fly ash Silica fume https://unistroy.spbstu.ru/article/2021.96.1/
RAR RUS 9602-9602 H-9967-2013 16412815600 0000-0002-8588-3871 National Research University Moscow Power Engineering Institute Kirsanov Mikhail Nikolaevich mpei2004@yandex.ru
Moscow, Russian Federation
 0000-0002-7159-4649 Moscow Power Engineering Institute Khromatov Vasiliy Efimovich KhromatovVY@mpei.ru
Moscow, Russian Federation
 Deformation of the Transmission Towers: Analytical Solution The object of the study is a spatial model of a statically definable power line support truss. The four-sided truss has a cross-shaped lattice and a pyramidal extension at the base. In the upper part of the truss, there are consoles for attaching the carrier cables. The corner nodes in the base are attached to the ground by one spherical joint, a cylindrical joint, and two vertical posts. Two types of loads are considered: a horizontal load evenly distributed over the nodes of one face (wind), and a vertical load applied to one of the consoles. The aim is to determine the analytical dependence of the deflection of the structure on the number of mast panels in its middle part. Method. To determine the deflection, the Mohr integral is used. The forces in the rods are located simultaneously with the reactions of the supports from the general system of linear equilibrium equations of all nodes. Obtaining a solution and generalizing it to an arbitrary number of panels is obtained by induction in the Maple computer mathematics system. Results. The dependence of the deflection of the console and the displacement of the mast top on the number of panels is obtained in the form of a formula containing up to eight coefficients in the form of polynomials in the number of panels of degree no higher than the fourth. The analytical dependences of the forces in some rods as a function of the number of panels are determined.  Cubic asymptotics of the solutions is found. 10.4123/CUBS.96.2 69 Truss Mast Wind load Analytical solution Deflection Maple Induction https://unistroy.spbstu.ru/article/2021.96.2/
RAR RUS 9603-9603 57220344774 0000-0002-4043-9590 Gersevanov Research Institute of Bases and Underground Structures (NIIOSP), JSC Research Center “Stroitelstvo” Churkin Aleksei Andreevich chaa92@mail.ru
Moscow, Russian Federation
 56297902900 0000-0003-2842-4633 OZIS-Venture LLC Ulybin Alexey Vladimirovich ulybin@mail.ru
St. Petersburg, Russian Federation
 0000-0001-9404-4407 Lomonosov Moscow State University Kapustin Vladimir Viktorovich 9704361@mail.ru
Moscow, Russian Federation
 Application of Low Strain Impact Testing to Spliced Driven Piles Quality Control The object of research is an application of low strain impact testing methods to spliced driven piles quality control. The widespread opinion about the impossibility of using the method for examining composite driven piles is refuted by the results obtained in practice and requires clarification. Method. The techniques used to compensate for the limitations of the standard low strain testing methods when examining complex pile structures are enlisted. Information on the main design features of spliced driven piles is provided. Results. Models of the acoustic response behavior of different types of splices of composite piles are proposed. The features of using the low strain testing on structures of this type are highlighted. Examples of inspection of composite piles with splices of various types from the field practice of AIGEOS LLC (Moscow, Russia) and OZIS-Venture LLC (Saint-Petersburg, Russia) are given.   10.4123/CUBS.96.3 69 Pile testing Low strain Testing Spliced driven piles Guided waves Elastic waves propagation Length evaluation Defectoscopy Non-destructive testing https://unistroy.spbstu.ru/article/2021.96.3/ 9603.pdf
RAR RUS 9604-9604 6506150284 0000-0003-1139-3164 Moscow State University of Civil Engineering Sainov Mikhail Petrovich mp_sainov@mail.ru
Moscow, Russian Federation
 57204501403 0000-0003-4277-7128 Moscow State University of Civil Engineering Soroka Vladislav Borisovich
Moscow, Russian Federation
 Impact of Foundation Stiffness on Stress-Strain State of Concrete Faced Rockfill Dam Sometimes high concrete faced rockfill dams are constructed not on a rock foundation but on a soil foundation. Therefore, the urgent study is related to the impact of foundation stiffness on the stress-strain state (SSS) and strength of a concrete face. Method. The study was conducted using numerical modelling on the example of a 100 m high dam rested on a compressible foundation 100 m thick. There were considered five alternatives of foundation soil deformation modulus: from 40 MPa to 20 GPa. In addition, the impact of the seepage-control wall, which is arranged in the base, on the SSS of the hydrostatic pressure shield was investigated. High-order finite elements were used for modelling stiff thin-wall structures, which permitted obtaining a detailed pattern of stress distribution in the face. Results. Analyses showed that concrete face SSS of a dam located on a foundation of decreased stiffness is characterized not only by increased displacements but also by changing the character of their distribution. At the stiff foundation, the maximum deflections of the face are observed approximately in the middle of the dam height, and at the soft foundation, they are near the foot. Consequently, at the soft foundation, the face lower part's transversal deflection is expressed to a greater extent than in the upper part. The impact of the foundation stiffness decrease also results in the appearance of additional longitudinal forces. Conclusions. The study revealed a considerable role of the foundation stiffness in the formation of a rockfill dam concrete face SSS. Even at a strong rock foundation, the face SSS is more favourable than at an absolute stiff foundation. Therefore, in numerical modelling, it is necessary to take into account the real foundation stiffness. If a rockfill dam is constructed on the foundation more deformable than the dam's soil, then it may be expected considerable tensile, and compressive longitudinal forces may appear, which may result in loss of concrete strength. It can be recommended as a rule that the ratio of the deformation modulus of the soils of the dam and the foundation should not exceed 3. It was found that the hydrostatic pressure on the seepage-control wall at the base causes additional displacements of the base and the dam and a compressive longitudinal force in the concrete face. This leads to the growth of longitudinal forces perceived by the concrete face. 10.4123/CUBS.96.4 69 Concrete faced rockfill dam Stress-strain state Strength Soil foundation Numerical modeling Longitinual forces Lateral bending https://unistroy.spbstu.ru/article/2021.96.4/ 9604-2.pdf
RAR RUS 9605-9605 N-5291-2015 56204194000 0000-0002-5040-8106 TMH Engineering Ltd. Guchinsky Ruslan Valerievich ruslan239@mail.ru
St. Petersburg, Russian Federation
 The Onset of a Progressive Collapse During the Deconstruction of the Sports Building Preliminary modeling of the collapse process assesses labor intensity and work planning of buildings and structures dismantling. The standard procedures used in CAE in terms of structural analysis for progressive collapse may not be enough to simulate the fracture of unique buildings. This research aims to estimate the number of successive removed elements for the progressive collapse of the bearing structures of the sports building. The research object is a large stadium with a membrane roof. The bearing steel sagging membrane is attached to a reinforced concrete support ring. Methods. Simulation is performed by the finite element method with a quasilinear analysis. The plasticity of concrete is taken into account using a cylindrically anisotropic material. Results. It was found that progressive collapse is caused by fracture of the reinforcement on the inner side of the ring. Progressive collapse of the structure is possible when 13-21 load-bearing elements are removed. The force in the most loaded fastener exceeds 13 MN at fracture. A set of quasi-linear analyses can be used for the approximate estimation of the collapse during dismantling. The proposed modeling approach can be used when planning the dismantling of unique buildings. 10.4123/CUBS.96.5 69 Progressive collapse Sports building Reinforced concrete Deconstruction Fracture Finite element method Plasticity https://unistroy.spbstu.ru/article/2021.96.5/ 9605-3.pdf