The results of the experimental studies of reinforced concrete structures of hydraulic structures with interconnect construction joints, reinforced by external reinforcement of carbon fiber

Vestnik MGSU 9/2018 Volume 13
  • Rubin Oleg D. - Scientific Research Institute of Energy Structures (Open Joint-stock Company) Doctor of technical sciences, General Director, Scientific Research Institute of Energy Structures (Open Joint-stock Company), 7a Construction travel, Moscow, 125362, Russian Federation.
  • Lisichkin Sergey E. - Engineering Center of Structures, Constructions and Technologies in Power Engineering (Limited Liability Company) Doctor of technical sciences, Deputy General Director, Engineering Center of Structures, Constructions and Technologies in Power Engineering (Limited Liability Company), 35 Freedom st., Moscow, 125364, Russian Federation.
  • Frolov Kirill E. - Public Joint-Stock Company Federal Hydro-Generating Company - RusHydro (PJSC «RusHydro») engineer, Deputy Director General of Scientific and Project Activities, Public Joint-Stock Company Federal Hydro-Generating Company - RusHydro (PJSC «RusHydro»), 51 Architect Vlasov st., Moscow, 117393, Russian Federation.

Pages 1067-1079

For the purposes of experimental validation of application of external reinforcement of carbon fiber to reinforce reinforced concrete structures of hydraulic structures the experimental models of typical structures of hydraulic structures with inter-block construction joints were tested. At the same time, beam-type models of concrete of class B15 with a reinforcement percentage of 0.39 % and concrete of class B25 with a reinforcement percentage of 0.83 % were tested for the effect of bending moment. The models of fragments of reinforced concrete structures of hydraulic structures of concrete class B15 with a reinforcement percentage of 0.445 % and concrete B25 with a reinforcement percentage of 0.7 % were tested for сentral extension. Reinforced concrete beam-type models were reinforced with external reinforcement of carbon tapes of the type FibArm 530/300. Models of hydraulic structures fragments were reinforced by external reinforcement from carbon tapes of the type FibArm Tape 530/300 and from carbon composite lamellae of the type FibArm Lamel 12/50. The reinforced concrete beam-type models were reinforced with carbon strips (longitudinal bands on the lower stretched face and transverse belts in the span and supporting zones). The models of fragments of reinforced concrete structures of hydraulic structures were reinforced with carbon strips and carbon composite slats directed along the action of longitudinal tensile force. The results of experimental studies showed a significant increase in the strength of reinforced concrete structures of hydraulic structures due to their reinforcement by external reinforcement of carbon fiber, and also revealed a special character of the crack formation due to the presence of inter-block construction joints. Subject of the research: the subject of the study: reinforced concrete structures of hydraulic structures (with interblock construction joints), reinforced with external reinforcement of carbon fiber. Materials and methods: reinforced concrete models were made from ordinary heavy-weight concrete of classes B15 and B25 and reinforcement of A500C class. The outer reinforcement was made of carbon tapes of the type FibArm Tape 530/300 and FibArm Lamel12 / 50. Experimental studies were carried out on the basis of physical modeling of characteristic reinforced concrete structures of hydraulic structures with interblock building joints. In this model, the beam type of concrete class B15 with a percentage of reinforcement of 0.39 % and of concrete class B25 with a percentage of reinforcement 0.83 % were tested for the action of bending moment. Models of fragments of reinforced concrete structures of hydraulic structures from concrete class B15 with a reinforcement percentage of 0.445 % and of concrete B25 with a reinforcement percentage of 0.7 % were tested for the effect of central stretching. Experimental models were equipped with control and measuring equipment for determining the values of deflections, deformations of concrete and reinforcement elements of models, crack opening width and interblock joints. Results: in the course of experimental studies, a significant increase in the strength of reinforced concrete structures of the hydraulic structures (in 1.47-2.34 times) was obtained under the action of the bending moment and the central extension due to their reinforcement by external reinforcement from the carbon fiber. Conclusions: based on the obtained experimental data on the significant increase in the strength of reinforced concrete structures of hydraulic structures (by 1.47-2.34 times) due to reinforcement by carbon composite tapes and carbon composite lamella, the substantiation of the use of external reinforcement from carbon bands and lamellas under the action of a bending moment and central extension. Also, a special type of cracking was observed, due to the presence of interblock joints, the study of which allows controlling the implementation of technical solutions for reinforcing, repairing, reconstructing reinforced concrete structures of hydraulic structures.

DOI: 10.22227/1997-0935.2018.9.1067-1079

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Basic functions and bilateral estimatesin the stability problems of elastic non-uniformly compressed rods expressed in terms of bending moments with additional conditions

Vestnik MGSU 2/2014
  • Kupavtsev Vladimir Vladimirovich - Moscow State University of Civil Engineering (MGSU) Candidate of Physical and Mathematical Sciences, Associated Professor, Department of Theoretical Mechanics and Aerodynamics, Moscow State University of Civil Engineering (MGSU), 26 Yaroslavskoe shosse, Мoscow, 129337, Russian Federation; This e-mail address is being protected from spambots. You need JavaScript enabled to view it .

Pages 39-46

The method of two-sided evaluations is extended to the problems of stability of an elastic non-uniformly compressed rod, the variation formulations of which may be presented in terms of internal bending moments with uniform integral conditions. The problems are considered, in which one rod end is fixed and the other rod end is either restraint or pivoted, or embedded into a support which may be shifted in a transversal direction.For the substantiation of the lower evaluations determination, a sequence of functionals is constructed, the minimum values of which are the lower evaluations for the minimum critical value of the loading parameter of the rod, and the calculation process is reduced to the determination of the maximum eigenvalues of modular matrices. The matrix elements are expressed in terms of integrals of basic functions depending on the type of fixation of the rod ends. The basic functions, with the accuracy up to a linear polynomial, are the same as the bending moments arising with the bifurcation of the equilibrium of a rod with a constant cross-section compressed by longitudinal forces at the rod ends. The calculation of the upper evaluation is reduced to the determination of the maximum eigenvalue of the matrix, which almost coincides with one of the elements of the modular matrices. It is noted that the obtained upper bound evaluation is not worse thanthe evaluation obtained by the Ritz method with the use of the same basic functions.

DOI: 10.22227/1997-0935.2014.2.39-46

References
  1. Kupavtsev V.V. Variatsionnye formulirovki zadach ustoychivosti uprugikh sterzhney cherez izgibayushchie momenty [Variational Formulations of the Problems of Elastic Rods Stability Using Bending Moments]. Vestnik MGSU [Proceedings of Moscow State University of Civil Engineering]. 2010, vol. 3, no. 4, pp. 285—289.
  2. Alfutov N.A. Osnovy rascheta na ustoychivost' uprugikh sistem [Fundamentals of the Stability Analysis of the Elastic Systems]. Moscow, Mashinostroenie Publ., 1991, 336 p.
  3. Kupavtsev V.V. Dvustoronnie otsenki v zadachakh ustoychivosti uprugikh sterzhney, vyrazhennykh cherez izgibayushchie momenty [Bilateral Estimates in Elastic Rod Stability Problems Formulated through Bending Moments]. Vestnik MGSU [Proceedings of Moscow State University of Civil Engineering]. 2013, no. 2, pp. 47—54.
  4. Rektoris K. Variatsionnye metody v matematicheskoy fizike i tekhnike [Variational Methods in Mathematical Physics and Engineering]. Moscow, Mir Publ., 1985, 589 p.
  5. Doraiswamy Srikrishna, Narayanan Krishna R., Srinivasa Arun R. Finding Minimum Energy Configurations for Constrained Beam Buckling Problems Using the Viterbi Algorithm. International Journal of Solids and Structures. 2012, vol. 49, no. 2, pp. 289—297. DOI: 10.1016/j.ijsolstr.2011.10.003.
  6. Panteleev S.A. Dvustoronnie otsenki v zadachakh ob ustoychivosti szhatykh uprugikh blokov [Bilateral Assessments in the Stability Problem of Compressed Elastic Blocks]. Izvestiya RAN. MTT [News of the Russian Academy of Sciences. Mechanics of Solids]. 2010, no. 1, pp. 51—63.
  7. Santos H.A., Gao D.Y. Canonical Dual Finite Element Method for Solving Post-buckling Problems of a Large Deformation Elastic Beam. International Journal of Non-Linear Mechanics. 2012, vol. 47, no. 2, pp. 240—247. DOI: 10.1016/j.ijnonlinmec.2011.05.012.
  8. Selamet Serdar, Garlock Maria E. Predicting the Maximum Compressive Beam Axial Force During Fire Considering Local Buckling. Journal of Constructional Steel Research. 2012, vol. 71, pp. 189—201. DOI: 10.1016/j.jcsr.2011.09.014.
  9. Tamrazyan A.G. Dinamicheskaya ustoychivost' szhatogo zhelezobetonnogo elementa kak vyazkouprugogo sterzhnya [Dynamic Stability of the Compressed Reinforced Concrete Element as Viscoelastic Bar]. Vestnik MGSU [Proceedings of Moscow State University of Civil Engineering]. 2011, vol. 2, no. 1, pp. 193—196.
  10. Manchenko M.M. Ustoychivost' i kinematicheskie uravneniya dvizheniya dinamicheski szhatogo sterzhnya [Dynamically Loaded Bar Stability and Kinematic Equations of Motion]. Vestnik MGSU [Proceedings of Moscow State University of Civil Engineering]. 2013, no. 6, pp. 71—76.

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BILATERAL ESTIMATES IN ELASTIC ROD STABILITY PROBLEMS FORMULATED THROUGH BENDING MOMENTS

Vestnik MGSU 2/2013
  • Kupavtsev Vladimir Vladimirovich - Moscow State University of Civil Engineering (MGSU) Candidate of Physical and Mathematical Sciences, Associated Professor, Department of Theoretical Mechanics and Aerodynamics, Moscow State University of Civil Engineering (MGSU), 26 Yaroslavskoe shosse, Мoscow, 129337, Russian Federation; This e-mail address is being protected from spambots. You need JavaScript enabled to view it .

Pages 47-54

In the article, the author proposes an original method of identification of upper and lower bounds of critical values of loading parameters in respect of three stability problems for a non-uniformly compressed rectilinear one-span elastic rod with a varying longitudinal bending stiffness value.Initial variational formulations of stability problems under consideration are presented through internal bending moments that emerge at the moment of the rod stability loss and that satisfy uniform boundary conditions rather than additional integral conditions. The author has obtained forms of the bending moment and respective loading parameter values in case of the rod equilibrium bifurcation in the basic problem of stability of an elastic rectilinear rod with a constant cross section, compressed by longitudinal forces at the rod ends.The calculation of the lower bound is reduced to determination of the greatest eigenvalues for the matrices presented in the form of modular matrices of the second order with the elements expressed through the integrals of available forms of bending moments. The calculation of the upper bound is reduced to determination of the greatest eigenvalue for the matrix that almost coincides with one of modular matrices.

DOI: 10.22227/1997-0935.2013.2.47-54

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  3. Kupavtsev V.V. O variatsionnykh formulirovkakh zadach ustoychivosti sterzhney s uprugo zashchemlennymi i opertymi kontsami [Variational Formulations of Stability Problems for Rods That Have Elastically Fixed and Supported Ends]. Vestnik MGSU [Proceedings of Ìoscow State University of Civil Engineering]. 2011, vol. 3, no. 4, pp. 283—287.
  4. Kupavtsev V.V. K dvustoronnim otsenkam kriticheskikh nagruzok neodnorodno szhatykh sterzhney [On Bilateral Evaluations of Critical Loading Values in Respect of Non-uniformly Compressed Elastic Rods]. Izvestiya vuzov. Stroitel’stvo i arkhitektura. [News of Institutions of Higher Education. Construction and Architecture]. 1984, no. 8, pp. 24—29.
  5. Panteleev S.A. Dvustoronnie otsenki v zadachakh ob ustoychivosti szhatykh uprugikh blokov [Bilateral Assessments in the Stability Problem of Compressed Elastic Blocks]. Izvestiya RAN. MTT. [News of the Russian Academy of Sciences. Mechanics of Solids]. 2010, no. 1, pp. 51—63.
  6. Izhendeev A.V. Otsenka vnutrennikh usiliy tonkostennogo sterzhnya otkrytogo profilya [Assessment of Internal Forces of a Thin-walled Rod with an Open Profile]. Izvestiya vuzov. Stroitel’stvo. [News of Institutions of Higher Education. Construction]. 2004, no. 3, pp. 100—103.
  7. Chanyshev A.I., Igonina E.A. O potere ustoychivosti beskonechno dlinnoy polosy za predelom uprugosti pri szhatii [On the Loss of Stability of an Indefinitely Long Strip beyond the Elasticity in Compression]. Fizicheskaya mezomekhanika [Physical Mesomechanics]. 2010, vol. 13, no. 51, pp. 89—95.
  8. Paymushin V.N., Gyunal I.Sh., Lukankin S.A. Issledovanie kachestva nelineynykh uravneniy teorii uprugosti na zadachakh ustoychivosti ploskikh krivolineynykh sterzhney sloistoy struktury (postanovka zadachi) [Research into the Quality of Non-linear Equations of the Theory of Elasticity Exemplified by the Problems of Stability of Flat Curvilinear Rods That Have a Layered Structure (Problem Definition)]. Izvestiya vuzov. Aviatsionnaya tekhnika. [News of Institutions of Higher Education. Aeronautical Engineering]. 2010, no. 2, pp. 34—37.
  9. Dudchenko A.V., Kupavtsev V.V. Dvustoronnie otsenki ustoychivosti uprugogo konsol’nogo sterzhnya, szhatogo polusledyashchey siloy [Bilateral Estimates of Stability of an Elastic Cantilever Rod, Compressed by the Half-tracking Force]. Vestnik MGSU [Proceedings of Ìoscow State University of Civil Engineering]. 2011, no. 6, pp. 302—306.
  10. Dudchenko A.V., Kupavtsev V.V. Dvustoronnie otsenki ustoychivosti uprugogo konsol'nogo sterzhnya, szhatogo cherez shatun [Bilateral Estimates of Stability of an Elastic Cantilever Rod, Compressed over the Connecting Rod]. Vestnik MGSU [Proceedings of Ìoscow State University of Civil Engineering]. 2012, no. 7, pp. 75—81.

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