ON THE CALCULATION OF SECTIONS REINFORCED BY REPAIR COMPOUNDS

Objectives. The aim of the study isto assess the influence of concrete deformation properties during the restoration and (or)  reinforcement of reinforced-concrete sections using repair compounds.

Methods. In the study, a method of calculation of the load-carrying capacity of concrete sections is used according to a non-linear  deformation model using diagrams of concrete deformation, taking  into account the influence of the confinement effect and prescription  factors on the deformation properties of concrete. Deformation  diagrams are constructed for short-term loading of concrete of various classes, taking into account the possible change in its  deformation properties due to its structural features (e.g. fine- grained) and the presence of modifying additives (repair concrete) in its the composition.

Results. The increase in the load-bearing capacity of a section with its total area unchanged is not directly proportional to the area of  the reinforced concrete. The increase in the loadbearing capacity of  the section is not directly proportional to the increase in the class of  concrete reinforcement. Increasing the confinement coefficient from  1.3 to 1.5 provides an increase in the loadbearing capacity of the section from 15.5% to 58%. An increase in the elastic modulus of repair concrete by 1.5 times leads to an increase in the load-bearing  capacity of the section from 19% to 50%. While keeping sectional  value and reinforcement factor constant, the use of repair concrete  makes it possible to increase the bearing capacity of the section under consideration from 1.07 to 2.25.

Conclusion. The calculation of the strength of reinforced concrete  elements reinforced with repair compounds according to the  nonlinear deformation model allows the stress-strain state (SSS) –  and, consequently, the bearing capacity after the reinforcement – to  be estimated more accurately, while the choice of the repair  compound depends on the deformation properties of the “old”  concrete.

1. Rekomendatsii po proektirovaniyu usileniya zhelezobetonnykh konstruktsii zdanii i sooruzhenii rekonstruiruemykh predpriyatii. Nadzemnye konstruktsii i sooruzheniya. M.: Stroiizdat; 1992. 191 s. [Recommendations on designing the reinforcement of reinforced concrete buildings and construction structures of the reconstructed enterprises. Overground constructions and structures. M.: Stroiizdat; 1992. 191 p. (In Russ.)]

2. Shilin A.A. Remont zhelezobetonnykh konstruktsii M.: Gornaya kniga; 2010. 519 s. [Shilin A.A. Repair of reinforced concrete structures.M.: Gornaya kniga; 2010. 519 p. (In Russ.)]

3. Shilin A.A, Pshenichnyi V.A., Kartuzov D.V. Usilenie zhelezobetonnykh konstruktsii kompozitsionnymi materialami. M.: Stroiizdat; 2004. 144 s. [Shilin A.A, Pshenichnyi V.A., Kartuzov D.V. Reinforcement of reinforced concrete constructions by composite materials. M.: Stroiizdat; 2004. 144 p. (In Russ.)]

4. Rukovodstvo po usileniyu zhelezobetonnykh konstruktsii kompozitnymi materialami. Pod rukovodstvom d.t.n., prof. V.A. Klevtsova. M.: NIIZhB; 2006. 48 s. [Guidelines for reinforcing reinforced concrete structures with composite materials. Under the guidance of Doctor of Technical Sciences, prof. V.A. Klevtsov. M.: NIIZhB; 2006. 48 p. (In Russ.)]

5. Mkrtchyan A.M., Mailyan D.R. Raschet zhelezobetonnykh kolonn iz vysokoprochnogo betona po nedeformirovannoi skheme. Nauchnoe obozrenie. 2013;11:72-76. [Mkrtchyan A.M., Mailyan D.R. Calculation of reinforced concrete columns made of high-strength concrete under the undeformed scheme. Science Review. 2013;11:72-76. (In Russ.)]

6. Muradyan V., Mailyan D., Mkrtchyan A., OsadchenkoS. Investigation of reinforced concrete columns with recessed longitudinal rods without transverse reinforcement. MATEC Web Conf. Volume 106, 2017 International Science Conference SPbWOSCE-2016 ―SMART City‖ https://doi.org/10.1051/matecconf/201710602008

7. Mailyan D.R., Abbud A., Dzhakhazhakh G. Metod rascheta szhatykh zhelezobetonnykh elementov s uchetom transformirovannykh diagramm deformirovaniya betona pri razlichnykh vozdeistviyakh: monografiya. 2008. 67 s. [Mailyan D.R., Abbud A., Dzhakhazhakh G. Method of calculation of compressed reinforced concrete elements taking into account the transformed diagrams of concrete deformation at various influences: a monograph. 2008. 67 p. (In Russ.)]

8. Rezvan I.V., Mailyan D.R. Nesushchaya sposobnost' betonnogo serdechnika trubno-betonnykh kolonn. Vestnik Maikopskogo gosudarstvennogo tekhnologicheskogo universiteta. 2011;3:18 - 25. [Rezvan I.V., Mailyan D.R. Bearing capacity of a concrete core of pipe-concrete columns. The bulletin of Maikop state technological university. 2011;3:18 - 25. (In Russ.)]

9. Aksenov V.N. K raschetu kolonn iz vysokoprochnogo betona po nedeformirovannoi skheme. Beton i zhelezobeton. 2009;1:24- 26. [Aksenov V.N. On the calculation of columns of high-strength concrete by undeformed scheme. Beton i zhelezobeton. 2009;1:24- 26. (In Russ.)]

10. Metin H. Selim P. Investigation of stress–strain models for confined high strength concrete. Sadhana.2007; 32(3):243–252.

11. Kolleganov A.V., Mailyan D.R., Nesvetaev G.V., Blyagoz A.M. Otsenka kriticheskoi konstruktivnoi prochnosti betona, podverzhennogo korrozii. Novye tekhnologii. 2012;4:122-125. [Kolleganov A.V., Mailyan D.R., Nesvetaev G.V., Blyagoz A.M. Assessment of the critical structural strength of concrete exposed to corrosion.New technologies. 2012;4:122-125. (In Russ.)]

12. Nesvetaev G.V., Kardumyan G.S. Modul' uprugosti tsementnogo kamnya s superplastifikatorami i mineral'nymi modifikatorami s uchetom ego sobstvennykh deformatsii pri tverdenii. Beton i zhelezobeton. 2013;6:10-13. [Nesvetaev G.V., Kardumyan G.S. Elasticity modulus of cement stone with superplasticisers and mineral modifiers taking into account its own strains during hardening. Beton i zhelezobeton. 2013;6:10-13. (In Russ.)]

13. Nizina T.A., Ponomarev A.N., Balykov A.S. Melkozernistye dispersno-armirovannye betony na osnove kompleksnykh modifitsiruyushchikh dobavok. Stroitel'nye materialy. 2016;9:68–72. [Nizina T.A., Ponomarev A.N., Balykov A.S. Fine-grained dispersed- reinforced concretes based on complex modifying additives. Construction Materials. 2016;9:68–72. (In Russ.)]

14. Nizina T.A., Balykov A.S. Analiz kompleksnogo vliyaniya modifitsiruyushchikh dobavok i dispersnogo armirovaniya na fiziko-mekhanicheskie kharakteristiki melkozernistykh betonov. Regional'naya arkhitektura i stroitel'stvo. 2015;4:25–32. [Nizina T.A., Balykov A.S. Analysis of the complex effect of modifying additives and disperse reinforcement on the physical and mechanical characteristics of fine- grained concrete. Regional Architecture and Construction. 2015;4:25–32. (In Russ.)]

15. Zotkin A.G. Prochnostnaya sovmestimost' tsementov s superplastifikatorami. Tekhnologii betonov. 2014;9:22–26. [Zotkin A.G. Strength compatibility of cements with superplasticizers. Concrete Technologies. 2014;9:22–26. (In Russ.)]

16. Nesvetaev G.V., Korchagin I.V., Lopatina Y.Y. On Effect of Superplasticizers and Mineral Additives on Creep Factor of Hardened Cement Paste and Concrete. Solid State Phenomena. 2017;265:109-113. https://doi:10.4028/www.scientific.net/SSP.265.109

17. Nesvetaev G.V., Davidyuk A.N. Samouplotnyayushchiesya betony (SCC): usadka. Stroitel'nye materialy. 2009;8:52-54. [Nesvetaev G.V., Davidyuk A.N. Self-compacting concrete (SCC): shrinkage. Construction Materials. 2009;8:52-54. (In Russ.)]