EXPERIMENTAL RESEARCHES OF THE BEARING CAPACITY OF REINFORCED CONCRETE BEAMS WITH DAMAGES

Visnyk LNAU: Architecture and Farm Building 2019 №20: 38-43

EXPERIMENTAL RESEARCHES OF THE BEARING CAPACITY OF REINFORCED CONCRETE BEAMS WITH DAMAGES

Blikharkyi Z., graduate student
National University "Lviv Polytechnic"
Vehera P., Candidate of Engineering Science
National University "Lviv Polytechnic"
Shnal Т. Candidate of Engineering Science
National University "Lviv Polytechnic"

https://doi.org/10.31734/architecture2019.20.038

Annotation

In the process of exploitation, all reinforced concrete structures are exposed to various influences. As a result, defects and damages occur in the elements. This article describes influence of the damaged tensile reinforcement on the bearing capacity of reinforced concrete beams. Damage is applied to reinforced concrete beams with operating load level – 0.5 from the bearing capacity of control beams. The experiment tested 10 samples. Variable parameters included the diameter of tensile reinforcement, which acquired values 16, 20, and 22 mm, and a type of damage in the form of one or five holes in the center of tensile reinforcement. All other parameters (effective depth, cross section of elements, effective length, and strength of concrete) stayed unchanged. The article presents results of the experimental tests, shows the exhaustion of the bearing capacity and the physical destruction of the samples, the graphs of deformation of tensile reinforcement, and the compressed zone of concrete. According to the test results, samples DB-2.13 and DB-2.14 are significantly less capable to carrying capacity with the working reinforcement, having the diameter of 16 mm and a deviation is 30.2%. In the samples, damaged at load levels, the load carrying capacity is approximately the same and is within the range of 3.7 ... 13.2%. A greater load bearing capacity of damaged samples at the load levels with damaged reinforcement of 20 mm in diameter (damaged area corresponds to the diameter of 16 mm) was compared to the samples with working rebar, having the diameter of 16 mm due to the hypothesis of a thermally strengthened external layer of reinforcement. Analyzing the obtained data, one can confirm that the load level, at which the damage is performed, effects the load carrying capacity of reinforced concrete samples. In that case, the residual bearing capacity is lower than in the samples with undamaged reinforcement of the similar diameter. The replacement of the bearing capacity is influenced by the initial diameter of the valve and the presence of a thermally strengthened outer layer in the stretched armature. Moreover, the type of damage effects distribution of deformations and the bearing capacity of the flexural elements. Under increased number of defects and the length, the stress concentration reduces at one point and thus, its carrying capacity decreases. According to the test results, it is established that the initial diameter of the reinforcement does not influence the residual bearing capacity of the samples.

Key words

reinforced concrete beams, damages, defects

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  1. Voskobiinyk O.P., Kitaiev O.O., Makarenko Ya.V., Buhaienko Ye.S. Experimental researches of reinforced concrete beams with defects and damages which cause slanting bend. Collection of the scientific works (Industrial machine building, construction). 2011. Vol. 1 (29). P. 87-92.
  2. Soylev T.A., Francois R. Corrosion of reinforcement in relation to presence of defects at the interface between steel and concrete. Journal of materials in civil engineering. 2005. Vol. 17, Issue 4 P. 447-455. https://doi.org/10.1061/(ASCE)0899-1561(2005)17:4(447) 
  3. Experimental investigation of the relation between damage at the concrete-steel interface and initiation of reinforcement corrosion in plain and fibre reinforced concrete / Mitchel A. et al. Corrosion Science. 2013. Vol. 77. P. 308-321. https://doi.org/10.1016/j.corsci.2013.08.019 
  4. Turchyn B. R., Blikharskyi Z. Z., Vehera P. I., Shnal T. M. Metodology of testing of reinforced cocrete beams, with damage by the load. Journal of Lviv Polytechnic National University. Series: Theory and Practice of Construction. 2017. Vol. 877. P. 212-217.
  5. Concrete and reinforced concrete construction of heavy concrete: DSTU B.V.2.6-156:2010. [valid since 2011-06-01]. Kiyv: Minrehionbud Ukrainy, 2011. 118 p. (National Standard of Ukraine).
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