# Concrete Beams Reinforced with High Strength Rebar in Combination with External Steel Tape
## 2 Materials and Methods  
### Experimental Investigation  
For the study, 8 reinforced concrete beams with 2600 mm length, 2400 mm estimated span, and 120 \(\times\) 240 mm cross-section were designed, manufactured, and experimentally tested. Corresponding calculations were performed for this samples for one-span beam with two supports and loaded by two concentrated forces in thirds of the span. At the first stage, the goal was to assemble beams with different percentages of reinforcement and with different ratios of high-strength reinforcement to tape reinforcement. It was accepted that their calculated strength according to DSTU B.V.2.6-156:2010 [43] and Eurocode 2 [44] should be the same; thus, the destructive load for them was assumed to be the same. This assumption simplified the comparison of experimental results and increased their accuracy. Combined reinforcement, including the S275 steel tapes of 8 mm thickness and A1000 class high-strength rebar of 10 mm diameter, was used in the stretched zone of the test samples. The reinforcement in the compressed zone of the experimental beams is designed with a periodic profile of 8 mm A400S steel bars. Steel bars of the 5 mm A240 class were installed with 70 mm spacing at the supports and 100 mm spacing in the pure bending zone, which served as transverse reinforcement and as anchors for tape S275 reinforcement. The concrete that was used had the grade C35/45. The components of the concrete were the following: the concrete (C) of M600 class, rubble (R) of 5-20 mm size fraction, quartz sand (S), unadulterated water (W), and plasticizer NK-1 (VM). The ratio of components was C:R:S:P = 1:1:25:2.67:0.0055; W/C = 0.4. The beams were designed in such a way that their destruction occurred in the zone of pure bending due to the action of the bending moment. The designed beams were divided into four series in order to increase the reliability of the test results. Each series consisted of two identical beams that were manufactured and tested under the same conditions. In beams of the B-I and B-II series, combined reinforcement of the stretched zone with A1000 reinforcement and S275 tape was used. In beams of the B-III and B-IV series, no combined reinforcement was used; they served as the test samples for further comparison and analysis of the results of their work with the results of beams B-I and B-II. Beams of B-III series were reinforced with 3 high-strength 10 mm steel bars of A1000S class. Beams of the B-IV series were reinforced with only tape reinforcement of the S275 class with a thickness of 8 mm. Characteristics of the test samples are given in the Tables A1 and A2 (see Appendix A)  
In beams of series B-I, tape reinforcement was used with total area A\({}_{\text{s}}\) = 6.56 cm\({}^{2}\), which was 89.64% of the total area of the stretched reinforcement and 1-10 mm A1000 rebar with area A\({}_{\text{s}}\) = 0.758 cm\({}^{2}\), which amounted to 10.36%. For series B-II, tape reinforcement was used with total area A\({}_{\text{s}}\) = 3.68 cm\({}^{2}\), which was 70% of the total area of the stretched reinforcement and 2-10 mm A1000 rebar with area A\({}_{\text{s}}\) = 1.57 cm\({}^{2}\), which amounted 30%. In beams of series B-III in stretched zone, high-strength steel bars of 3-10 mm A1000 with area A\({}_{\text{s}}\) = 2.355 cm\({}^{2}\) were used. In beams of series B-IV in stretched zone, tape reinforcement of S245 steel with area A\({}_{\text{s}}\) = 9.12 cm\({}^{2}\) was used. The construction of experimental beams' frames is given on Figure 1.  
Figure 1: Construction of experimental beams’ frames. For experimental reinforced concrete beams, it was important to calculate the strength of the anchors, which should ensure reliable contact of the concrete with the external smooth tape reinforcement. In ordinary reinforced concrete structures, the joint work of reinforcement and concrete is almost always ensured by the reliable adhesion.