PSI - Issue 36

O. Kononchuк et al. / Procedia Structural Integrity 36 (2022) 177–181 O. Kononchu к , V. Iasnii, N. Lutsyk / Structural Integrity Procedia 00 (2021) 000 – 000

179

3

a)

b)

Fig. 2. Stress-strain diagrams of concrete: a) typical monochromatic (Kachlakev et al. (2001)); b) experimental under compression (Kononchuk et al. (2017), Kotynia (2005)).

Table 1. Characteristics of concrete for FE simulation. Name of parameters

Value of parameters

Modulus of elasticity E 0 , МPа

23.95  10 3

Calculation value of concrete compression strength f cd , МPа Calculation value of concrete when stretching f сt , МPа

24.31

2.8 0.2 0.2

Poisson's ratio 

Open shear transfer coefficient ( β t ) Closed shear transfer coefficient ( β c )

1

According to experimental studies, the loading was chosen as 1 kN  m for FEM. 3. Results and discussion The modelling results of deflections and strains of the reinforced concrete beams components are shown in Figs. 3, 4 and 5. Experimental curves were plotted based on averaged data of experiments. The relationships between bending moment and strain of the strengthened RC beams defined experimentally and by FEM for primary reinforcing bars and external composite material are demonstrated in Figure 4. They show the behaviour of bending reinforced concrete beams before and after their strengthening by CFRP materials under the action of one loading cycle. The results, obtained by FEM and experimental results are very similar. The advantage of numerical simulation is the possibility of studying the strength characteristics of the structure until failure. This process cannot be defined experimentally because of the rapid development of deflections, deformations, cracks and the complexity of their fixation.