## 4 Experimental Results and Discussion
### Evaluation of Cylindrical Specim Behavior in the Inelastic State  
Following modern design codes [2; 3], Poisson's ratio determines concrete behavior in the transverse direction. At the same time, based on the experimental results obtained in the framework of the present study, it is very important to consider the transverse deformations over the range of the Poisson's ratios. With this aim, the dependence of the transverse deformations on longitudinal ones was analyzed. The relationship between these deformations for the first test series is shown in Figure 8. As evident from this figure, the dependence is nonlinear in the interval when \(\varepsilon_{trans}>\varepsilon_{ct\ ul}\) (see Table 3).  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline  & \multicolumn{4}{c}{**References**} \\ \cline{2-5}
**SI 466 [3]** &
\begin{tabular}{c} **[PERSON] and** \\ **[PERSON]**[22] \\ \end{tabular} & **[PERSON] [23]** & **Eurocode 2 [2]** & **[PERSON] [24]** \\ \hline
0.15... 0.25 & 0.20 & 0.20 & 0.20 & 0.15... 0.20 \\ \hline \hline \end{tabular}
\end{table}
Table 4: [PERSON]’s ratios.  
Figure 6: Experimental dependences \(\sigma_{c}\) vs. \(\varepsilon_{c}\).  
Figure 7: Experimental dependences \(\sigma_{c}\) vs. \(\varepsilon_{trans}\).  
Table 5 presents the values of the Poisson's ratios as well as the relationship between the maximum transverse, \(\varepsilon_{trans1}\), and longitudinal deformations, \(\varepsilon_{c1}\), at ULS. Following this table, the average ratio between these two parameters and the Poisson's ratio, \(\frac{\varepsilon_{trans1}/\varepsilon_{c1}}{\
u}\), is about 1.8. It should be noted that, in accordance with the structural phenomenon [13], this value should be close to 2 [6]. The difference between the obtained experimental and theoretical results is about 10%, which is explained by concrete heterogeneity and the probable technological eccentricity that was described above.  
The dependence between \(\varepsilon_{trans}/\varepsilon_{c}\) and the longitudinal deformations, \(\varepsilon_{c}\), is shown in Figure 9. This dependence is an additional tool that demonstrates the correspondence of concrete behavior with the previously developed theoretical model [6]. Following Figure 9, the value of \(\varepsilon_{trans}/\varepsilon_{c}\) increases very slowly, increasing approximately up to \(\varepsilon_{c}=0.9\) %, and then a sharp increase in this ratio is evident. This confirms that concrete behavior in this area is inelastic and corresponds to the theoretical model. According to this model, the ultimate elastic concrete behavior is limited by a longitudinal strain value of 1.0%, which correlates with the experimental value of 0.9%. At the longitudinal crack development stage caused by transverse deformations, the ratio \(\varepsilon_{trans}/\varepsilon_{c}\) tends to be 0.4%, which is approximately twice as high as it is in the elastic stage. This statement corresponds to the structural phenomenon [13].  
Figure 8: Dependences of transverse strains on longitudinal ones.  
\begin{table}
\begin{tabular}{c c c c} \hline
**Specimen** & \(\
u\) & \(\frac{\varepsilon_{trans1}}{\varepsilon_{c1}}\) & \(\frac{\varepsilon_{trans1}/\varepsilon_{c1}}{\
u}\) \\ \hline Sp1.1 & 0.15 & 0.28 & 1.86 \\ Sp1.2 & 0.22 & 0.35 & 1.57 \\ Sp1.3 & 0.16 & 0.26 & 1.63 \\ Sp1.4 & 0.15 & 0.32 & 2.13 \\ Average & 0.17 & 0.30 & 1.80 \\ \hline \end{tabular}
\end{table}
Table 5: Relationship between transverse and longitudinal strains at ULS and Poisson’s ratio values.