## 2 Materials and Methods
### Centrifuged Concrete and Reinforced, Centrifuged Concrete Specimens Preparation and Curing  
Approximately 193 reinforced concrete and 125 concrete specimens were tested for the influence of longitudinal, transverse, longitudinal and transverse reinforcement on the strength and deformability of centrifuged concrete. The samples with an external diameter of 260 mm or 500 mm, height of 400 mm or 800 mm and wall thickness from 35 mm to 80 mm were produced using single-layer centrifugation. Table 2 presents a research plan for the transverse, longitudinal and both longitudinal and transverse reinforcement effect on the strength and deformability of the centrifuged annular cross-section concrete elements. The specimens were prepared by centrifugation in support of a radial or belt type centrifuge in the factory (group B\({}_{\text{A}}\)) and laboratory (groups A, B\({}_{\text{K}}\), C\({}_{1}\), C\({}_{2}\), C\({}_{3}\)) conditions. Special metal diaphragms were used to form the specimens. All specimens curing under natural conditions for about 3 to 4 days in molds, and after disassembly they were stored under natural (temperature-humidity) conditions.  
A previous study by [PERSON] _et al._ (2018) showed that the optimal pressure at the outer diameter 500 mm of the elements is 0.1-0.2 MPa and for 260 mm is 0.01-0.02 MPa. In this case, centrifugation time is recommended from 10 to 15 min, respectively.  
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multirow{2}{*}{**Series**} & \multirow{2}{*}{**Group**} & \multirow{2}{*}{\begin{tabular}{c} **Strength of** \\ **Concrete, MPa** \\ \end{tabular} } & \multicolumn{2}{c}{**Number of Control**} & \multicolumn{2}{c}{**Series Specimens**} \\ \cline{4-6}  & & & **Annular Cross-Section** & **Number** & **Reinforcement** & **Geometrical** \\  & & & **Specimens of Concrete** & **Characteristics** & **Characteristics** \\ \hline \hline \multicolumn{6}{c}{**Investigation of the effect of transverse (spiral) reinforcement**} \\ \hline \multirow{2}{*}{**A**} & \multirow{2}{*}{**A**} & \multirow{2}{*}{30 to 50} & \multirow{2}{*}{21} & \multirow{2}{*}{34} & \(\mu_{s}=0\) & \(h=400\) mm \\  & & & & & \(\mu_{cir}=0.25\%\) to 1.25\% & \(t=36\) mm to 55 mm \\  & & & & & \(s=40,70,100\) mm & \(\phi_{\text{act}}=260\) mm \\ \hline \hline \multicolumn{6}{c}{Investigation of the effect of longitudinal reinforcement} \\ \hline \multirow{2}{*}{B} & \multirow{2}{*}{\begin{tabular}{c} B\({}_{\text{K}}\) \\ \end{tabular} } & \multirow{2}{*}{50 to 60} & \multirow{2}{*}{6} & \multirow{2}{*}{15} & \(\mu_{s}=1.0\%\) to 6.0\% & \multirow{2}{*}{\begin{tabular}{c} \(h=400,800\) mm \\ \(s=100\) mm \\ \end{tabular} } \\  & & & & & \(\mu_{cir}=45\) mm to 60 mm \\  & & & & & \(\phi_{\text{act}}=260\) mm \\ \hline \hline \multicolumn{6}{c}{Investigation of the effect of longitudinal and transverse (spiral) reinforcement} \\ \hline \multirow{2}{*}{C} & \multirow{2}{*}{\
\begin{tabular}{c} C\({}_{1}\) \\ \end{tabular} } & \multirow{2}{*}{30 to 60} & \multirow{2}{*}{86} & \multirow{2}{*}{38} & \(\mu_{s}=1.0\%\) to 6.0\% & \multirow{2}{*}{
\begin{tabular}{c} \(h=400,800\) mm \\ \(t=35\) mm to 60 mm \\ \end{tabular} } \\  & & & & & \(s=100\) mm & \\ \hline \hline \end{tabular}
\end{table}
Table 2: Research plan for the reinforcement effect of concrete strength and deformability of centrifuged annular cross-section elements. Main characteristics of test specimens.