# Validity of Anchorage Zone Design for Post-Tensioned Concrete Members with High-Strength Strands
## 4 Experimental Results and Analysis
\begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline  & & & & \multicolumn{6}{c}{**Bearing Strain (\(10^{-6}\))**} \\ \cline{4-9}
**Group** & **No** & **Specimen** & \multicolumn{3}{c}{**Top View**} & \multicolumn{3}{c}{**Side View**} \\ \cline{4-9}  & & & **0.15 h** & **0.45 h** & **0.75 h** & **0.15 h** & **0.45 h** & **0.75 h** \\ \hline \multirow{9}{*}{A} & 1 & RH-2 & 746.48 & 113.76 & 24.88 & 592.25 & 135.07 & 21.90 \\  & 2 & CH-2 & 726.50 & 113.73 & 18.96 & 587.70 & 106.64 & 10.81 \\  & 3 & RH-3 & 1132.68 & 189.58 & 41.00 & 691.90 & 180.10 & 33.85 \\  & 4 & CH-3 & 947.88 & 163.58 & 36.78 & 618.45 & 172.51 & 30.33 \\  & 5 & RH-4 & 1350.70 & 547.38 & 71.10 & 921.50 & 300.93 & 68.27 \\  & 6 & CH-4 & 1195.00 & 537.93 & 59.72 & 870.85 & 372.03 & 54.10 \\ \hline \multirow{9}{*}{B} & - & CH-3 & 947.88 & 163.58 & 36.78 & 618.45 & 172.51 & 30.33 \\  & 7 & CS1-3 & 1051.78 & 189.60 & 57.35 & 703.76 & 143.12 & 14.93 \\ \cline{1-1}  & 8 & CS2-3 & 921.10 & 150.94 & 24.45 & 633.96 & 223.59 & 25.10 \\ \cline{1-1}  & - & CH-4 & 1195.00 & 537.93 & 59.72 & 870.85 & 372.03 & 54.10 \\ \cline{1-1}  & 9 & CS1-4 & 1415.15 & 456.60 & 26.42 & 959.43 & 428.30 & 49.24 \\ \cline{1-1}  & 10 & CS2-4 & 1230.19 & 518.87 & 53.58 & 904.16 & 299.06 & 25.47 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Bearing strain at jacking force. strands increased, compared with members using rectangular anchorages. This observation indicates that circular anchorages are more effective than rectangular anchorages at dispersing increasing bearing force and bursting force when flexural load increases. In Group B, there were no obvious tendencies for the strains of concrete and rebar in the anchorage zone according to reinforcement details. However, in Specim CS1-3, which was reinforced by Type 1 details as shown in Figure 11d, the experiment was terminated because the concrete within the local area was destroyed due to the increase of bearing force. The concrete strain of Specim CS1-3 was similar to that of Specim CH-3, which was reinforced by hairpin rebar, but the steel strain of Specim CS1-3 decreased by 38.3% compared to Specim CH-3. This is because the distance between the center of the anchorage and the center of the rebar was 195 mm in Specimen CH-3, while that in the case of CS1-3 was 680 mm. Hence, the anchorage reinforcement could not absorb the deformation caused by the stress increase of the concrete in the anchorage zone. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multirow{2}{*}{**Group**} & \multirow{2}{*}{**No**} & \multirow{2}{*}{**Specimen**} & \multirow{2}{*}{\(P_{u}\) (kN)**} & \multicolumn{2}{c}{**Strain (\(10^{-6}\))**} \\ \cline{5-6}  & & & & **Steel** & & **Concrete** \\ \cline{5-6}  & & & & **SL Gauge** & **CT1 Gauge** & **CT2 Gauge** \\ \hline \multirow{5}{*}{A} & 1 & RH-2 & 322.68 & \(-90\) & 20 & \(-46\) \\  & 2 & CH-2 & 287.21 & \(-46\) & 15.2 & \(-43\) \\  & 3 & RH-3 & 430.16 & \(-191\) & 136 & \(-13\) \\  & 4 & CH-3 & 420.84 & \(-149\) & 39 & N/A \\  & 5 & RH-4 & 461.89 & \(-61\) & 74 & \(-134\) \\  & 6 & CH-4 & 482.63 & \(-107\) & 18 & \(-35\) \\ \hline \multirow{5}{*}{B} & - & CH-3 & 420.84 & \(-149\) & 39 & \(-103\) \\  & 7 & CS1-3 & 438.95 & \(-92\) & 34 & \(-26\) \\ \cline{1-1}  & 8 & CS2-3 & 443.96 & \(-29\) & 25 & \(-45\) \\ \cline{1-1}  & - & CH-4 & 482.63 & \(-107\) & 18 & \(-35\) \\ \cline{1-1}  & 9 & CS1-4 & 504.05 & \(-276\) & 27 & \(-44\) \\ \cline{1-1}  & 10 & CS2-4 & 497.31 & N/A & 10 & \(-25\) \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Strain of reinforcement steel and concrete in the anchorage zone. Figure 11: _Cont._  
Figure 11: Cracking and failure of specimens (**a**) RH-4; (**b**) CH-4; (**c**) CH-3; (**d**) CS1-3; (**e**) CS2-3.