## 3 Description of the Test Specimens and Test Setup  
### Test Specimens  
Five circular rebar cages with a 13.10 m (516 in) height and a 1.68 m (66 in) outside diameter, referred to as Cage #1 to Cage #5 hereafter, were used as test specimens in this study--see Figure 2. The longitudinal (\(\rho\)) and transverse (\(\rho_{s}\)) reinforcement ratios were 1.36% and 0.49%, respectively, for all specimens. Longitudinal rebars included 28 #11 (equivalent to \(\diameter 36\) in metric) rebars for all test specimens. Two different designs were used for transverse reinforcement. For Cage #2 and Cage #3, #8 (equivalent to \(\diameter 25\) in metric) welded hoops spaced at 25.4 cm (10.0 in) were used for transverse reinforcement. For the three other cage specimens (Cage #1, #4, and #5), spirals made of rebar #6 (equivalent to \(\diameter 19\) in metric) with a coil pitch of 14.0 cm (5.5 in) were used for transverse reinforcement. All five test specimens were constructed and transported with internal stiffening elements to ensure the stability of the cages before testing. Internal stiffening elements were constructed using eight diagonal #8 rebars that were welded to #8 hoops (referred to as inner rings) as shown in Figure 3. Prior to testing, the internal stiffening elements were cut in Cage #3, #4, and #5 to study the behavior of rebar cages with U-bolt connectors in the absence of internal stiffening elements.  
Except for Cage #1, which was used as the benchmark specimen with no mechanical connectors, all other cages were reinforced with U-bolts. U-bolt connectors were used on seven selected hoops (template hoops), spaced at 1.78 m (70.0 in) intervals along the cages (see Figure 2). In Cage #2, Cage #3, and Cage #4, mechanical connectors were used at every other cross-bar intersection on each template hoop. Hence, in total, 98 connectors (14 connectors/hoop \(\times\) 7 hoops = 98 connectors) were installed on each test specimen. For Cage #5, the number of mechanical connectors per template hoop was reduced to 8, resulting in 56 total connectors (8 connectors/hoop \(\times\) 7 hoops = 56 connectors). Table 1 summarizes the properties of the test specimens.  
Figure 3: Internal stiffening elements: (**a**) schematic view; (**b**) side view and dimensions (all dimensions are in cm).  
\begin{table}
**Specimen** & **Height** & **Diameter** & **Internal Stiffening** & **Number of** & **Transverse** & **Weight** \\  & **(m)** & **(m)** & **Elements** & **U-Bolt Connectors** & **Reinforcement** & **(kN)** \\ \hline \hline \end{tabular} \begin{tabular}{c c c c c c} \hline \hline \begin{tabular}{c} Cage \#1 \\ \end{tabular} & 13.10 & 1.68 & Yes & 0 & \#6 spiral @ 14 cm & 44.03 \\ \hline \hline \begin{tabular}{c} Cage \#2 \\ \end{tabular} & 13.10 & 1.68 & Yes & 98 & \#8 hoops @ 25.4 cm & 43.64 \\ \hline \hline \
\begin{tabular}{c} Cage \#3 \\ \end{tabular} & 13.10 & 1.68 & No & 98 & \#8 hoops @ 25.4 cm & 42.02 \\ \hline \hline
\begin{tabular}{c} Cage \#4 \\ \end{tabular} & 13.10 & 1.68 & No & 98 & \#6 spiral @ 14 cm & 43.84 \\ \hline \hline \end{tabular}
\end{table}
Table 1: Properties of the test specimens.  
Figure 2: Details of rebar cage test specimens: (**a**) Cage #2 and Cage #3; (**b**) Cage #1, Cage #4, and Cage #5 (all dimensions are in cm).  
Aside from mechanical connectors, tie-wires were also used to connect longitudinal and transverse rebars in all cage specimens. The pick-up bars (shown as dotted circles in Figure 2) were tied to transverse reinforcements with double-snap tie-wires at every cross-bar intersection, except those that were connected by mechanical connectors. Also, the intersections of all inner rings with longitudinal bars were tied with wrap-and-saddle double-wire-tie connections per Caltrans guidelines. Other longitudinal and transverse rebar intersections along the length of the test specimens were tied at every third intersection with single-snap tie-wire connections in all specimens. The total number of tie-wire and U-bolt connectors in each specimen is summarized in Table 2.