# Mechanical Analysis of Ground Sleeve
## 4 Comparison between Grouted Splice Connectors and Grouted Sleeve Lapping Connectors  
### Tensile Capacity  
Table 2 shows the tensile capacity of the grouted splice connectors and grouted sleeve lapping connectors with the same bar anchorage length of 100 mm. When the inner surface of the sleeve was smooth and parameters other than the bar structural form were identical, the average tensile capacity of the grouted sleeve lapping connectors was 2.45 times that of the grouted splice connectors. This result showed that the lap of the bars enabled the grouted sleeve lapping connectors to provide much greater bearing capacity than the grouted splice connectors with aligned bars.  
This result can be explained by the difference in the load transfer between the two types of connectors. In the grouted splice connector, the tensile force was transferred from one bar to the other though two paths. In Path I, part of the tensile force was transferred through the grout to the sleeve wall by the bond, which is similar for the other bar [13; 18]. In Path II, the remainder of the force was transferred through the surrounding grout to the other bar directly. The load transfer paths are shown in Figure 11.  
In addition to the same load transfer paths as the grouted splice connector, a third path (Path III) is available for the grouted sleeve lapping connector, in which part of the force is transferred though the grout between the bars directly. Path III is depicted in Figure 12, which shows the section passing through the centerline of the two bars. In this load transfer path, the two bars extruded each other, which creates a tendency for the two bars to move away from each other [37; 38; 39]. The expansion degree of the grout increased, and the radial confinement provided by the sleeve became stronger. The sleeve made a higher contribution for providing transverse confinement in the grouted sleeve lapping connector, which, in turn, increased the ultimate bearing capacity of the connector [40].  
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Type** & **Specimen** & \begin{tabular}{c} **Bar Anchorage** \\ **Length (mm)** \\ \end{tabular} & \begin{tabular}{c} **Tensile** \\ **Capacity (kN)** \\ \end{tabular} & \begin{tabular}{c} **Average Tensile** \\ **Capacity (kN)** \\ \end{tabular} & **Failure Mode** \\ \hline \multirow{3}{*}{\begin{tabular}{c} Grouted splice \\ connector \\ \end{tabular} } & S-200-1 & \multirow{3}{*}{100} & 33.78 & \multirow{3}{*}{31.53} & \multirow{3}{*}{\begin{tabular}{c} Grout-sleeve slip \\ Grout-sleeve slip \\ Grout-sleeve slip \\ Grout-sleeve slip \\ \end{tabular} } \\  & S-200-3 & & 34.53 & & \\ \hline \multirow{3}{*}{\
\begin{tabular}{c} Grouted sleeve \\ lapping \\ connector \\ \end{tabular} } & 100-1 & \multirow{3}{*}{100} & 77.14 & \multirow{3}{*}{77.33} & \multirow{3}{*}{
\begin{tabular}{c} Bar-grout slip \\ Bar-grout slip \\ Bar-grout slip \\ \end{tabular} } \\  & 100-2 & & 88.17 & & \\ \hline \hline \end{tabular}
\end{table}
Table 2: Comparison between the grouted splice connector and the grouted sleeve lapping connector.  
Figure 11: Load transfer path of the grouted splice connector.