# Mechanical Analysis of Ground Sleeve
## 6 Conclusions  
Experimental studies were performed on 16 grouted sleeve lapping connectors and three grouted splice connectors under tensile loading. The differences in the tensile capacity and failure modes between the grouted splice connector and the grouted sleeve lapping connector were studied. Analysis of the mechanical properties of the grouted sleeve lapping connector was conducted. The following conclusions can be drawn based on this research.  
(1) When the inner surface of the sleeve was smooth and all of the parameters other than the bar structural form were the same, the tensile capacity of the grouted sleeve lapping connector was 2.45 times that of the grouted splice connector, which was explained in terms of the different load transfer mechanisms of the two connectors.  
(2) Different bar configurations resulted in different failure modes for the connectors. All of the grouted sleeve lapping connectors with lapped bars failed by a bar tensile fracture or bar-grout slip, whereas the only failure mode of the grouted splice connectors with aligned bars was a grout-sleeve failure. Specific construction measures must be taken to generate a mechanical interlock force to improve the bond force between the grout and the sleeve in the grouted splice connector.  
(3) The bond stress distribution around the inserted bar in the grouted sleeve lapping connector was similar to that around a single bar anchored in concrete.  
(4) For the grouted sleeve lapping connectors, the slopes of the load-displacement curves of strain gauges installed at the middle bar inside the sleeve decreased as the load increased. As the lap length increased, the ultimate hoop compressive strain of the sleeve and the corresponding load increased.  
(5) An approximate mechanical model was put forward to describe the mechanical properties of the grouted sleeve lapping connector and was proved to be highly reliable.  
Studying the feasibility of a grouted sleeve lapping connector under a cycling load is a future research direction. It is also necessary to test the seismic behavior of precast shear walls with vertical reinforcements that are spliced by grouted sleeve lapping connectors to evaluate the operating performance of grouted sleeve lapping connectors when used in structures.  
\begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**Specimen** & **SG1/10\({}^{-6}\)** & **SG2/10\({}^{-6}\)** & **\(P_{u}\) (kN)** & **\(L_{\text{cal}}\) (mm)** & **\(\overline{L_{\text{cal}}}\) (mm)** & **\(L\) (mm)** \\ \hline
100-1 & 750 & 146 & 77.14 & 77 & & \\
100-2 & 162 & 65 & 66.67 & 178 & 114 & 100 \\
100-3 & 920 & \(-\)15 & 88.17 & 87 & & \\ \hline
150-1 & 1150 & 198 & 148.66 & 104 & & \\
150-2 & 735 & 147 & 154.92 & 156 & 163 & 150 \\
150-3 & 474 & 12 & 142.53 & 231 & & \\ \hline
200-1 & 663 & 25 & 145.61 & 180 & 180 & 200 \\ \hline \hline \end{tabular}
\end{table}
Table 5: Comparison between calculated lap length, \(L_{\text{cal}}\), and actual lap length, \(L\).  
**Author Contributions:** [PERSON] proposed the method, conceived the experiments, and wrote the paper. [PERSON] performed the experiments and analyzed the data. [PERSON] conceived and designed the experiments, analyzed the data, and wrote the paper. [PERSON], [PERSON], and [PERSON] revised the paper.  
**Funding:** The National Natural Science Foundation of China (Grant number: 51322803) supported this research.  
**Conflicts of Interest:** The authors declare no conflict of interest.