## 4 Performance Analysis
### Mitigation of the Initiating Load of Slippage via Mortar Bars  
See Figure 18 for the hysteretic curves of the four specimens measured on site at the primary stage of initiating load (or the F-U1 hysteretic curves before they reach a displacement of 20 mm). Given that the wall deformation can be insignificant in comparison with the slide displacement of the upper foundation beams, \(U_{1}\)-or the foundation beam displacement measured-stands on par with \(U_{2}\)-or the displacement of loading beams.  
A visible hump can be well observed in the skeleton curves (Figure 18) of the specimens with mortar bars embedded, be it GGBW-3 or GGBW-4, as the displacement of the two varies between \(-5\) mm and \(5\) mm. However, such a hump shape tends to disappear as the displacement value rises to the range of \(5\) mm to \(10\) mm, or rather drops to \(-5\) mm to \(-10\) mm, which indicates that the roles of the mortar bars start to phase off. As shown in Figure 15, the hysteretic curves tend to fall flat as the displacement of the two specimens varies between \(-40\) mm and \(+40\) mm (right before the  
Figure 18: Force-bearing performance of mortar bars. (**a**) GGBW-1; (**b**) GGBW-2; (**c**) GGBW-3; (**d**) GGBW-4.  
failure of the mortar bars). This section can be interpreted as the hysteretic curves for the MG slide, given that the restrictive rebars come into play only when the displacement value exceeds the range of \(-40\) mm and \(+40\) mm. Additionally, at the primary stage (see Figure 17), it takes some time for the MG slide to kick in the lubrication. The slippage loading therefore climbs by a small margin. The seismic performance of the slide is stabilized afterwards.  
An analysis of Figure 18 and Table 6 indicates the following: (1) GGBW-1 and GGBW-2, which lack embedded mortar bars, display a 21.40-kN initiating load for slippage on average, whereas GGBW-3 and GGBW-4 show a 32.27% higher initiating load (27.83 kN) due to their embedded mortar bars. Therefore, the initiating load can be controlled by adding mortar bars to the specimen; (2) GGBW-3, which is reinforced by eight mortar bars, presents a 29.11-kN initiating load, and GGBW-4, which is reinforced by six mortar bars, requires a 26.54-kN initiating load. Therefore, the initiating load can also be controlled by adjusting the number of mortar bars applied and by altering the design parameters of the shear stress; (3) The hysteretic curves of GGBW-1 and GGBW-2 resemble each other, showing steady development of slide deformation. GGBW-3 and GGBW-4, which are provided with embedded mortar bars show an increase in the initiating load before the yielding of the mortar bars. However, after the shear damage of the bars occurs, the slippage loads for both specimens drop. At this point, the hysteretic loops tend to expand horizontally, indicating notable energy dissipation and seismic reduction.  
Engineering design requires two walls--perpendicular to each other--at each engineering axle perfectly fit to the masonry structure. Therefore, slide isolation measures shall be taken to the foundations in both directions. In case of earthquake, the wall--perpendicular to the one under direct seismic influence--bears the major portion of the loading imposed. Given the destructive nature of the experiment (in other words, the test stops upon the failure of the specimens) and the 0.194 ratio of slippage loading to split limit (see Table 6), the wall proposed will remain at the elastic stage under seismic influence, which lives up to the requirement of engineering design.  
The design standard for the MG isolation system has yet to be published. Therefore, the study and the research deliverables are of reference to future practice.