# Retrofitting Masonry Walls against Out-Of-Plane Loading with Timber Based Panels
## 3 Experimental Study
### Large-Scale Tests
#### 3.3.2 Summary of Large-Scale Test Results  
Figure 10 shows the load-displacement curves obtained from the experiment. The average maximum load attained by the plain wall (PW1115) is 39,025 N and was chosen as a baseline to evaluate the effectiveness of the proposed timber-retrofit technique in both single-sided (1 SRW1115) and double-sided (2 SRW1115) retrofitted walls. The average maximum load and out-of-plane displacement at the specimen's mid height for 1 SRW1115 and 2 SRW1115 were estimated as (114,622 N, 25.88 mm) and (120,559 N, 12.61 mm),  
Figure 9: Large-scale test setup. respectively. In addition, the summary of the main results of the out-of-plane bending test is presented in Table 4 for the first/initial cracking and failure load, and their corresponding displacement, limiting and overall toughness. The comparison in terms of capacity at first crack (Table 4) shows that the load that caused the first crack in 1 SRW was 1.4 times the maximum load at the failure of PW. In addition, the first crack on the 2 SRW specimen occurred at a load that was 1.8 times the failure load of PW. This shows that the 2 SRW resists more load before the first crack, about 1.4 times that of 1 SRW. At the failure point, the maximum load capacity of masonry wall retrofitted with OSB panel was 2.9 times and 3.1 times that of PW for 1 SRW and 2 SRW, respectively (Table 4). Unlike the load at the first crack, the load capacity of 2 SRW was only 1.04 times that of 1 SRW. The analysis of results shows a significant increase in the out-of-plane displacement of retrofitted walls. This is due to the application of the OSB timber panel that offered the masonry wall a significant lateral resistance once the mortar interfaced cracked. As such, the retrofitted specimens were able to take more loads and absorbed more energy by displacing more without sudden failure. The increment in the out-of-plane displacement of the retrofitted walls was 6 times and 3.0 times that of PW for 1 SRW and 2 SRW, respectively. Similar to the observation in the small-scale test, the overall toughness gained due to the retrofit application when taken up to the failure of the OSB is such that an improvement of 16 times and 10 times that of the plain wall was estimated for application on single and both sides, respectively. However, the performance of the proposed technique at the limiting displacement was quite different with the double-sided showing more toughness gained than the one-sided application (2.4 \(\times\) PW and 1.6 \(\times\) PW for double and single-sided, respectively). The analysis shows that the double-sided application offers the most improvement in the toughness at the limiting displacement. Thus, the double-sided is the best option when higher energy absorption is required in a real situation. In terms of observed failure pattern (Figure 11), it emerged that the failure of the PW was sudden with the evolution of a crack opening in the mortar bed joint almost at the specimens' mid-height. The failure (cracking) abruptly occurred between the interface of the mortar joint and brick unit, which then cut across the whole specimen thickness. Whereas the application of the OSB type-3 to retrofit the walls shows that the walls were able to take more loads after the first crack, which subsequently led to the formation of other horizontal cracks in the bed joint within the middle third of the walls. The failure/collapse  
Figure 10: Load vs. displacement curve for large-scale masonry wall specimens. of the retrofitted specimens occurred when the applied OSB timber reached its ultimate strain and broke. The application ensured that sudden failure was avoided.