# Experimental Study on the Seismic Performance of Recycled Concrete Hollow Block Masonry Walls
## 3 Test Results  
### Failure Phenomenon and Pattern  
The failure patterns of the five specimens are presented in Figure 8. All the specimens experienced three phases, such as cracking, peak, and failure in the experiment, but the failure process of the specimens W1, W2, and W3 were different from the specimens W4 and W5. Without structural columns, the specimens W1, W2, and W3 (bare walls) reached the ultimate strength and were destroyed immediately after the walls cracked, indicating the specimens had poor ductility and bearing capacity. On the contrary, the specimens W4 and W5 (reinforced walls) reflected better ductility and bearing capacity due to the constraints of the structural columns and ring beams. The analysis of the failure patterns of all the specimens is as follows:  
1. In the initial stage of loading, horizontal cracks occurred on both sides of the wall root of the specimen W1 due to the flexural effect. By this time, no obvious cracks occurred in the diagonal  
Figure 6: Lateral loading process.  
Figure 7: Schematic representation of the test setup.  
direction because the shear strength of the diagonal direction did not reach the cracked load. As the horizontal load increased, the horizontal cracks propagated rapidly and linked together gradually at the wall root, and the visible flexural effect was more apparent under horizontal loading. When the horizontal load reached the ultimate load, the mortar joint between the infill wall and the bottom beam was destroyed completely. Meanwhile, the specimen hardly bore the lateral load, indicating that specimen W1 failed. Therefore, the failure process of W1 was predominantly affected by the flexural effect;
2. During the initial loading stage, small horizontal cracks gradually appeared between the horizontal mortar cushion and the bottom beam of the specimen W2. As the horizontal load increased, the horizontal cracks of the wall root appeared along the ladder joints from the lower to the upper. When the lateral loads reached 80% of its ultimate loads, the cracks of the ladder joints continually widened and propagated simultaneously towards the diagonal direction. At this moment, numerous cracked blocks were spalled from the diagonal of the wall. When the lateral load increased to the ultimate load, the previously formed cracks at the diagonal direction linked together, and the bearing capacity of the specimen W2 declined rapidly, indicating that the specimen was destroyed;
3. Due to the large aspect ratio, the flexural influence on W3 was evident under the horizontal load, and the failure pattern of W3 was similar to W1;
4. In the initial loading stage, small stepped cracks appeared along the wall root and the vertical joints of the infill walls of the specimens W4 and W5. As the horizontal load increased, tiny horizontal cracks gradually appeared on both sides of the bottom of the structural columns, and other small cracks appeared at the upper oblique of the structural columns. As the horizontal load further increased, these cracks gradually widened and nearly connected, tearing apart the RCHB of the diagonal direction. When the lateral loads neared the ultimate loads, the diagonal cracks and horizontal cracks widened rapidly and linked together to form a large \"X\" shape crack under cyclic loading. At the same time, the spalling of the cracked blocks was observed in the diagonal direction of the specimens. Subsequently, the bearing capacity of the specimens reduced rapidly to 15% of its maximum values, indicating that the specimens W4 and W5 were destroyed.