## 3 Seismic Performance of the Frame with CFST Dampers
### Failure Processes and Failure Modes of Three Components GJ-1, GJ-2 and GJ-3
#### 3.2.4 Simulation Analysis of GJ-2  
The failure process of energy-dissipated low-rise concrete shear wall with CFST short columns can also be divided into five stages:  
Figure 6: Failure process and failure form of GJ-1. (**a**) The first concrete plastic strain element at the beam end; (**b**) the first concrete plastic strain element of column foot; (**c**) development stage of beam and column cracks; (**d**) the beginning of the yield stage of energy dissipation device; (**e**) the crack development stage at the end of beam and column at the yield stage; (**f**) the yield stage of energy dissipation device; (**g**) stress cloud chart of reinforcement at the yield of frame column end; (**h**) cloud chart of frame tension failure; (**i**) cloud chart of frame compression failure; (**j**) cloud chart of concrete compression failure inside steel pipe; (**k**) cloud chart of concrete tension failure inside steel pipe; (**l**) cloud chart of frame stiffness degradation. 1. The crack occurrence stage: From the beginning of loading to the loading time at 1.76 s, the first plastic strain element appeared in the concrete at the left column foot. It can be seen from Figure 7a that the plastic strain value is minimal, indicating that the concrete cracking is not severe at this time and it is in a normal working state with cracks. 2. The crack development stage: With the further increase in low-reversed cyclic loading, when the loading time reached 2.75 s, the micro-cracks at the bottom of the left column began to develop horizontally to the right. At the same time, the first plastic strain element appeared at the height of the cut at the left end of the energy-dissipated low-rise concrete shear wall with CFST short columns (Figure 7b). When the loading time reached 4.56 s, cracks began to appear at the bottom of the right column and at the height of the cut (Figure 7c). With the further increase in displacement, the cracks at the bottom of the shear wall developed horizontally and basically connected in the left and right directions (Figure 7d). 3. The beginning of the yield stage: The cracks mentioned above further developed, and new cracks continued appearing. The short CFST column at the cut position in the wall began to yield, and the lower half of the shear wall began to have cracks that developed diagonally from left to right (Figure 7e), and the main load-bearing bar of the shear wall began to yield. 4. The yield stage: With the increase in displacement, the short CFST column in the wall yielded further, and the main load-bearing bars of the columns on both sides also yielded (Figure 7f). The cracks at the upper left corner of the lower half of the shear wall started to develop further diagonally to the right and downward, and finally connected to the compression zone at the lower right corner, which is referred to as the right oblique cracks (Figure 7g,h). With the negative unloading and reloading, the cracks in the upper left to the lower right direction of the wall in the lower half began to narrow and shorten. On the contrary, cracks appeared from the upper right corner to the lower left corner and finally penetrated the compression zone at the lower left corner, referred to as the left oblique cracks (Figure 7i,j), showing obvious \"X\" shaped cross cracks. When negative unloading and reloading again, the second right oblique crack appeared in the wall's lower half, and the direction was parallel to the first right oblique crack (Figure 7k). The concrete began to bulge and finally reached the maximum horizontal bearing capacity of the model. At this time, the horizontal loading displacement was 17.014 mm. 5. The failure stage: After yielding of the main load-bearing bars of the CFST short columns, and the frame columns on both sides and the lower half of the shear wall, the cracks further increased with the increase in the reciprocal load. The cracks in the lower part of the shear wall were dense, and the concrete was basically crushed in the later stage.