## 3 Test Results and Analysis
### Mechanical Properties
#### 3.4.2 Peak Deformation  
Figure 14 indicates the variation of peak deformation of each member. For prism specimens and columns, the peak deformation refers to the axial deformation corresponding to the peak load. For bending and shear beams, the peak deformation refers to the mid-span deflection corresponding to the peak load. It can be seen from Figure 14 that the peak deformation of specimens, columns and SRRAC beams are not affected obviously by high temperatures when exposure temperatures are lower than 400 \({}^{\circ}\)C, but the peak deformation of RRAC beams decreases continuously, ranging from \(-\)80% to \(-\)13%. When exposure temperatures are larger than 400 \({}^{\circ}\)C, the peak deformation of prism specimens, columns and SRRAC shear beams increase rapidly with the high temperature. For maximum temperature of 800 \({}^{\circ}\)C, the peak deformation of prism specimens is about 2.26 times that of normal temperature, while the peak deformation of SRRAC bending beams is less affected by temperature. For maximum temperature of 600 \({}^{\circ}\)C, the peak deformation is just 1.24 times that of normal temperature. The increase of the peak deformation of prism specimens, columns and SRRAC beams is related to the increase of the internal void and the loose structure of the concrete after subjection to high temperatures, while the decrease of peak deformation of RRAC beams is due to the decrease of ductility and brittle failure with the increase of temperature.  
Figure 16: Influence of variation parameters on ductility. (**a**) Prism; (**b**) SRRAC column; (**c**) RRAC column; (**d**) SRRAC bending beam; (**e**) SRRAC shear beam; (**f**) RRAC bending beam; (**g**) RRAC shear beam; (**h**) Temperature; (**i**) Replacement percentage.  
From Figure 14i it can be found that, the effect of replacement percentage on the peak deformation of different member is different. The peak deformation of prism specimens almost increases linearly with the replacement percentage. When the replacement percentage is 100%, the peak deformation is about 1.22 times that of the replacement percentage of 0%. The peak deformation of SRRAC bending and shear beams increases first and then decreases, with the maximum increment of 39% and 32%, respectively. The peak deformation of RRAC bending beams increases with the replacement percentage, the variation range is 15%\(\sim\)37%, and the peak deformation of shear beams reduces first and then increases. The change of the replacement percentage has little effect on the peak deformation of SRRAC columns. When the replacement percentage is 70%, the peak deformation only drops by 4%, while the peak deformation of RRAC columns increases with the increase of the replacement percentage, and the increase range is 2%\(\sim\)-24%.  
Comparing RRAC members with SRRAC members, it is found that the peak deformation of RRAC columns is almost the same as that of SRRAC members with the increase of temperature, but the deformation capacity of RRAC beams decreases gradually with the increase of temperature, which is beneficial to the improvement of SRRAC members. The effect of replacement percentage on the bearing capacity of RRAC members is roughly the same as that of SRRAC members.