## 3 Results and Analysis
### Nature of concrete
#### 3.3.3 Deformation Capability Analysis  
The story drift is the ratio of the horizontal relative displacement value between stories to the height of stories. It is mainly used to measure the deformation capacity of frame structures. In structural design specifications and the limit values of story drift are also commonly used to limit the horizontal displacement of structures.  
Under the action of the frequent earthquakes, the maximum story drift of frame structure calculated by the elastic method shall meet the requirements of the following formula:  
\[\Delta u_{e}\leq[\theta_{e}]h \tag{2}\]  
\(\Delta u_{e}\)--The maximum elastic story drift of floors due to the standard value of frequent earthquake action; \([\theta_{e}]\)--Limit value of displacement angle between elastic stories. It is used according to Table 8; \(h\)--Height of calculating floor.  
Under the action of the rare earthquake, the elastic-plastic story drift of the frame structure should meet the following requirements:  
\[\Delta u_{p}\leq[\theta_{p}]h \tag{3}\]  
\(\Delta u_{p}\)--Elastoplastic interlaminar displacement caused by standard value of rare earthquake action; \([\theta_{p}]\)--Limit value of elastic-plastic story drift, according to Table 9.  
\begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline
**Specimen** & \multicolumn{2}{c}{**Cracking Load/kN**} & \multicolumn{2}{c}{**Yield Load/kN**} & \multicolumn{2}{c}{**Ultimate Load/kN**} & \multicolumn{2}{c}{**Yield Displacement/mm**} \\ \cline{2-9}
**Number** & **Forward** & **Reverse** & **Forward** & **Reverse** & **Forward** & **Reverse** & **Forward** & **Reverse** \\ \hline KJ-1 & 20 & \(-\)20 & 148.7 & \(-\)147.4 & 213.3 & \(-\)202.9 & 14.3 & \(-\)13.5 \\ KJ-2 & 20 & \(-\)20 & 155.8 & \(-\)153.6 & 224.9 & \(-\)198.9 & 15.1 & \(-\)14.8 \\ KJ-3 & 30 & \(-\)30 & 156.6 & \(-\)148.2 & 209.3 & \(-\)219.7 & 16.4 & \(-\)15.4 \\ \hline \hline \end{tabular}
\end{table}
Table 7: Strength index of various stages.  
\begin{table}
\begin{tabular}{c c} \hline \hline
**Structural System** & \([\theta_{e}]\) \\ \hline Frame structure & 1/550 \\ Frame–shear wall structure & 1/800 \\ \hline \hline \end{tabular}
\end{table}
Table 8: Elastic story drift limit for the frameworks.  
\begin{table}
\begin{tabular}{c c} \hline \hline
**Structural System** & \([\theta_{e}]\) \\ \hline Frame structure & 1/550 \\ Frame–shear wall structure & 1/800 \\ \hline \hline \end{tabular}
\end{table}
Table 9: Elastoplastic story drift limits for the frameworks.  
The structural elastic displacement angle and elastoplastic displacement angle of the tested three frames are shown in Table 10. It can be seen from the data that the elastic displacement angle of the test frame were larger than the limit value specified in the code, which indicates that the lateral rigidity of the frame was more flexible. Compared with the three specimens, the elastoplastic story drift of specimen KJ-3 was greater than KJ-2, and KJ-2 was greater than KJ-1. This shows that under the action of the earthquake, the deformation ability of reinforced concrete frames with a low yield point was strong. The displacement angle of the test was larger than the limit value specified in the code. This was mainly because the code stipulates the displacement angle limit of the whole structure, which needs to consider the spatial effect between the components of the frame structure. The test was carried out on a single frame, ignoring the influence of other components.  
From the analysis in Table 10, it can be seen that the deformation capacity of the component was improved by using low yield point steel and high toughness concrete in the frame. In the design, the limit values of the story drift with low yield point reinforcement and high toughness concrete frame can be increased appropriately.