## 3 Experimental Results and Discussion
### Strain Responses of Frame  
Figure 21 presents the time-history curves of strains at the bottom of the column as an example under the rare earthquake intensity 8 with PGA of 1.0 g for three seismic waves. The strain envelope values subjected to the El Centro, Kobe, and Taft waves were 318, 340, and 298 \(\mu\varepsilon\), respectively, which were less than the yield strain of 1140 \(\mu\varepsilon\) deduced from the measured yield strength of Q235 steel in Table 5, indicating that the frame column was still in the elastic stage under a rare earthquake. The measured maximum strain derived from the Kobe record with stronger excitation energy seen \begin{table}
\begin{tabular}{c c c c c c c c c c} \hline \hline
**PGA** & \multirow{2}{*}{**Earthquake**} & \multicolumn{2}{c}{**Bottom**} & \multicolumn{2}{c}{**Top**} & \multirow{2}{*}{**PGA**} & \multirow{2}{*}{**Earthquake**} & \multicolumn{2}{c}{**Bottom**} & \multicolumn{2}{c}{**Top**} \\ \cline{4-9} \cline{8-10}
**(g)** & & \(\theta\) & **Average** & \(\theta\) & **Average** & & \(\theta\) & **Average** \\ \hline \multirow{3}{*}{0.1} & El Centro & 1/7182 & & 1/10505 & & El Centro & 1/1125 & & 1/1381 \\  & Kobe & 1/6167 & 1/6322 & 1/8003 & 1/8445 & 0.6 & Kobe & 1/1058 & 1/981 & 1/1115 & 1/1160 \\  & Taft & 1/5775 & & 1/7402 & & Taft & 1/818 & & 1/1036 & \\  & El Centro & 1/3560 & & 1/5103 & & El Centro & 1/972 & & 1/1208 & \\
0.2 & Kobe & 1/3185 & 1/1814 & 1/4518 & 1/4568 & 0.7 & Kobe & 1/734 & 1/877 & 1/853 & 1/1004 \\  & Taft & 1/2872 & & 1/4177 & & Taft & 1/705 & & 1/1012 & \\  & El Centro & 1/2769 & & 1/3207 & & El Centro & 1/480 & & 1/644 & \\
0.3 & Kobe & 1/2271 & 1/2310 & 1/2816 & 1/2915 & 0.8 & Kobe & 1/437 & 1/433 & 1/580 & 1/595 \\  & Taft & 1/2011 & & 1/2760 & & Taft & 1/391 & & 1/567 & \\  & El Centro & 1/2015 & & 1/2900 & & El Centro & 1/339 & & 1/518 & \\
0.4 & Kobe & 1/1812 & 1/1742 & 1/2231 & 1/2523 & 0.9 & Kobe & 1/295 & 1/303 & 1/491 & 1/494 \\  & Taft & 1/1484 & & 1/2525 & & Taft & 1/281 & & 1/475 & \\  & El Centro & 1/1437 & & 1/1611 & & El Centro & 1/250 & & 1/432 & \\
0.5 & Kobe & 1/1241 & 1/1332 & 1/1600 & 1/1550 & 1.0 & Kobe & 1/245 & 1/233 & 1/367 & 1/412 \\  & Taft & 1/1333 & & 1/1450 & & Taft & 1/209 & & 1/446 & \\ \hline \hline \end{tabular}
\end{table} 
Table 9: Maximum inter-story drift ratios under various intensity levels. Figure 20: Maximum inter-story drift ratios versus loading peak accelerations for three seismic waves. (a) El Centro wave; (b) Kobe wave; (c) Taft wave. from Figure 15 was more significant compared to that from the other two records. The strain result clearly demonstrates that the strain responses are inconsistent, even when PGA is scaled to adjust at the same level for different ground excitations, due to the individually essential factors of motion including the duration and spectrum characteristics. The measured strain responses of the model at each monitoring point under three earthquake records were obtained by the strain gauges, glued on the flange of the frame beam or column at each story. Strain gauge data were collected until the end of the test, in which the final loading PGA level was 1.6 g for the Kobe wave. The maximum tensile and compressive strains derived from the time-history strains, measured at the bottom, middle with an 800 mm height from the ground, and top with a 1600 mm height of the frame column, under the action of different seismic waves are shown in Figure 22. The strains in the column increased steadily with the increment of earthquake intensity levels. The envelope strain at the bottom of the frame column was the largest, followed by the middle, and the strain at the top was the smallest under the same PGA action, illustrating that the column base was the weakest compared to the components at the other locations of the column.