Abstract: As one of the three fundamental characteristics of ground motion, ground motion duration has a significant impact on the aseismic performance of structures, yet it has not been fully addressed in current aseismic design codes. A five-storey reinforced concrete frame structure compliant with Chinese aseismic design codes was designed. A numerical model was developed using MSC. Marc finite element software, and pairs of ground motions with a matched response spectra but different durations (long and short) were generated through spectral matching. Using Incremental Dynamic Analysis (IDA), the study systematically evaluated the effects of duration on structural dynamic responses, post-earthquake recoverability, and seismic loss. The results indicate that under seismic events of rare intensity or greater, ground motion duration has a significant amplifying effect on structural displacement responses. The maximum inter-storey drift ratio under rare earthquakes increases by approximately 7.0%. This amplification effect becomes more pronounced with increasing seismic intensity. In contrast, the influence of duration on floor accelerations remains relatively limited. In terms of post-earthquake recoverability, long-duration motions reduced structural post-earthquake recoverability by 6.9%. From an economic perspective, long-duration ground motions increased the maximum total loss by approximately 13.0%, while the impact on average annual loss was relatively small, with an increase of about 5.1%.