Mitigating ground motion duration impact on steel moment-resisting frames using viscous dampers

This paper explores the significant influence of ground motion duration on the seismic performance of steel moment resisting frames. It demonstrates that during long-duration strong earthquakes, the structural response of such frames can be substantially larger than under short-duration ground motions. To address this challenge, viscous dampers, known for their stable hysteretic behavior and resistance to degradation under cyclic loading, are introduced as a retrofitting solution. To evaluate the effectiveness of viscous dampers, incremental dynamic analysis was conducted on three prototype steel moment-resisting frames of varying heights, both before and after retrofitting with viscous dampers. A total of 44 pairs of short-duration and long-duration spectrum-matched ground motions were employed as seismic inputs to isolate the effects of seismic motion duration from those arising from seismic amplitude and acceleration spectral shape. The findings underscore the potential of viscous dampers to significantly enhance the seismic performance of steel moment-resisting frames. Furthermore, these dampers effectively mitigate the impact of ground motion duration, reducing the uncertainty in structural response and facilitating more accurate evaluations of seismic performance.