Background: Improving the seismic performance of high-rise structures and reducing earthquake-induced damage are major concerns in earthquake engineering. This study investigates the seismic performance of single tuned mass dampers (STMDs) and multiple tuned mass dampers (MTMDs) in a 14-story steel moment frame. The objective is to compare the efficiency of these systems in enhancing seismic capacity, reducing structural response, and evaluating the effect of height-wise distribution based on the modal energy index.
Methods: A 14-story steel frame was modeled in different cases in OpenSees and evaluated using Incremental Dynamic Analysis (IDA). Fourteen ground motion records, including 7 far-fault and 7 pulse-like near-fault records, were used. Seven models were analyzed: one uncontrolled structure, three STMD models with mass ratios of 1%, 3%, and 5%, and three MTMD models with the same mass ratios. Structural responses were assessed in terms of roof displacement, interstory drift ratio, base shear, IDA curves, and fragility curves.
Results: Both damping systems improved seismic performance compared to the uncontrolled structure; however, MTMDs generally performed better than STMDs in most indices. The highest median collapse intensity was obtained for the MTMD model with a 5% mass ratio, reaching 4.492, a 77.37% increase over the uncontrolled structure. MTMDs with 1% and 3% mass ratios also reduced roof displacement more effectively. Fragility analysis showed that MTMDs significantly decreased the probability of exceedance.
Conclusion: MTMDs distributed along the height based on the modal energy index are more effective than a single rooftop damper in improving seismic performance and reducing failure probability of high-rise steel structures.