Semi-Active Tuned Mass Dampers for Vibration Control of Random Crowd Load

Abstract:

To improve the serviceability of footbridge， a semi-active tuned mass damper（STMD） with variable mass and damping is proposed， which can not only adjust its own mass and frequency in real time to adapt to the dynamic characteristics of the footbridge through the water pump and electromagnetic valve， but also adjust its own damping coefficient in real time to improve the effect of energy dissipation through changing the air gap of eddy current damping. First， the variable mass and damping algorithm and model test of STMD are introduced. Then， a case study is conducted based on the probabilistic random model of crowd excitation. Afterwards， the 100 times acceleration response of the structure without control， with an optimized passive TMD， variable mass STMD， variable damping STMD and variable mass and damping STMD under random synergistic crowd is studied. Through the maximum， mean and standard deviation of the three comfort evaluation indexes of the 100 groups of acceleration， root mean square（RMS） value， and maximum 1-s RMS value， the control performance and robustness of different TMDs are analyzed. The results show that structural dynamic responses vary greatly due to the randomness of crowd and body parameters. In general， STMD with variable mass and damping has the best control performance， whose standard deviation is also the smallest， indicating the best robustness.

Key words:semi-active tuned mass damper（STMD）;stochastic crowd excitation;human-structure interaction (HSI）;variable mass;variable damping