Semi-active control of walking-induced vibrations in bridges using adaptive tuned mass damper considering human-structure-interaction

Tuned mass dampers (TMDs) are used to control pedestrian induced vibrations of pedestrian bridges as traditional vibration control devices. A TMD can have a good control effect when it is tuned to the natural/vibrational frequency of the primary system. However, a traditional passive TMD is sensitive to the frequency deviation. Actual human-induced excitations can cover a wide frequency range and are stochastic virtually, which will cause a decrement in its control effect. The human-structure interaction (HSI) can also change the structural characteristic and lead to a mistuned TMD. To propose a more robust and effective TMD in solving the serviceability problem, a semi-active independent variable mass TMD (SAIVM-TMD) is introduced in this study. Wavelet transform (WT) is used to identify the structural instantaneous frequency, then, the mass of SAIVM-TMD is adjusted according to the WT - based control algorithm by actuating devices in real time. To highlight the control effect of SAIVM-TMD, a simply supported pedestrian bridge is carried out as a case study. The bridge is simplified to a Euler-Bernoulli beam according to an in-situ test and model analysis. Then, its dynamic responses under different controllers are analyzed and compared under single pedestrian periodic and stochastic walking-induced excitations. HSI is considered and a pedestrian is modulated as a moving spring-mass-damper (SMD) model. Then, a case under crowd-induced stochastic excitation is proposed. A passive TMD optimized for a pedestrian bridge under moving loads is used for comparison. Results show that SAIVM-TMD always has the best performance because it can adapt to the structural vibrational frequency changes efficiently and retune.