Study on self-adjustable tuned mass damper with variable mass

Abstract

Summary Tuned mass dampers (TMDs) represent a quite mature technology for controlling human‐induced vibrations of footbridges, when they are tuned to the primary structure's fundamental frequency. However, the TMD is very sensitive to even a small change in the tuning ratio. This paper proposes a novel TMD named self‐adjustable variable mass TMD (SAVM‐TMD), which is capable of varying its mass and retuning its frequency on the basis of the acceleration ratio between the primary system and the TMD. The accelerations are obtained from two acceleration sensors, and the frequency adjustment is achieved by using a microcontroller and actuating devices. The acceleration ratio limit value should be set in the microcontroller firstly, and when the adjustment begins, the microcontroller will retune the TMD to a reasonable frequency region, under a specific harmonic excitation. The SAVM‐TMD can be regarded as a passive control device capable of adjusting its frequency. The performance of SAVM‐TMD is studied via both experimental studies and numerical simulations under different pedestrian excitations. It is found that the SAVM‐TMD is effective in reducing the response and improving the equivalent damping ratio of the primary system when the structural frequency changes, with little power consumption. The results obtained from the experimental studies and the numerical simulations agree with each other very well. More pedestrian vibration situations are studied in the numerical simulations, and the results also show that the SAVM‐TMD has excellent performance in controlling human‐induced vibrations.

Application of an Artificial Fish Swarm Algorithm in an Optimum Tuned Mass Damper Design for a Pedestrian Bridge

“…When the external excitation is assumed to take the form F(t) = F 0 e iωt , where F 0 is the forcing amplitude and ω is its frequency. The motion equations of the dynamic system under an external excitation can be written as [1]:…”

“…However, with the development of architectural creativeness and structural technologies, they are becoming lighter and more slender, which might lead to serviceability problems under human-induced vibrations [1]. These pedestrian bridges usually have low inherent damping, and large vibrations may be caused by resonance because their natural frequency is usually located within the range of pedestrians' stride frequency.…”

Study on Adaptive-Passive and Semi-Active Eddy Current Tuned Mass Damper with Variable Damping

“…Table 5, adapted from [62], shows the first three dynamic load factors, A i and ϕ i for walking, running, and jumping, respectively, in Equation (16). The comparisons of structural response under 2.0 Hz walking, running and jumping excitations are shown in Figure 13.…”

Experimental and numerical studies of a novel asymmetric nonlinear mass damper for seismic response mitigation

“…For example, TMD was designed to have adjustable stiffness by changing its pendulum length; shape memory alloy springs were employed in TMD to adjust its stiffness property; a certain degree of nonlinearity in TMD stiffness was explored by connecting a spring to a rotating mass or inserting a very small gap between the TMD and the primary mass . In parallel with the studies of adjustable stiffness in TMDs, some methods to adjust the TMD mass and damping have also been studied . To achieve these targets, however, these adaptive TMDs further complicated the configurations, required temperature‐sensitive materials, or were only applicable to specific control situations.…”

“…34 In parallel with the studies of adjustable stiffness in TMDs, some methods to adjust the TMD mass and damping have also been studied. [35][36][37][38][39][40] To achieve these targets, however, these adaptive TMDs further complicated the configurations, required temperature-sensitive materials, or were only applicable to specific control situations.…”