Dozens of human-induced load models for individual walking and jumping have been proposed in the past decades by researchers and are recommended in various design guidelines. These models differ from each other in terms of function orders, coefficients, and phase angles. When designing structures subjected to human-induced loads, in many cases, a load model is subjectively selected by the design engineer. The effects of different models on prediction of structural responses and efficiency of vibration control devices such as a tuned mass damper, however, are not clear. This article investigates the influence of human-induced load models on performance of tuned mass damper in reducing floor vibrations. Extensive numerical simulations were conducted on a single-degree-of-freedom system with one tuned mass damper, whose dynamic responses to six walking and four jumping load models were calculated and compared. The results show a maximum three times difference in the acceleration responses among all load models. Acceleration response spectra of the single-degree-of-freedom system with and without a tuned mass damper were also computed and the response reduction coefficients were determined accordingly. Comparison shows that the reduction coefficient curves have nearly the same tendency for different load models and a tuned mass damper with 5% mass ratio is able to achieve 50%–75% response reduction when the structure’s natural frequency is in multiples of the walking or jumping frequency. All the results indicate that a proper load model is crucial for structural response calculation and consequently the design of tuned mass damper device.
This article presents a hybrid approach for determining optimal parameters of multiple tuned mass dampers to reduce the floor vibration due to human walking. The proposed approach consists of two parts. The first one is a partial mode decomposition algorithm to efficiently calculate dynamic responses of the coupled floor–multiple tuned mass damper system subjected to moving walking loads. The second one is an adaptive genetic simulated annealing method for the optimization of multiple tuned mass damper parameters. To establish optimization, certain variables must be considered. These include the mass, natural frequency, and damping ratio of each tuned mass damper in a multiple tuned mass damper system. The objective is to minimize floor responses and remove unreasonable requirements, such as uniform mass distribution and symmetric distribution of the tuned mass damper frequency. The proposed hybrid approach has successfully been applied to optimize the multiple tuned mass damper system to reduce the vibration of a long-span floor with closely spaced modes. By the hybrid approach, an extensive parametric study has been carried out. The results show that different walking load models and uncertainties in the dynamic properties of the floor and each tuned mass damper itself can affect the overall performance of the multiple tuned mass damper system. The proposed hybrid optimization approach is very effective and the resulting multiple tuned mass damper system is robust in reducing floor vibrations under various conditions.
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