Effectiveness of Stationary Humans and Tuned Mass Dampers in Controlling Floor vibrations:

Floor vibrations can be annoying to stationary humans (sitting or standing) on a floor, and therefore codes and standards specify threshold values for floor acceleration levels. For very responsive floors if can be necessary to fit the floor with a passive damping source (such as a tuned mass damper) so as to ensure compliance with requirements related to human tolerance to vertical vibrations. However, the paper demonstrates that stationary humans themselves can provide a significant passive damping source due to dynamic interaction between the masses of the stationary humans and the vibrating floor. The paper presents results of controlled tests made with a vibrating test floor carrying stationary crowds of people and how these results are employed in the context of formulating a model for the passive damping mechanism generated by stationary humans.

The paper illustrates the implications of the passive damping mechanism by predicting the damping added to a set of floor systems where floor vibration is frequently of concern: on a grandstand, an office floor and a footbridge. Floor vibration levels with and without a stationary crowd atop these structures are calculated assuming a dynamic excitation generated by humans in motion. The vibration levels are compared with those expected if the else wise empty structures were fitted with a tuned mass damper so as to illustrate the effectiveness of the crowd in mitigating floor vibrations. Since a stationary crowd of people changes the dynamic characteristics of the floor which they occupy, the effectiveness of a potential tuned mass damper installation would also be influenced by the crowd's presence, and the paper quantifies the changes in damper effectiveness introduced in this way. From the results presented in the paper is would seem obvious that it can be relevant to model the passive damping mechanism brought about by stationary humans.