Floor damping is an essential parameter in the evaluation of the dynamic performance of a floor as the amount of floor
damping has a significant impact on floor vibration levels. This paper explores the not well understood relationship
between floor damping and seated crowds of people. The paper contributes to the understanding by presenting results of
controlled experimental investigations that involved crowds of people sitting on a vibrating test floor. In tests, floor
damping and floor frequency are identified for various sizes of the crowd. This in itself throws some light on the not well
understood relationship, but it is further investigated whether modelling the human crowd as a single-degree-of-freedom
spring-mass-damper system attached to the vibrating floor can explain the recorded floor frequency and damping. Thus,
a crowd-floor interaction model describes the combined crowd-floor system, and results show that this model is capable
of explaining the overall tendency in recorded floor damping and frequency, and the calibration of the interaction model
gives some indications of the frequency and damping of the spring- mass-damper system representing the crowd. The
paper describes the tests and the methods used to evaluate the appropriateness of modelling a crowd as a spring-massdamper
system. Some implications of the observed crowd-floor interaction are discussed in light of the results.
This paper addresses a damping mechanism not often considered although typically present. The damping mechanism in question is that originating from stationary humans (standing or sitting) on floors. Floors may encounter vertical vibrations due to actions of humans in motion. The vibrations hereby generated can be a problem because stationary humans are excellent vibration sensors and may perceive vibrations as being discomforting. This paper demonstrates that in addition to acting as receivers/perceivers, stationary humans can also add significant damping to the floor which they occupy; and thus assist in reducing the discomforting vibrations. In the analyses the stationary crowd of people are modelled as an auxiliary (spring-mass-damper) system attached to the floor. Experimental results reported in this paper show that this modelling approach is reasonable even though a rigid mass assumption is often used. The latter model does not account for a human damping mechanism. Implications of its presence are evaluated for a set of floors. These evaluations also encompass the scenario that a tuned mass damper (TMD) is fitted to the floor so as to mitigate excessive floor resonant vibrations. The effectiveness of such TMD is shown to reduce substantially during the presence of stationary humans on the floor.