A Contribution to Documenting and Validating Dynamic Interaction Effects

On structures carrying humans (e.g. floors, grandstands in stadia etc.) there may be two different types of crowds present: Active and passive crowds of people. The active crowd, comprising people in motion, may generate dynamic loads causing the structure to vibrate. The passive (stationary) crowd, e.g. humans sitting or standing on the structure, interact dynamically with the structure in a passive sense and this crowd influences the dynamic characteristics of the structure such as its damping capacity. The paper looks into the dynamic interaction between the passive (stationary) crowd and a floor in vertical motion. The mechanism of crowd-structure interaction is not well understood and the primary aim of the paper is to present results of experimental investigations documenting effects of crowd-structure interaction and to exploring the validity of a crowd-structure interaction model. Controlled laboratory tests, employing a vibrating test floor carrying stationary crowds of people, are designed and carried out to investigate the dynamic interaction. The paper describes the tests and the modal identification procedures employed for the assessment of model validity. Besides from aspects of model validation, the experimental results also illustrate some of the essential implications of crowd-structure interaction.