Traduction Année : 2024

Crowd-structure interaction on building floors for event use

Résumé

Most of the work on floors structural dynamics generally focuses on a comfort approach and it is also useful for the designer to get practical guidelines allowing to prevent structural failure in cases of specific uses on the short-term (resonance with generalized excitation) and long-term (fatigue). Although floors structural dynamics is well-known in the field of linear behaviour, some complex loadings make it difficult to determine the loads on the structure, both in amplitude and frequency. This is the case with crowd motion, which generates a dynamic load with a specificity linked to human behaviour. Accurate modelling of crowd dynamic loading is of particular interest for buildings with light and slender floors. With the experience gained since the 1990s in grandstands or concert halls, research has begun to study the dynamic interaction between the crowd and the structure. After a general introduction to the context of the study, we recall the theoretical basis for modelling vertical action according to the type of activity. For an individual in motion, induced excitation is usually considered to be periodic, and is therefore decomposed in Fourier series. This determines the overall vertical action of the crowd, which must take into account complementary parameters such as spatial distribution and the variability of action between individuals. In addition to the ability of individuals to synchronize individually with the music source, the aim is to characterize the level of coordination between individuals and their ability to maintain the action over time. Once the action has been defined, it is necessary to describe the interaction between the crowd and the floor. The response of the structure can indeed modify the action of the crowd. Depending on the vibration levels felt, the individual can modify his or her action in amplitude, frequency, and phase. On the other hand, modal parameters of the overall structural system are also modified in the case of an active or static crowd. The various modelling methods for considering the interaction depending on the activity are reviewed. In a third part, a case study highlights the scientific and normative issues associated with event uses on floors. Practical design principles for comfort, resistance and fatigue are exposed to identify the main influential parameters and orders of magnitude. As a conclusion, the dimensioning of a viscous damper system is proposed. The fourth part is dedicated to the description of an experimental prototype inspired by the reference project comparable to a steel-concrete composite bridge. A first test campaign aims to identify the modal characteristics of the structure and the evolution of damping as a function of vibration amplitude. The structure is also studied with a system of removable viscous dampers. In a fifth section, the modal characteristics of the empty structure are identified and the results of damping tests with static and mobile individuals obtained by controlled mechanical excitation are presented. Finally, we present progressive tests with groups of active people ranging from 12 to 108. The results of the tests are described by comparing the evolution of the load and the response of the structure. In a sixth section, we specify the various important parameters that can influence the crowd behaviour. The main contribution of this experimental thesis is the evaluation of the coordination compared to the literature. This study allows to extend experimental charts up to 100 people at the same time. Secondly, we evaluate damping brought by the crowd according to the type of activity. The main purpose of this study is to propose a methodology to consider the interaction both representative of the really developed efforts and simple in its modelling.

Fichier principal
Vignette du fichier
20241021_BAUMANN.Vincent_Thesis - ENG.pdf (20.2 Mo) Télécharger le fichier
Origine Fichiers produits par l'(les) auteur(s)
Licence

Dates et versions

hal-04906126 , version 1 (22-01-2025)

Licence

Identifiants

  • HAL Id : hal-04906126 , version 1

Citer

Vincent Baumann. Crowd-structure interaction on building floors for event use. 2024. ⟨hal-04906126⟩
167 Consultations
40 Téléchargements

Partager

  • More