Computational
simulation of the coupled system (crowd-structure interaction)
The dynamic interaction model between crowd and structure is based on the decomposition of the complex system into interacting subsystems (segregated approach or partitioned analysis) and on their time-domain analysis. The classic Finite Element Method is used for the structural model discretisation, while the computational simulation of the crowd system is obtained on the basis of the Finite Difference Method. The structure, the crowd and the force model have been implemented in an ad hoc developed computational code, named C.S.I., provided with an efficient graphical user interface for current usage in design practice.
Figure 1 – C.S.I. code Graphical User Interface
The approach has been validated with respect to in situ measurements on an actual footbridge during real crowd events (Toda Park bridge, Japan). This approach allows, on one hand, the main features of the phenomenon to be simulated (traffic jams, stop-and-go phenomena, crowd-to-structure synchronisation, synchronisation among pedestrians) and, on the other, synthetic results, that are useful to designers and engineers, to be obtained (peak lateral acceleration of the deck for a given incoming crowd density or minimum crowd density triggering a given lateral acceleration).
