Time-dependent synchronization factor of crowd rhythmic motion and its application on intelligent structural monitoring.

The synchronization factor is an index to evaluate the level of consistency for crowd motion under rhythmic guidance, which is important for crowd load modeling as well as structural vibration monitoring. Most of the existing synchronization factors were defined based on the time history of the crowd movement over a long period of time, failing to consider the time-dependent characteristics of intra-subject variability. Moreover, these factors were generally based on the data that can only be measured under laboratory conditions, making them difficult to be applied on the monitoring of structures subjected to crowd excitation in real engineering practice. In this regard, this paper proposed a novel time-dependent synchronization factor for a crowd in rhythmic motion. By using multiple object tracking technology, the head movements of each person in the crowd were measured as the basis for calculating the newly proposed time-dependent synchronization factor, which is defined as the ratio between a representative value of the crowd movement time history and the average of the same values for each person in the crowd. A series of experiments were organized to study the characteristics and the applicability of the synchronization factor, whose relation with structural responses was clearly observed in the laboratory experiments as well as in a real structure. The results demonstrated that the newly proposed time-dependent synchronization factor is effective when applied on the intelligent operation and maintenance of the engineering structures. • A time-dependent synchronization factor describing the crowd rhythmic motion was first defined. • The algorithms for crowd head detection and crowd head tracking were trained and proposed. • The properties of the time-dependent synchronization factors for crowd motion were studied from an experimental test. • The relation between the factor and the structural responses was found through laboratory tests. • The feasibility of using the proposed factor for intelligent monitoring was tested in a real sport grandstand. [ABSTRACT FROM AUTHOR]