Dynamic modeling and vibration analysis of temporary grandstand due to crowd-jumping loads

摘要

Jumping as the most important types of crowd-induced load on a temporary grandstand, can induce excessive levels of vibration which may affect the structural safety as well as the safety and the comfortable of the spectators. In this paper, a large temporary grandstand that accommodates about 1000 persons is modeled by the ABAQUS software, jumping forces that based on a experimental results as the load incentive of the model, and the jumping duration time is 10s. The number of jumpers from 15 to 105, and the crowd jumping synchronism is 80%, 60% respectively. Among the models investigated, natural frequencies and main mode shapes were obtained. The results of the study have confirmed that spectators standing or seating load as additional mass that can lead to a substantial reduction of natural frequency. The structural dynamic response such as acceleration and displacement in the horizontal-lateral direction are sensitive to the degrees of coherency jumping, and the vibration response is no-linearly with changing the jump synchronism and number of jumpers. The amplitude spectrum has revealed that the structure dynamic frequency was closed to the natural frequency. The structure is over-conservation if the jumping load is assumed as static load value 4.5Apa. These results may be utilized in vibration serviceability assessment of temporary grandstand, and the results will be further evaluated with a temporary grandstand experiment under dynamic load induced by spectators.