Non-linear dynamic analysis of Collapsed grandstand

Abstract

Abstract On the 17th of October 2021 a grandstand of the Goffert stadium partially collapsed while a crowd was jumping on it. It was concluded that the main reason of the collapse was that the load of a jumping crowd exceeded the design load of 4 kN/m2, as specified in the NEN 6702. The load also exceeds the current design load of 5 kN/m2 NEN-EN 1991-1-1. A geometrically and physically non-linear finite element (FEM) model was used to obtain the backbone curve of the response of the grandstand. The push-down analysis was force-controlled to allow the grandstand to rotate and deform freely, so that the failure mechanism could develop freely. The jumping load was modelled with a Fourier series based on the contact ratio, the coordination, and the weight of the crowd. These three parameters were estimated with video footage of the collapse. The mass of the people was roughly 3.5 kN/m2. An equivalent SDOF system was set up based on analytical formulae and the backbone curve. With this model the non-linear dynamic behaviour of the grandstand was assessed. Failure was found with the estimated jumping load after roughly the same number of jumps as was seen on video.