Vision-based estimation of vertical dynamic loading induced by jumping and bobbing crowds on civil structures

People's motion on civil structures induces dynamic loading that may lead to excessive vibrations. The complete characterization of this force distribution over a wide area due to a large number of people is still an unsolved issue. This work presents a measuring technique for the vertical load estimation in case of jumping and bobbing crowd, based on the evaluation of the vertical inertia of the human body. Laboratory experiments verify the proposed model on a single volunteer through standard inertial sensors and then extend it introducing the non-contact measuring technique. The method validation is carried out in a real environment: a stand of the G. Meazza stadium in Milan, dynamically characterized in terms of frequency response function. The load induced by groups of jumping people is estimated with the proposed method and the resulting structure accelerations are computed: the comparison between measured and estimated vibrations shows a very high correspondence in both time domain and main spectral components and, above all, the performances do not get worse as the number of volunteer increases. (C) 2012 Elsevier Ltd. All rights reserved.