Measuring and Modeling Dynamic Loads Imposed by Moving Crowds

Abstract

Excessive vibrations and deflections of modern flexible structures can be imposed by crowd movements. Dynamic forces generated by moving crowds of people while walking were measured using a specially designed, large, instrumented force platform consisting of six independent honeycomb plates. Experiments were conducted for individuals and groups of two and four people. A linear regression model was used to statistically characterize the footstep load-time history. Group loads were randomly simulated using the experimental parameters affecting individual footsteps and the coherency among the people in a group. The accuracy of the group load model is verified by frequency-domain comparison of simulated and measured data for groups of four people. Based on the work presented, loads are simulated for large crowds and design live loads are suggested for structural serviceability requirements under occupant walking activities. The design live loads vary both with footstep frequency and the size of the crowd.