Excessive vibrations and deflections of modem flexible structures can be imposed by crowd movements. Forces generated by in situ activities of small groups of subjects were measured in the laboratory using a small platform. The simulated in situ forces were compared with those measured using a large floor system and simplified design loads were suggested for strength and serviceability requirements. Currently the authors are measuring and modelling input forces imposed by individuals and groups of subjects while walking, marching, and running. We measured and analyzed several sets of loads due to individuals, and groups of two and four people moving on an instrumented force platform. A simple linear regression model was used to statistically characterize the footstep load-time history. Group loads are randomly simulated by knowing the parameters affecting footsteps of an individual and coherency among the people in a group. The research also addresses the benefits and efficiency of low power semiactive control technologies to mitigate excessive structural response. The paper develops a dynamic model of an adjustable damper (i.e., a shock absorber). The performance of a simple structure is demonstrated for a simulated moving group load-time history using a suboptimal (clipped optimal) control design.

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