Reproduction and application of human bouncing and jumping forces from visual marker data

State-of-the-art facilities for measuring bouncing and jumping ground reaction forces (GRFs) comprise typically equipment for direct force measurement, i.e. single or multiple floor-mounted force plates. Artificial laboratory conditions and constraints imposed by the direct measurement systems, such as the small measuring area of a force plate, can have a strong influence on human ability to bounce and jump, naturally yielding unrepresentative force data. However, when dealing with issues like vibration serviceability assessment of real full-scale structures, such as floors, footbridges, staircases and grandstands, there is a growing need to estimate realistic GRFs under a wide range of natural conditions. This paper presents a novel method in the civil engineering context utilising 'free-field' measurement of human bouncing and jumping forces recorded continuously in time using motion capture technology transferred and adapted from biomechanical research. Results show that this kind of data can be used successfully in studies of human-structure dynamic interaction, specifically negative cue effect of a perceptibly vibrating structure on GRFs, energy flow and power in the human-structure system, and also synchronisation between individuals when bouncing/jumping in groups on more or less perceptibly moving structures.