Experimental study of human-induced dynamic forces due to bouncing on a perceptibly moving structure

This paper describes the first direct measurements of human-induced dynamic forces due to bouncing on a perceptibly moving force platform. A unique test rig, permitting a person to bounce physically on an idealized "single-degree-of-freedom system" with variable natural frequency and mass, is described and the test methodology explained. A set of representative results for different structure and bouncing frequencies is presented for one test subject. These results clearly demonstrate the effect that the flexibility of the structure has on the levels of force and dynamic response achieved. In particular, it was established that the applied force drops considerably when the subject bounces at a frequency fairly close to the natural frequency of the structure. However, it was found that it was physically not possible to bounce at or very close to the natural frequency for the configuration of the test rig chosen. Finally, the acceleration and displacement responses indicate that both the first and second harmonies of the bouncing force are capable of producing a near resonant response.