Experimental studies on lateral forces induced by pedestrians

It has been observed on a couple of cable supported footbridges that the girder vibrated laterally with a frequency of about 1.0 Hz when a large number of people crossed the bridge. The girder was excited by the lateral dynamic force which was produced by the zigzag movement of pedestrians. Once the bridge started to vibrate, some of the pedestrians synchronized with the girder vibration, which further increased the girder response. Experiments were conducted to find the pedestrians’ dynamic forces on the vibrating deck. Pedestrians walked on the specially tailored deck placed on the shake table, which was vibrated with different frequencies and amplitudes. The experiments showed that the dynamic forces induced by pedestrians increased with the amplitude of the shake table. The synchronous nature of pedestrians was also measured and clarified.