Experimental identification of the behaviour of and lateral forces from freely-walking pedestrians on laterally oscillating structures in a virtual reality environment

Mateusz Bocian; John H G Macdonald; Jeremy F Burn; David Redmill

doi:10.1016/j.engstruct.2015.09.043

Experimental identification of the behaviour of and lateral forces from freely-walking pedestrians on laterally oscillating structures in a virtual reality environment

Eng Struct. 2015 Dec 15:105:62-76. doi: 10.1016/j.engstruct.2015.09.043.

Authors

Mateusz Bocian¹, John H G Macdonald², Jeremy F Burn³, David Redmill⁴

Affiliations

¹ Department of Civil Engineering, University of Bristol, Queen's Building, University Walk, Bristol BS8 1TR, UK; Department of Mechanical Engineering, University of Bristol, Queen's Building, University Walk, Bristol BS8 1TR, UK; Vibration Engineering Section, College of Engineering, Mathematics and Physical Sciences, University of Exeter, Kay Building, North Park Road, Exeter EX4 4QF, UK.
² Department of Civil Engineering, University of Bristol, Queen's Building, University Walk, Bristol BS8 1TR, UK.
³ Department of Mechanical Engineering, University of Bristol, Queen's Building, University Walk, Bristol BS8 1TR, UK.
⁴ School of Experimental Psychology, University of Bristol, 12a Priory Road, Bristol BS8 1TU, UK.

Abstract

Modelling pedestrian loading on lively structures such as bridges remains a challenge. This is because pedestrians have the capacity to interact with vibrating structures which can lead to amplification of the structural response. Current design guidelines are often inaccurate and limiting as they do not sufficiently acknowledge this effect. This originates in scarcity of data on pedestrian behaviour on vibrating ground and uncertainty as to the accuracy of results from previous experimental campaigns aiming to quantify pedestrian behaviour in this case. To this end, this paper presents a novel experimental setup developed to evaluate pedestrian actions on laterally oscillating ground in the laboratory environment while avoiding the implications of artificiality and allowing for unconstrained gait. A biologically-inspired approach was adopted in its development, relying on appreciation of operational complexities of biological systems, in particular their adaptability and control requirements. In determination of pedestrian forces to the structure consideration was given to signal processing issues which have been neglected in past studies. The results from tests conducted on the setup are related to results from previous experimental investigations and outputs of the inverted pendulum pedestrian model for walking on laterally oscillating ground, which is capable of generating self-excited forces.

Keywords: Biomechanics; Bridges; CoM, centre of mass; CoP, centre of pressure; FFT, fast Fourier transform; GRF, ground reaction force; HMD, head-mounted display; Human–structure interaction; IPM, inverted pendulum model; Inverted pendulum pedestrian model; MCS, motion capture system; MIV, manipulated independent variable; NTLM, no treadmill lateral motion; NVR, no virtual reality; Self-excited forces; TLM, treadmill lateral motion; VR, virtual reality; Virtual reality environment.