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Pedestrian interaction with low-frequency structures

Researcher: Hiep Vu Dang
Project duration: 2010-2013
Supervisors: Dr Stana Zivanovic and Dr Mike Chappell
Funding body: Warwick Postgraduate Research Scholarship (WPRS) and School of Engineering

Background

Long span, slender civil engineering structures, such as footbridges, stadiums and floors, are nowadays more prone to excessive vibrations due to human-induced excitations (such as walking, running and jumping) than they were only a decade ago. This is due to somewhat inconvenient dynamic properties often encountered in modern structures made of light high-strength materials. These problematic properties are low mass and damping as well as natural frequencies being in the range of frequencies typical for human activities. To advance our understanding of in-service structural behaviour, it is necessary to develop reliable models of human-induced loading.

Most debated and still not fully understood aspect of this modelling is a phenomenon called the Human-Structure Interaction (HSI), which occurs when people who dynamically excite the structure are at the same time perceiving the vibrations induced and reacting to them. The HSI usually refers to changes in both dynamic properties of the structures and in human-induced forces caused by people’s reaction to vibration perceived. Best publicly known example of HSI is excessive lateral vibration of the Millennium Bridge on the opening day in June 2000. The bridge had to be closed shortly after its opening to be fitted with dampening devices that reduced vibrations to acceptable levels.

A lot of research in HSI in the lateral direction have been conducted since the Millennium Bridge problem occurred, but the investigation in the vertical direction stayed almost untouched. In addition, little is known how occurrence of HSI phenomenon changes the level of synchronization between people walking in groups.

Aims and Objectives

HSI occurs because the humans are intelligent dynamic systems who are highly sensitive to vibrations. Therefore, to achieve greater understanding of the phenomenon, it is necessary to understand more about human behaviours, for example how the walking-induced forces change when pedestrians are crossing perceptibly moving surfaces. To achieve this, this project will focus on studying parameters defining dynamic forces induced by pedestrians while experiencing perceptible structural motions. The main emphasis will be on the under-researched vertical component of the force induced during walking activity.

The project is currently in the initial stage concerned with combined theoretical and experimental investigations. It is intended to enhance understanding of biomechanics of human walking by tracking human motion using a state-of-the-art motion capture system VICON in the Gait lab. The data collected will be used for critical evaluation and verification of existing biomechanical models of human walking. After successful completion of this phase the project will move towards theoretical and experimental studies of pedestrian kinematics and kinetics on lively surfaces with the aim to develop an advanced computer model of human-induced forces on surfaces of different liveliness.

This research is part of the EPSRC funded project Pedestrian Interaction with Lively Low-Frequency Structures.

References

De Leva, P. (1996) Adjustment to Zatsiorsky – Seluyanov’s Segment Invertia Parameters. Journal of Biomechanics, 29 (9), 1223-1230.

Gard, S.A., Miff S.C., and Kuo, A.D (2004) Comparison of Kinematic and Kinetic Methods for Computing the Vertical Motion of the Body Center of Mass during Walking. Human Movement Science, 22, 597-610.

Geyer, H., Seyfarth, A., and Blickhan, R. (2006) Compliant leg Behaviour Explains basic Dynamics of Walking and Running. Proceedings of the Royal Society B, 273, 2861-2867.