Journal of Sound and Vibration

Article here
Journal of Sound and Vibration - Article in press

THE PROJECT

This website is a platform from which to share some of the work currently being undertaken at the University of Nottingham as part of my Ph.D. The project is carried out within the Centre for Structural Engineering and Construction, a research group within the Faculty of Engineering. Financial support for this project is provided by the University of Nottingham.

I am investigating Pedestrian-Induced Bridge Vibration. Broadly speaking, my aim is to further clarify the human-structure interaction mechanism. Armed with this improved understanding, a further objective is to develop predictive simulation tools utilising discrete element crowd modelling techniques. The project is supervised by Dr. John S Owen and Dr. Mohammed F.M Hussein. Biomechanical input is provided by Dr. Donal McNally.

The problem of pedestrian-induced bridge vibration was highlighted by the events that took place on the London Millennium Bridge in the summer of 2000. The problem is characterised by the sudden onset of large amplitude lateral bridge oscillations when the structure is traversed by a sufficiently dense crowd. Although this is arguably the best known occurrence of the phenomenon, it's certainly not the only one. Many bridges around the world have experienced large amplitude lateral vibrations, both before and since the Millennium bridge event, e.g. The Auckland Harbour bridge in New Zealand, Toda Park bridge in Japan, Brooklyn bridge in New York, Solferino bridge in Paris as well as the Clifton Suspension bridge in Bristol.

The phenomenon of human-structure interaction leading to excessive lateral oscillations is part of a wider issue facing practicing engineers; how can the dynamic effect of pedestrian traffic be estimated during the bridge design phase? Variability and uncertainty are key features of pedestrian dynamic loading. This complicates the task facing an engineer who wishes to satisfy their clients that a bridge will be sufficiently stiff while at the same time, be constructed as economically as possible.

This project considers the problem from two perspectives; firstly the relationship between an individual pedestrian and the flexible structure on which they walk must be further clarified. Recent work within the field suggests that biomechanically led investigations offer the best chance of gaining this understanding. Therefore within this project we aim to utilise modelling and experimental techniques from the field of biomechanics to investigate pedestrian balance behaviour in the presence of base motion.

First trial runs on the new test rig
However any practical simulation tool must not only consider the relationship between an individual pedestrian and the structure, but also how this behaviour extrapolates out to a wider pedestrian crowd. To do this, behavioural relationships between pedestrians within the crowd must be considered. Thus state of the art crowd modelling techniques are employed to extract important features of crowd behaviour, principally the spatial and temporal evolution of crowd density and walking velocity.

While this project focuses on lateral bridge vibration, the methods developed are potentially applicable to any structure that may be susceptible to occupant-induced vibration, e.g. stadium structures and long-span floors.