Principal investigator:	Dr Stana Zivanovic
Research staff:	Mr Hiep Vu Dang
Project duration:	2011-2013
Funding body:	EPSRC (£124.2k)

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Summary

The expectation for high-quality infrastructure and improved quality of life is at its highest point in contemporary society. At the same time the world is experiencing fast urbanisation, pressure on natural resources and ambitious requirements to provide a sustainable built environment. Structural engineers are responding by utilising high-strength materials and designing more efficient and lighter structures. Coupled with innovations in structural forms and aesthetics, all these factors lead towards lighter and therefore 'livelier' (i.e. more vibration prone) structures. Examples of known (lively) footbridges, building floors and staircases affected by excessive vibrations and unfit for the intended purpose are numerous, despite the tendency to keep the problematic cases far from the public eye due to damaging commercial reputations to those involved.

It is generally accepted now that vibration serviceability requirements are governing the design and determining the cost of these structures, many of which are exposed and suffer from the dynamic excitation induced by human walking. Publicity of the infamous excessive sway of the Millennium Bridge, London, under crowd loading ten years ago, and subsequent expensive retrofitting, demonstrated an urgent need to develop fundamental understanding of pedestrian behaviour on lively low-frequency structures. While research into pedestrian interaction with laterally swaying bridges has since intensified, the interaction with a more frequent class of structures that are prone to excessive vibrations in the vertical direction has been progressed little.

The aim of this project is to characterise the interaction between pedestrians and low-frequency structures that are lively in the vertical direction. The interaction occurs because humans are highly sophisticated and sensitive dynamic systems who react to and adapt to the surrounding (vibrating) environment. Current understanding of this phenomenon is limited and consequently it is ignored in design guidelines. However, it is this understanding that is necessary for achieving high-quality infrastructure fit for intended use. The aims of this project are to:

• Build a unique experimental facility for studying the interaction,
• Develop a numerical model of the interaction, and
• Perform experiments to quanitfy the interaction and verify the numerical model.

The outputs of this project will enhance understanding of structural vibration performance in operating conditions leading to more efficient and controllable design. The facility to be developed will represent an essential experimental platform for future multidisciplinary research collaborations extending the legacy of this project beyond the date of its completion.

More information on this project can be found here.