Pedestrian Interaction with Lively Low-Frequency Structures

对高质量基础设施和提高生活质量的期望在当代社会达到了最高点。与此同时，世界正在经历快速的城市化，自然资源的压力和提供可持续建筑环境的雄心勃勃的要求。结构工程师们正在利用高强度材料，设计更高效、更轻的结构。再加上结构形式和美学的创新，所有这些因素都导致了更轻，因此更“活泼”（即更容易振动）的结构。众所周知的（热闹的）人行桥、建筑楼层和楼梯受过度振动影响而不适合预期用途的例子很多，尽管由于损害相关人员的商业声誉而倾向于将问题案例远离公众视线。现在人们普遍认为，振动适用性要求是控制这些结构的设计和决定成本的关键，其中许多结构暴露并遭受人类行走引起的动力激励。伦敦千禧桥臭名昭著的过度摇摆，十年前在人群负荷下的公开，以及随后昂贵的改造，表明迫切需要发展对行人在活跃的低频结构上行为的基本理解。虽然对行人与横向摇摆桥梁相互作用的研究已经加强，但与垂直方向上容易过度振动的更频繁的结构类相互作用的研究进展甚微。这个项目的目的是描述行人和低频结构之间的相互作用，这些结构在垂直方向上是活泼的。这种相互作用的发生是因为人类是高度复杂和敏感的动态系统，他们对周围（振动）环境做出反应和适应。目前对这种现象的理解是有限的，因此在设计指南中被忽略了。然而，这种理解对于实现适合预期用途的高质量基础设施是必要的。本项目将通过两个新的发展在这一方向上做出重大贡献：1)将开发一个独特的实验设施，包括低频结构和监测人体运动和结构振动的设备。这将克服目前缺乏这种合适的设施，并将使收集一套全面的数据成为可能，这些数据可以表征人类在活泼结构上的行为。II)在实验观察的基础上，建立人与结构相互作用的数值模型。该项目的成果将大大提高对运行条件下结构振动性能的理解，从而实现更有效和可控的设计。虽然这个为期两年的项目将侧重于研究人与结构的相互作用，但即将开发的设施将为未来的多学科研究合作提供重要的实验平台。这将使该项目的遗产在其完成日期之后得以延续。

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. This project will make significant contribution in this direction through two novel developments:I) A unique experimental facility consisting of a low-frequency structure and equipment for monitoring both human locomotion and the structural vibration will be developed. This will overcome the current lack of suitable facilities of this kind and it will enable the collection of a comprehensive set of data that characterises human behaviour on lively structures.II) Based on experimental observations, a numerical model of the interaction between humans and the structure will be developed. The outputs of this project will significantly enhance understanding of structural vibration performance in operating conditions leading to more efficient and controllable design.Although this two-year project will be focussed on studying the human-structure interaction, the facility to be developed will represent an essential experimental platform for future multidisciplinary research collaborations. This will extend the legacy of this project beyond the date of its completion.