Pedestrian Interaction with Lively Low-Frequency Structures

对高质量基础设施和改善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，对自然资源的压力以及提供可持续建筑环境的雄心勃勃的要求。结构工程师正在通过使用高强度材料和设计更高效、更轻的结构来应对。再加上结构形式和美学方面的创新，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。已知的（活动的）人行天桥、建筑物楼层和楼梯受到过度振动影响而不适合预期用途的例子很多，尽管由于破坏了相关人员的商业声誉，有问题的案例往往远离公众视线。现在人们普遍接受振动适用性要求是这些结构的设计和成本的决定因素。其中许多暴露在由人行走引起的动态激励之下。十年前，伦敦千禧桥在人群负荷下臭名昭著的过度摇摆以及随后的昂贵改造的宣传表明，迫切需要对活跃的低频结构上的行人行为进行基本了解。虽然行人与横向摆动桥梁的相互作用的研究已经加强，与更频繁的一类结构，容易在垂直方向上过度振动的相互作用一直进展不大。本项目的目的是验证行人和低频结构之间的相互作用是活泼的垂直方向。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，他们会对周围的（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。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。该项目将通过两项新的发展在这一方向做出重大贡献：I）将开发一个独特的实验设施，包括一个低频结构和用于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，它将能够收集一套全面的数据，描述人类在活跃的结构上的行为。II）根据实验观察，将开发人类与结构之间相互作用的数值模型。该项目的成果将大大提高人们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集中于研究人-结构相互作用，但即将开发的设备将成为未来多学科研究合作的重要实验平台。这将使该项目的遗产延续到其完成之日以后。

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.