Towards Enhancing Structural Sustainability of Bridge Stay cables

斜拉桥中斜拉索因风等各种环境因素引起的频繁、大振幅振动是斜拉桥长期存在的问题。在过去的几十年里，随着桥梁跨径的增加，电缆也越来越长，越来越灵活。这一点，加上它们的低固有阻尼，使得电缆振动在近年来成为一个更严重的问题。尽管人们对不同类型索的振动机制已经有了更好的了解，各种控制方法也已经提出并在现场实施，但在有无不同的减振措施的情况下，仍需要对索的动力学和空气动力学方面的特性进行评估。拟议的研究计划侧重于推进电缆动力学和空气动力学方面的知识。短期目标是：a)研究各种实际因素对干斜索驰骋激励机制的影响；b)在缆索振动的半主动控制中采用人工智能技术和自适应控制算法；C)研究智能材料作为电缆交扎的潜在应用，并评估其对电缆网络动态响应的影响；d)对结构工程和风力工程领域的HQP进行适当的培训。长期目标是：a)为开发新颖有效的结构和空气动力学措施来抑制电缆振动奠定基础；B)为完善现有斜拉索设计准则奠定坚实的基础；c)促进桥梁结构和斜拉索无损健康监测方案和损伤检测方法的发展。所提出的工作的空气动力学部分将进一步提高我们在流固耦合方面的知识，并使我们更深入地了解风致索振动的相关机制，并为开发新的空气动力学对策提供线索。将人工智能技术和自适应控制算法应用于磁流变（MR）阻尼器的半主动控制，将有助于开发一种具有成本效益的、独立于结构特性的实时电缆振动控制方案，并有效地识别阻尼器参数，从而推导出准确的逆模型。超弹性形状记忆合金（SMA）作为新型交扎材料的应用可以解决当前钢交扎的局限性，并有望大大提高电缆网络的阻尼和耐久性。拟议的研究将包括发展和促进桥梁结构健康监测、评估和管理的知识，这是一个至关重要的领域。受过这些技能训练的土木工程HQP在毕业后将有很高的需求。申请人非常有信心，拟议研究的努力将对发展更可持续和更安全的民用基础设施产生重大影响。

Frequent and large amplitude vibrations of stay cables due to various environmental factors like wind is a long-standing issue in cable-stayed bridges. In the past few decades, the growing bridge span length led to longer and more flexible cables. This, combined with their low inherent damping, renders cable vibrations a more serious problem in recent years. Though mechanisms associated with different types of cable vibration have been understood better, and various controlling methods have been proposed and implemented on site, much is still needed in appreciating the dynamic and aerodynamic aspects of cable behavior with and without the supplementation of different vibration suppression measures. The proposed research program focuses on advancing knowledge in cable dynamics and aerodynamics. The short-term objectives are: a) to study effects of various practical elements on the excitation mechanisms of dry inclined cable galloping; b) to implement AI technology and an adaptive control algorithm in the semi-active control for cable vibrations; c) to investigate the potential application of smart material as cable cross-ties and evaluate its impact on the cable network dynamic response; and d) to achieve proper training of HQP in the areas of structural engineering and wind engineering. The long-term goal aims to: a) settle the base for developing novel and effective structural and aerodynamic measures to suppress cable vibrations; b) build a sound foundation for refining the existing stay cable design guidelines; and c) contribute to the development of non-destructive health monitoring programs and damage detection methods of bridge structures and stay cables. The aerodynamic part of the proposed work will further enhance our knowledge in fluid-structure interaction, and lead to a deeper insight of mechanisms associated with wind-induced cable vibrations and shed light on developing novel aerodynamic countermeasures. The implementation of AI technology and adaptive control algorithms to semi-active control using magnetorheological (MR) dampers will allow to develop a cost-effective real time cable vibration control scheme independent of structural characteristics and efficiently identify damper parameters for deriving an accurate inverse model. The application of super-elastic shape memory alloy (SMA) as novel cross-tie material can address the limitations of the current steel cross-tie and is expected to greatly enhance damping and durability of the resulting cable networks. The proposed research will encompass the development of and contribute to the knowledge of structural health monitoring, assessment and management of bridges, which is a vitally important area. The civil engineering HQP trained with these skills will be in high demand upon graduation. The applicant is very confident that the efforts of the proposed research will have a significant impact on the development of more sustainable and safer civil infrastructures.