Towards Enhancing Structural Sustainability of Bridge Stay cables

斜拉索在风等各种环境因素作用下的振动频率大，是斜拉桥中长期存在的问题。在过去的几十年里，随着桥梁跨度的不断增长，拉索变得更长、更灵活。这一点，再加上其固有的低阻尼，使得近年来电缆振动成为一个更加严重的问题。尽管人们对不同类型拉索振动的机理有了更好的了解，并提出了各种控制方法并在现场实施，但在有或没有不同减振措施的情况下，仍需要更多地了解拉索行为的动力学和空气动力学方面。拟议的研究计划侧重于提高缆索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拉索舞动激励机制的影响；(B)将人工智能技术和自适应控制算法应用于拉索振动的半主动控制；(C)研究智能材料作为拉索横杆的潜在应用，并评估其对索网动力响应的影响；以及(D)在结构工程和风工程领域实现HQP的适当培训。长期目标是：a)为开发新颖有效的结构和空气动力学措施以抑制拉索振动奠定基础；b)为完善现有的斜拉索设计指南奠定坚实的基础；以及c)为桥梁结构和斜拉索的无损健康监测计划和损伤检测方法的发展做出贡献。拟议工作中的空气动力学部分将进一步增强我们在流固相互作用方面的知识，并使我们更深入地了解与风致拉索振动相关的机理，并为开发新的空气动力学对策提供启示。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中，可以开发出一种经济有效的独立于结构特性的实时拉索振动控制方案，并有效地识别阻尼器参数以得到准确的逆模型。超弹性形状记忆合金(SMA)作为新型交叉系索材料的应用可以解决目前钢制交叉系绳的局限性，并有望大大提高索网的减振和耐久性。拟议的研究将包括桥梁结构健康监测、评估和管理知识的发展和促进，这是一个极其重要的领域。经过这些技能培训的土木工程总部在毕业后的需求量将会很大。申请人非常相信，拟议研究的努力将对更可持续和更安全的民用基础设施的发展产生重大影响。

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.