Towards Enhancing Structural Sustainability of Bridge Stay cables

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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.