Book Description
Cable-stayed bridges have been recognized as the most efficient and cost effective structural form for medium-to-long-span bridges over the past several decades. With their widespread use, cases of serviceability problems associated with large amplitude vibration of stay cables have been reported. Stay cables are laterally flexible structural members with very low inherent damping and thus are highly susceptible to environmental conditions such as wind and rain/wind combination. Recognition of these problems has led to the incorporation of different types of mitigation measures on many cablestayed bridges around the world. These measures include surface modifications, cable crossties, and external dampers. Modifications to cable surfaces have been widely accepted as a means to mitigate rain/wind vibrations. Recent studies have firmly established the formation of a water rivulet along the upper side of the stay and its interaction with wind flow as the main cause of rain/wind vibrations. Appropriate modifications to exterior cable surfaces effectively disrupt the formation of a water rivulet. The objective of this study is to supplement the existing knowledge base on some of the outstanding issues of stay cable vibrations and to develop technical recommendations that may be incorporated into design guidelines. Specifically, this project focuses on the effectiveness of cable crossties, external dampers, and the combined use of crossties and dampers. Finite element simulations are carried out on the stay cable systems of constructed stay cable bridges under realistic wind forces in order to address these issues. Explicit time-history analysis enabled the performance of stay cable systems with different mitigation strategies to be assessed and compared for their relative advantages and disadvantages.
