Experimental study of bridge stay cable vibration



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Texas Tech University


Rain and wind induced vibration in the stay-cables of stay-cable bridges is a problem that is generating greater attention as more of these bridges are constructed around the world. At issue is the possibility of fatigue of the stay-cable attachments at the bridge deck and tower as well as the material that makes up the stay-cable itself. The vibrations are most prevalent during moderate to heavy rain and light wind conditions below 30 mph, but also occur at high wind speeds with no rain. The proposed cause of the vibration problem is the change in cross-sectional shape of the stay-cable that occurs when rain forms one or more beads, or rivulets, along the cable surface. This modified cross section affects the aerodynamics of the stay-cable and, as a result, large vibrations occur at wind speeds well above the known vortex shedding wind speeds for cylindrical bodies. Often, these large magnitude vibrations were not accounted for by the bridge designers and engineers and modification of existing cables becomes necessary. This work presents the existing schools of thought on the mechanism that causes the extreme vibrations of stay-cables. In addition, a section model suspension and force measuring system is developed to study the behavior of stay-cables in the wind tunnel. Data are presented from a stay-cable section model study using the above mentioned force measuring system. Further, suggestions are made for future study of the stay-cable vibration problem based on the results of this work and the work of other researchers.



Cable-stayed, Bridges