Observations of bridge stay cable vibrations in dry and wet conditions: A case study

https://doi.org/10.1016/j.jsv.2021.116106Get rights and content
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Highlights

  • Large vibration amplitudes of the stay cables of the Stavanger City Bridge (Norway) were occasionally reported.

  • A monitoring system including accelerometers, an anemometers and a field camera was deployed.

  • Rainfall was found to promote the onset of large amplitude heave oscillations.

  • The range of mean wind speed values, reduced velocities and wind-cable angles associated with rain-wind-induced vibrations was characterised.

  • The displacement trajectories during significant oscillation amplitudes in wet conditions exhibited a near-elliptical shape.

  • The formation of the rainwater rivulets on the stay cable surface was also documented.

Abstract

The characteristics of wind- and rain-wind-induced vibrations of bridge stay cables are studied by using ambient vibrations records acquired on a cable-stayed bridge. Mean wind speed and wind-cable angle, as well as the occurrence of rainfalls, were investigated to diagnose a possible excitation mechanism promoting the onset of large heave amplitude oscillations, which were occasionally reported. Light rainfall, mean wind speed values between 8 ms1 and 12 ms1 and wind-cable angle ranging 45 to 65 were found to be critical conditions for the onset of large amplitude vibrations for the cases at hand. A single-mode response (eigenmode 3) associated with reduced velocities around 35 was generally activated during large cable oscillations (peak-to-peak amplitudes of twice the cable diameter) in wet conditions. The simultaneous video camera recordings also contributed to an improved understanding of the upper rainwater rivulet formation and the mechanism of stay cable vibrations in wet state.

Keywords

Bridge stay cables
Full-scale
Cable dynamics
Rain-wind-induced vibrations
Water rivulets

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