Understanding wind- and rain-wind-induced stay cable vibrations.

摘要

Under certain wind conditions, stay cables of cable-stayed bridges have frequently exhibited large-amplitude vibrations. This study was conducted to understand the mechanisms of wind- and rain-wind-induced stay cable vibrations based on full-scale measurements of prototype vibrations in the field and tests of sectional models in the wind tunnel.; Observed characteristics of stay cable vibrations, as well as their correlations with wind and rain are presented. Based on these characteristics and correlations, several different types of vibrations are identified. In particular, important similarities between the frequently occurring large-amplitude rain-wind-induced vibrations and a type of large-amplitude dry cable vibration are explored, revealing a close connection between the mechanisms of large-amplitude vibrations with and with out rainfall. The similar characteristics shared by these large-amplitude vibrations are also compared with the corresponding characteristics of the classical Karman-vortex-induced vibration, providing insight into the mechanism of such large-amplitude vibrations, regardless of rainfall.; To assist interpreting the observations in the field, sectional cable models were tested in the wind tunnel, revealing the inherent vortex-induced type of instability of yawed and inclined cables over a range of high reduced velocity. The observations in the wind tunnel are also compared with the results of previous wind tunnel tests reported in the literature.; Based on the understanding from both the field and the wind tunnel, a framework is proposed for modeling of the vortex-induced type large-amplitude vibrations at high reduced velocity. The potential application of this model is also discussed.; The observed vibrations are also used to assess the performance of passive viscous dampers and cross-ties in mitigating wind- and rain-wind-induced stay cable vibrations. Recommendations for rational design of these mitigation devices are also provided. (Abstract shortened by UMI.)