On real-time estimation of typhoons-induced cable tension of long-span cable-stayed bridges from health monitoring data

Cables are main bearing elements of cable-stayed bridges and can transfer loads from decks to towers. Such elements are significantly influenced by wind-rain-induced vibration. The reliable operation of the cables is extremely essential, especially when undergoing typhoons. The existing studies only identify the tension once an hour or 6 h, unable to reflect the instantaneous variation of tension. To this end, the identification of time-varying cable tension during typhoons is still a pending issue, not been resolved well. To address this issue, this study is concerned with the identification of time-varying cable tension during typhoons based on a Synchrosqueezing Wave-packet-based Instantaneous Frequency Tracking (SWIFT) algorithm. The algorithm is pretty sophisticated to first extract the time-varying instantaneous frequency via acceleration responses and then identify the variation trend of typhoon-induced tension. A field experiment on the Sutong Yangtze River Bridge (SYRB) undergoing severe typhoon Rumbia is exemplified as an engineering case to verify the method by using it to process health monitoring data. Besides, the wind characteristics, structural deformations, and displacement responses are also scrutinized to clarify the features of the variation of tensions. The results show that the proposed algorithm can identify the time-varying tension of cables during typhoons and has the potential to support a system of real-time identification and assessment of cable tension in extreme events.