Cable effective length model error-based bridge performance warning method under thermal action

Abstract

The cables of long-span cable-stayed bridges are subjected to substantial tension during long-term service and are more susceptible to corrosion and fatigue failure than concrete structures. Most existing structural health monitoring (SHM) systems do not have monitoring equipment to directly measure cable length, and long-term monitoring of the change in cables is less involved. The displacement response of a bridge is induced by the combination of dynamic effects (wind and highways) and quasi-static effects (temperature). In this paper, the dynamic responses were eliminated by averaging the displacement data for 10 min, and the relationship between temperature and displacement was studied. Based on the monitoring data, the distribution of the thermal field for the bridge was studied and the time variability of the tower displacement was investigated. The correlation was analyzed to study the relationship between the temperature and the tower displacements, the north tower–south tower distance and the tower–girder distances. A strong linear relationship between the temperature and quasi-static responses of the displacements was observed. The thermal expansion coefficient of the effective length of cables was proposed as a quantitative index for long-term cable monitoring. The error in the cable effective length is proposed as the warning index for performance warning research. The results show that the proposed performance warning method can monitor cables and perform warnings when the cable is damaged.

Thermal behaviors of bridges — A literature review

“…Wang et al (2022) investigated the temperature effect on the tower deformation using the SHM data of a cable-stayed bridge. A strong linear relationship between the air temperature and the tower deformation was observed.…”

“…They also reported that the actual girder temperature profile agreed well with that recommended by the British standard, while the transverse temperature difference of the deck was non-negligible. Wang et al (2022) investigated the temperature effect on the tower deformation using the SHM data of a cablestayed bridge. A strong linear relationship between the air temperature and the tower deformation was observed.…”

Early warning for abnormal strains of continuous bridges using a proposed temperature–strain mapping model

“…Previous research [5,18] showed that both the dynamic and static responses of bridges are closely related to temperature. For cable stayed bridges, the tower deformation, girder strains and cable's natural frequency are almost linearly related with temperature changes [19][20][21]. The linear relationship has also been used to consider temperature effects or verify the effectiveness of the temperature extraction method.…”