A cointegration approach for cable anomaly warning based on structural health monitoring data: An application to cable-stayed bridges

Abstract

For long-span cable-stayed bridges, cables are one of the most important components to resist various actions. With the application of structural health monitoring technique, real-time recording of cable forces is achieved, and hence, the warning system on cable anomaly established. However, it is still difficult and there are challenges to conduct the warning system effectively, especially due to the phenomena of false alarm or omission. A practical reason is the warning index’s sensitivity to the ambient environment. Temperature variations, for instance, usually disturb the force-based cable anomaly warning and result in the false evaluation of structural condition. In view of eliminating the effects of environmental temperature, cointegration, a statistical concept from econometrics, is employed in cable anomaly warning studies. An approach that extracts warning index by linear combination of two non-stationary time series using the cointegration algorithm is developed in order to produce a more stationary cointegrated residual series (warning index series). The calculated stationary relationship between two time series is insensitive to the influence of environmental temperature and is capable of cable anomaly warning. Specifically, the framework of the cable anomaly warning system is first proposed. Subsequently, time-series test methods are introduced to check the non-stationary order and calculate the cointegration parameters of measured cable forces and environmental temperature. The computed cointegrated residual series is fed into statistical analysis as a warning index and the procedure of cable anomaly warning under the influence of environmental temperature is illustrated in detail. Finally, a case study for a cable-stayed bridge is demonstrated with results and discussions.

Structural health monitoring on Yangluo Yangtze River Bridge: Implementation and demonstration

“…The main cable and suspenders are the important load-bearing structural components in suspension bridges. The force changes in both main cable and suspenders will affect the service state of the bridge (Fan et al, 2020). The suspender tension monitoring of ICP3, ICP5, ICP8, ICP9 and ICP11 is as shown in Figure 18.…”

Probabilistic anomaly trend detection for cable-supported bridges using confidence interval estimation

“…In addition, the cointegration residual of the monitored cable force served as index to detect spikes. The details using cointegration techniques to detect anomalies are presented in our previous paper (Fan et al, 2020). The detection result is shown in Figure 17.…”

“…Zhu et al (2019) introduced the blind source separation to improve the performance of moving principal component analysis for anomaly detection by using strain data, where three cases were used to verify the effectiveness of the proposed methodology. Tome et al (2020) and Fan et al (2020) presented a strategy for early damage detection for a large cable-stayed bridge based on multivariate cointegration analysis and statistical process control, where the effects of environmental and operational variations were suppressed using cointegration analysis. Huang et al (2020) proposed a strain-based anomaly detection method for bridge main girders, where the correlation relationship between temperature and strain of the main girder was established.…”

“…Based on Figure16, anomaly event is detected with more than 95% confidence, however, the actual situation is that the anomaly detection is triggered by the spike signal, and the structure operated as usual.In addition, the cointegration residual of the monitored cable force served as index to detect spikes. The details using cointegration techniques to detect anomalies are presented in our previous paper(Fan et al, 2020). The detection result is shown in Figure17.…”

Estimation of Extreme Cable Forces of Cable‐Stayed Bridges Based on Monitoring Data and Random Vehicle Models

“…It can be seen that cable NJ21 is the longest cable (with a length of 354.53 m) of this bridge with almost the maximum force (designed as 3708 kN). Different from cable NA21, which is also a long cable but only in the side span, cable NJ21 directly supports the girder in the main span, so more attention has been paid to cable NJ21 by the bridge management department [43]. Hence, cable NJ21 in the third Nanjing Yangtze River Bridge was selected for a case study to validate the effectiveness of the proposed method.…”