Inherent time-varying trends of wind records are frequently captured in recent field measurements of tropical cyclones. These observations indicate a nonstationary process that deviates from the traditional stationary assumption. In this study, a strong wind event from a landfall typhoon recorded at Sutong Bridge site (Jiangsu Province, China) in 2008 is selected for the investigation of stationary and nonstationary wind characteristics. Since the extraction of the underlying trend is usually determined by experience, a self-adaptive method is presented to automatically isolate the time-varying mean based on the signal stationarity. Once the trend is removed, the residual turbulence will naturally be stationary. Accordingly, two categories of fluctuating wind speeds are then obtained by subtracting constant or time-varying means from original wind samples. Based on the traditional stationary model and two recent nonstationary models, stationary and nonstationary turbulent wind characteristics, e.g...

Structural health monitoring system for Sutong Cable-stayed Bridge structural health monitoring system;Sutong Cable-stayed Bridge;subsystem;extension and application of SHMS; Structural Health Monitoring System (SHMS) works as an efficient platform for monitoring the health status and performance deterioration of engineering structures during long-term service periods. The objective of its installation is to provide reasonable suggestions for structural maintenance and management, and therefore ensure the structural safety based on the information extracted from the real-time measured data. In this paper, the SHMS implemented on a world-famous kilometer-level cable-stayed bridge, named as Sutong Cable-stayed Bridge (SCB), is introduced in detail. The composition and core functions of the SHMS on SCB are elaborately presented. The system consists of four main subsystems including sensory subsystem, data acquisition and transmission subsystem, data management and control subsystem and structural health evaluation subsystem. All of the four parts are decomposed to separately describe their own constitutions and connected to illustrate the systematic functions. Accordingly, the main techniques and strategies adopted in the SHMS establishment are presented and some extension researches based on structural health monitoring are discussed. The introduction of the SHMS on SCB is expected to provide references for the establishment of SHMSs on long-span bridges with similar features as well as the implementation of potential researches based on structural health monitoring.

Typhoon winds near the external eye wall of a strong typhoon are extremely nonstationary and disastrous due to its vortex and convective origin as well as its high wind speeds. However, typhoon-induced nonstationary responses of long-span bridges are currently analyzed with the assumption of time-invariant wind coherence. By taking the Stonecutters cable-stayed bridge in Hong Kong under Typhoon Hato in 2017 as an example, this paper presents the time-varying wind spectra and coherences for the bridge based on the wind data recorded by the multiple anemometers installed on the bridge. The analytical framework for nonstationary buffeting analysis of long-span bridges under typhoon winds is enhanced by considering time-varying wind coherence and applied to the Stonecutters Bridge under Typhoon Hato. The computed responses are compared with the field measurement responses. The comparative results demonstrate the feasibility and accuracy of the enhanced framework for buffeting analysis of long-span bridges with time-varying wind spectra and coherences. Comparative results with the other two cases of time-invariant coherence functions also highlight the importance and necessity of considering the time-varying wind coherence in the nonstationary buffeting analysis of long-span bridges under typhoon winds.

Because of the significant position of long-span cable-supported bridges in land transportation, the typhoon wind effects on these slender structures attract intensive attention in engineering communities. This paper presents a study about the wind effects on a kilometer-level cable-stayed bridge during Typhoon Haikui. The Sutong Cable-Stayed Bridge (SCB) with a main span of 1,088 m is taken as the research object and the structural health monitoring system (SHMS) works as a medium to provide valuable full-scale measured data. The wind characteristics, e.g., turbulence intensity, gust factor, turbulence integral scale, and power spectral density (PSD), of the severe typhoon are firstly analyzed in a statistical point of view. Specifically, the variation of turbulence PSDs in different stages is described and compared among cases at different altitudes. Then, the dynamic properties of the structure are identified with the random decrement technique, and the amplitude-dependent features are discussed. Moreover, the relationship between structural dynamic responses and the wind velocity is analyzed with a comparison to the results from the wind tunnel test. Since a significant variability is captured in structural buffeting responses, the response surface methodology (RSM) is employed to investigate influential variables in a statistical framework, which is further utilized to predict the wind-induced dynamic responses considering the variability. The observations and findings are expected to provide references for the wind-resistant analysis and design of super-long-span cable-stayed bridges.