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Summary: This paper presents a web‐based and design‐oriented structural health evaluation system (SHES) for long‐span bridges equipped with long‐term structural health monitoring system (SHMS). The key parameters of a long‐span bridge, used in its limit state design, are recollected. The key design parameters cover not only bridge acceleration, displacement, internal force and stress but also wind loading, temperature loading, traffic loading, earthquake excitation, and corrosion. Data analysis methods are applied to the measurement data recorded by SHMS installed in the bridge to obtain its measured/predicted key parameters. Because most design parameters are reliability‐based, data analysis methods therefore include not only statistical analysis, fatigue analysis, corrosion analysis but also extreme value analysis. The design key parameters and the measured/predicted key parameters are then used to evaluate the health status of the bridge in terms of loading, serviceability, safety, and durability. The three statuses of structural health monitoring, that is, normal monitoring, critical monitoring, and inspection initialization, are correspondingly defined as a reference for maintenance and management decision. All of the above are implemented with a series of web‐based software. The feasibility and advantage of the proposed SHES are finally demonstrated through a case study using a real long‐span butterfly arch bridge. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Typhoon winds near its external eye wall are not only strong but also nonstationary with time-varying coherences. This study proposes a conditional simulation method for multivariate nonstationary typhoon winds with time-varying coherences for long-span bridges. The Kriging method for conditional simulation and the time-varying wind spectrum and coherence are first introduced. The decomposition of the time-varying spectrum matrix is then discussed in order to obtain the time-varying correlation functions. It is found that the conventional Cholesky decomposition and the proper orthogonal decomposition (POD) are not suitable and only the square root decomposition (SRD) is appropriate for the decomposition of the spectrum matrix with time-varying coherences. Based on the field-measured nonstationary typhoon wind time histories and the time-varying spectrum and coherence models established for the Stonecutters cable-stayed bridge during Typhoon Hato, the proposed conditional simulation method is finally applied to the bridge and validated by comparing the simulated typhoon wind time histories with the measured ones as well as the unconditional simulation results. The comparative results demonstrate that the conditionally simulated wind time histories are similar to the measured ones and that the proposed conditional simulation method can be used to provide a better typhoon wind field than the unconditional simulation method. • The conditional simulation method for multivariate nonstationary typhoon winds with time-varying coherences is developed. • SRD can be used in the framework but Cholesky decomposition and POD may not be suitable. • The feasibility of the method is demonstrated by applying the method to a real cable-stayed bridge under typhoon. • The method is successful to predict typhoon wind time histories at unmeasured points of the cable-stayed bridge. [ABSTRACT FROM AUTHOR]