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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]

In a tsunami disaster, long-span bridges in coastal areas form critical transport channels for relief so it is crucial that they survive tsunami wave forces. Here we establish a dynamic response analysis framework for long-span bridges and applied it to a landslide tsunami scenario impacting a sea-crossing cable-stayed bridge near Hong Kong, China. First, a meshless numerical approach called Tsunami Squares (TS) simulated the movement of a plausible submarine landslide and its generated near-source waves. Second, we propagated the tsunami ∼300 km to the bridge site and computed wave forces on the bridge substructure. Third, we constructed a dynamic response analysis of the long-span bridge due to those forces. Results show that transverse and longitudinal forces on the bridge substructure reach maximum at different times and transverse load is larger than longitudinal load. The transverse displacement of the cable-stayed bridge dominates both longitudinal and torsional displacements but falls below the safety level even under the most extreme tsunami conditions. Landslide features have non-linear effects on tsunami waves and structural responses so a wide parameter space should be considered. The framework developed here provides effective means for assessing the dynamic state of long-span bridges during tsunami disasters. • A framework was proposed to analyze the response of the long-span bridge under potential landslide tsunamis. • Tsunami wave height and velocity may not peak at the same time. • The dominant time periods of the transverse and longitudinal tsunami wave force are different. • The influence of landslide parameters on tsunami height and corresponding bridge response shows a nonlinear growth effect. [ABSTRACT FROM AUTHOR]

• A new framework is proposed for fatigue damage prognosis of a cable-stayed bridge. • The framework considers fully-coupled vehicle-bridge dynamics. • The framework also considers deck and pavement interaction. • The framework has been applied to a real long-span cable-stayed bridge in Hong Kong. • The fatigue damage is underestimated if neglecting temperature and road roughness. • The fatigue damage is overestimated if neglecting transverse locations of vehicles. Orthotropic steel deck (OSD) in a long-span cable-stayed bridge is vulnerable to fatigue damage at the deck-to-rib (DTR) joints due to excessive vehicle-induced dynamic stresses. A framework for fatigue damage prognosis of OSD in long-span cable-stayed bridges is thus presented in this paper. The main features of the framework include hourly traffic loading simulation and prediction, multi-scale finite element bridge model, coupled vehicle-bridge system, mesh-insensitive equivalent stress responses at a DTR joint, response surface models for equivalent stress responses, OSD and pavement interaction, asphalt pavement temperature effect, fatigue test-generated S - N curve, and fatigue damage prognosis. To evaluate the feasibility of the proposed framework and to manifest the effects of pavement roughness, asphalt temperature, and vehicle transverse locations on fatigue damage accumulation, a real long span cable-stayed bridge is investigated as a case study. The results indicate that the developed framework is applicable and that the fatigue damage of a DTR joint is underestimated if the time-variant temperature of asphalt pavement and road surface condition are not considered but the fatigue damage is overestimated without consideration of variable transverse locations of vehicles. [ABSTRACT FROM AUTHOR]