A comparative study on the transient wind-induced response of long-span bridges subject to downbursts and typhoons

•The Hilbert spectrum-based method and the two-dimensional (2D) indicial response function was introduced in the time domain buffeting analysis of a long-span bridge under nonsynoptic events.•The downburst wind presents significantly nonstationarity characterized by time-varying mean and spectrum, while slightly nonstationary nature was observed in the typhoon events.•The downburst-induced transient effects on the indicial response function, aeroelastic loads and buffeting response were highlighted, while negligible transient effects were observed under typhoon events. Inherent nonstationarity of the wind speed records is frequently captured during downburst and typhoon events, however, the significance of nonstationary effects on the bridge aerodynamics has not been widely investigated yet. In this study, the nonstationary wind-induced effects on aerodynamics under downburst and typhoon events were discussed. More specifically, the wind field input was generated using the instantaneous information embedded in the Hilbert spectrum, which was extracted from full-scale measurements of downburst and typhoon wind. The two-dimensional (2D) indicial response function was employed in the time domain buffeting analysis of a long-span bridge, and the transient effects on the bridge aerodynamics under downburst and typhoon were discussed. The results from the present study highlighted the significant transient nature of the downburst wind and its transient effects on the indicial response function, aeroelastic loads and buffeting response, while negligible transient effects under typhoon events.