Effect of Wave Spectral Variability on Stochastic Response of a Long-Span Bridge Subjected to Random Waves during Tropical Cyclones

Empirical single-peak wave spectra have been widely applied in current practice for the stochastic analysis of sea-crossing bridges under random waves. However, single-peak wave spectra may not be appropriate for evaluating the wave responses of bridges located in the nearshore site under tropical cyclones. In this study, typhoon wave spectra at an actual bridge site were measured and analyzed during Typhoon Dujuan in 2015. The stochastic structural responses of an example sea-crossing cable-stayed bridge under random waves were assessed by employing measured and empirical wave spectra. A frequency-domain approach was developed and validated with time-domain results as an efficient alternative for structural response analysis. The effect of wave directionality on the structural response was investigated and discussed as well. The main conclusions are: (1) the measured wave spectrum at the bridge site presents a double-peak shape and can be well described by the Ochi-Hubble spectrum; (2) the empirical Joint North Sea Wave Project (JONSWAP) spectrum may overestimate the internal force responses of the bridge towers and underestimate the displacement responses of the midspan; (3) the incident wave direction has remarkable impacts on the structural responses of the sea-crossing bridge and requires careful investigation; and (4) the proposed frequency-domain approach is an efficient as well as an accurate alternative for the long-duration evaluation of bridge responses.