INFLUENCE OF WAVE-SURGE-CURRENT CORRELATION ON WAVE AND CURRENT LOADS TO ELEVATED PILE CAP FOUNDATION OF BRIDGE UNDER TYPHOONS

Typhoon is one of the main disastrous weather systems in China. Huge waves, strong surges and rapid currents will be generated under the action of typhoon in the bridge site area, which will cause the elevated pile cap foundation of bridges bear huge wave and current loads. In extreme environments, the environmental parameters of waves, surges and currents are dependent on each other. The correlation of wave-surge-current is less considered in the existing design standards, resulting in a conservative design. In order to study the influence of wave-surge-current correlation on the wave and current loads to the elevated pile cap foundation of the bridge under typhoons, this paper obtained the wave-surge-current data under the actions of 49 typhoons based on the SWAN+ADICIRC model, and used the three-dimensional nested Frank Copula model to obtain the three-dimensional joint distribution of the wave-surge-current, and established environmental contours with 100-year return period. The wave and current loads were calculated using the potential flow theory and Morrison equation. The wave and current loads calculated with and without considering the wave-surge-current correlation were analyzed and compared. The research shows that: the wave and current load calculated considering the wave-surge-current correlation is 17.40% lower than that without considering the correlation; the wave and current load has an obvious positive correlation with effective wave height, spectral wave period and current velocity, but is not sensitive to the change of surge; after considering the correlation of waves, surges and currents, the combination of environmental conditions corresponding to the base shear and the mudline moment is no longer consistent.