Underwater shaking table tests of a sea-crossing cable-stayed bridge under combined earthquake and wave action

Sea-crossing cable-stayed bridges may encounter the combined effects of earthquakes, waves, and currents, seriously threatening their service safety. In this paper, the effects of the combined earthquake and wave action on the dynamic responses of a sea-crossing cable-stayed bridge are investigated through underwater shaking table tests. The coordinative similitude law is adopted to fulfil the similarity of hydrodynamic and wave force. The test results indicate that, the combined action of earthquake and wave has significant effects on the dynamic response of the bridge tower, while the effects vary with the height of the tower and the type of ground motion. The side pier exhibits greater dynamic responses at the same loading cases and is more susceptible to the combined earthquake and wave action than the auxiliary pier. On the whole, in comparison to earthquake excitation alone, the combined earthquake and wave action significantly enhances the dynamic responses of sea-crossing cable-stayed bridge in most cases, with a maximum magnitude up to 20%–30%. By comparing with previously conducted underwater shaking table tests of substructures, the effects of water-structure interaction on the full cable-stayed bridge and bridge tower foundation are close, both of which are obviously lower than the effects on bridge pier.