Time domain simulation of a floating bridge subject to the joint actions of an earthquake and wave actions

In this study, a numerical model called Python–OpenSeespy–Capytaine (Py–Op-Ca) was subjected to the seismic-hydrodynamic coupling effect. First, the theoretical model was investigated, including the equations of motion, solution of the wave force for a three-dimensional structure of an arbitrary shape, and construction of the numerical analysis model. Subsequently, to verify the accuracy of the proposed numerical model through a scaled geometric experiment, a conceptual floating bridge in the “E39” project in Norway was used as a reference structure, considering the effects of pure waves and joint effects of earthquakes and waves. Next, the dynamic response, diffraction, and radiation problems of floating structures under multiple hazards are discussed. The results indicate that the dynamic responses obtained from Py–Op–Ca agree well with the corresponding experimental values. A delay is observed in the time required for the sway displacement of the pontoon near the fixed end to reach its maximum amplitude. This delay effect gradually stabilized as the wave period increased, stabilizing at approximately 2.5 s. The earthquake ground motion propagating from the fixed end slightly increased the time of stabilization, reaching approximately 3.0 s.