Numerical simulation and analytical modeling of pile-supported structures subjected to ship collisions including soil-structure interaction

Most of the pile-supported protection structures were designed by empirical and static analyses to resist ship impact loading. Limited studies were carried out to reveal the failure modes and the dynamic interaction process of the pile-supported structures subjected to ship collisions. To clarify these issues, high-resolution finite element models of the ship-structure-soil interactions are developed in this paper. Several modeling issues (e.g., material model, artificial boundary and stress initialization) are discussed herein to ensure the rationality of the numerical models. Numerical simulations indicate that the platform and the connection of the protective system should be carefully designed to prevent their brittle failure besides providing the piles with enough ductility. Four interaction phases (i.e., initial contact, loading with approximate velocities, unloading and free vibration) are clearly identified for the overall flexural failure of the pile-supported structures. To efficiently predict the collision-induced responses, an analytical model with two-degree-of-freedom is proposed based on the high-resolution simulation observations. Methods of determining the equivalent mass and the force-deformation relationship involved in the analytical model are discussed in detail. The dynamic responses obtained from the analytical model are compared with the high-resolution FE results. It is found that the proposed simplified model is reasonable and efficient.