Integrated assessment of the hydrodynamic added mass of the deep-water pile-cap foundation considering pile group - pile cap interaction

The earthquake-induced hydrodynamic effect on the elevated pile-cap foundation is distinct from the immersed single columns or piers due to the pile group - pile cap interaction. This paper focused on the hydrodynamic added mass of the pile cap and pile group in the elevated pile-cap foundation submerged in water. The potential-based numerical model of the added mass for the integrated elevated pile-cap foundation was developed and verified with the existing solutions of added mass for the pile group. The added mass of an example deep-water elevated pile-cap foundation was calculated by the developed model, and compared with those of an isolated pile cap or pile group. The effects of pile group - pile cap interaction on seismic responses of the example foundation were quantified. It is found that the interaction can increase the added mass of the pile cap, while the interaction has a minor impact on the added mass of the pile group. Neglecting the influence of the pile group - pile cap interaction will not increase prediction errors for the structural seismic responses. The developed model allows a better understanding of the hydrodynamics of the elevated pile-cap foundation submerged in water under earthquake loading.