Earthquake response of solitary slender freestanding intake towers

Earthquake response of solitary slender intake towers is investigated considering an idealized hollow intake tower with its circular footing submerged in water. The tower is studied in anchored (fixed base) and unanchored (freestanding) states placed on undeformable soil foundation. The water-structure interaction is modeled by the Eulerian-Lagrangian approach, using the pressure-based elements for the water and the displacement-based elements for the structure. The only source of nonlinearity is the contact at the base joint between the tower's footing and the ground. This contact is modeled using Coulomb friction model which allows the tower to slide and uplift. The system is three-dimensionally analyzed using finite element method under static and dynamic earthquake loads. A detailed parametric study is conducted to assess the importance of system characteristics including surrounding and inside water levels, ratio of tower height to footing radius, base joint friction coefficient, water compressibility, footing flexibility, and vertical ground motion.