This paper aims to provide a simplified procedure for estimating the forces on piles and mooring anchor piles as foundations for offshore structures. A key step in this evaluation is calculation of the natural frequency of piles embedded in multi-layered soils. The piles may be mooring anchors or piles supporting subsea structures such as manifolds and are subjected to dynamic loads including earthquake loading. The solution is based on assuming the structure as a rigid mass on soil springs representing the stiffness of the pile at its pile head. The earthquake load is computed using the natural frequency and the acceleration response spectrum on the seabed. The paper also addresses the earthquake forces on anchor piles.
Amir A. Rahim and Amir M. Kaynia
Keywords: multilayered ground, pile, suction anchor, manifold, natural frequency, earthquake, dynamic stiffness
Publisher: DFI