Vertical Vibration of Floating Piles

An approximate analytical solution is presented for the vertical dynamic response of a floating pile. The dynamic stiffness and damping of the soil-pile system are also obtained. The results are compared with experiments. It appears that the motion of the tip cannot be neglected unless the pile is extremely long or the tip rests on rigid bedrock. The motion of the tip reduces the stiffness and increases the damping. With increasing length, the stiffness of a floating pile increases, while stiffness of an end bearing pile decreases. The damping of a floating pile is larger than that of an end bearing pile of equal length. Consequently, the dynamic response of a footing can be much smaller with floating piles than with end bearing piles. The relaxation of the tip improves the agreement between the theory and experiments.