ABSTRACT
Offshore platforms are free-floating, anchored, and bottom fixed by means of piled foundations or supported on massive or thick foundation slabs (or mats or spud cans). Some of these platforms are shown in Figure 4.1 [1]. Interaction and load transfer occur between the structural foundations and the seabed soil since the structures are supported over the soil through the foundations, and the static/dynamic forces applied/generated on the structure are transferred to the soil below through this interaction process. If the structure is supported over a stiff soil, the interaction effects between the soil and structure are much less, and the structure almost acts as if it is supported over a rigid bottom; whereas if the soil below is flexible, the interaction effects are much higher. Moreover, the structure supported over a flexible soil decreases its natural frequency, which, in turn, increases the dynamic response of the structure.
