FREE VIBRATION ANALYSIS OF DOPLPHIN

When several pile butts are attached to a common structural element termed a pile-cap system, such a system in which piles are partially embedded in soil and is a fixed marine structure is called dolphin. Free vibration analysis of a real dolphin consisting of ۲۸ piles (both vertical and battered) capped in a massive concrete cap is carried out in order to ascertain its fundamental period of vibration. Therefore the objective of the present work is to study the feasibility of using SAP-۹۰ software to model dolphin behaviour using solid elements for cap, and spring supports for pile heads. From the study it has been observed that, use of spring supports with ۶-DOF to distribute the lateral loads among the pile heads in a dolphin is adequate and the fundamental period of vibration of the system was found to be ۰.۱۶۲ .seconds which proves that the proposed system is stiff enough for large impulsive impact forces due to very large capacities of ship (i.e., ۳۰۰,۰۰۰ DWT).