Coupled Three Degree of Freedom Motion Response of a Drydocked Submarine to Seismic Load

摘要

A mathematical model is developed to analyze the seismic response of a drydocked vessel in three degrees of freedom; vessel rotation about its keel and vessel horizontal and vertical translations relative to the drydock cradle. Data form eleven actual vessel-drydock systems and the time acceleration history of an earthquake are implemented to predice vessel three degres of freedom response during an earthquake. Vessel seismic response and the resultant drydock forces are compared to vessel-drydock system failure criteria to determine stability of the system during earthquakes. The three degree of freedom vessel response model is compared to a one and two degree of freedom vessel response models and a model in which seismic loading is simulated by a single static force. The three degree of freedom vessel motion is shown to be the most accurate method for analyzing vessel-drydock system failure criteria.