Abstract
The dynamic response analysis of fixed offshore cylindrical shell structures subjected to earthquake ground motions is studied by using the free vibration data in water, which was already obtained by three different approaches; Rayleigh-Ritz method, finite element method and matrix progression method. The hydrodynamic pressures on a vibrating shell subjected to earthquake ground motions can be obtained as the sum of the pressure component due to rigid body motion of a shell and the pressure component due to elastic deformation of a shell by a linear potential flow theory. The effects of dynamic interaction between a shell and water are estimated as the added mass in phase with the acceleration of a shell, the radiation damping in phase with the velocity of a shell and the added applied force due to rigid body motion in water in the uncoupled modal equation of motion which can be derived by making use of the orthgonality of mode shapes in water. The response quantities such as displacements and stress resultants are obtained in the frequency domain and in the time domain. In order to show the application of the theory and the procedure, some numerical calculations are carried out. Based on the numerical results, the effects of shell configulation and water depth on the dynamic behaviours and the effects of radiation damping on the response quantities are discussed.
