Dynamic response analysis of an offshore platform due to seismic motions

A three-dimensional (3D) numerical model for dynamic response analysis of seismic-induced motions is developed using the modal analysis and substructure methods. The developed model and an impedance function method are applied to an offshore platform with a pile–soil foundation system. The Newmark β method is used as a time integration scheme. The displacement and bending stresses at selective nodal points on the structure are computed for various maximum seismic accelerations and the shear-wave velocities of soil. Using a reliability index obtained by the Monte Carlo Simulation method, we successfully performed a reliability evaluation at the critical points of the structure for various seismic motions and soil conditions.