Hydrodynamic force model for free spanning submarine pipelines under earthquake

The earthquake input directions affect seismic response of free spanning submarine pipeline. A hydrodynamic force model improved from Wake model considering three dimensional excitation inputs is presented. Equations of motion are derived from the improved Wake model on the basis of finite element method. Finite element model is established to simulate the experimental conditions. The numerical results subjected to sine wave input and simulated El Centro earthquake input are obtained. The comparison of numerical and experimental results shows that the Wake model considering excitation directions could satisfactorily predict dynamic response of free spanning submarine pipelines under earthquake,and the numerical results are in agreement with the experimental ones.