| || Nonlinear seismic response of articulated offshore tower
Author : Islam, Nazrul;Ahmad, Suhail
Source : Defence Science Journal ; Vol:53(1) ; 2003 ; pp 105-112
Subject : 551 Geology;624 Civil Engineering
Keywords : Articulated offshore tower;Earthquake loading;Seismic response;Random vibration;Base shear;Nonlinear dynamics;Drag
Abstract : The seismic response of articulated offshore tower has been investigated by the spectral analysis method which is based on the principle of random vibration, where seismic excitation is assumed to be a broadband stationary process. The nonlinear dynamic equation of motion is derived using Lagrangian approach and the solution is obtained by Newmark's ß integration scheme. The present study includes nonlinearities associated due to variable submergence, drag force, Coulomb damping, variable buoyancy, and added mass along with the geometrical nonlinearities of the system. The study includes the joint occurrence of waves and seismic forces together with the current under random sea state. A parametric study has been conducted to investigate the relative importance of the seismic response in comparison to the response due to wave forces.