Stochastic Inelastic Response of Offshore Towers to Strong Motion Earthquakes,

摘要

Complexities of stochastic analysis of offshore towers include nonlinear effects due to coupling of the hydrodynamic drag forces with structural response,non-linear effects due to hysteretic force deformation relations to the tower,and non-stationary random excitation and response. They are overcome by introducing certain approximations not affecting the numerical results seriously. Semi-closed form solutions are derived for the time dependent variances of response. Passing shot noise through a second order linear filter simulates ground acceleration. Internal tower forces are generated using linear and bilinear hysteretic relations,resulting in a full stiffness matrix where the tridiagonal terms are time dependent to account for hysterectic effects. Finally equivalent linearizations lead to a system of first order nonlinear diffenential equations with the time dependent variances of response as the unknown,which are determined as solutions of the differential equations. (Author Modified Abstract)