A New Damage Detection Method for Aging Offshore Platform Using Two Measurements

Abstract

A new damage assessment method is proposed for aging offshore platforms based on dynamic tests. The stiff nesses of the measured model corresponding to the two measurement moments are estimated by a series of stiffness-correction factors, respectively. Based on these stiffness-correction factors a new damage indicator is defined aiming at reducing influences of existed damages accumulated before the first measurement on damage assessment occurred between the two adjacent measurements. One theoretical improvement is that the requirement using the stiffness matrix of FEM to replace the one of the measured model can be ignored in the calculation of MSE of the measured model. The other development is influences of damages accumulated before the first measurement on damage detection occurs between the two measurements could be reduced greatly, which is very important for aging platforms because these platforms have not been tested aiming at damage detection during their previous service life, especially for most platforms in China. A jacket platform is chosen for numerical studies, and numerical results show that the proposed method could identify damages occurred between the two measurements properly, even including damage severity estimation.