Estimation of airgap’s impacts on floating structures taking into account of second order non-linear corrections

Abstract

    Actual standard methods of predicting airgap demands for floating structures in early design stages which are mostly based on linear models still yield uncertainties and lack required reliability. This paper presents a research on the prediction of airgap responses and its impacts on floating structures (Semi-submersible, TLP...) based on the first order analysis in frequency domain using HydroStar (Research Department -Bureau Veritas, 2014). The "Stokes 2nd order correction" method proposed by (Bert Sweetman, 2002) is applied as a correction method to consider secondorder non-linear behaviors. The Hermite model of Steven R. (Winterstein, 1994) is also applied by programming in Matlab to determine the extreme values of second order responses (in addition to the conservative linear analysis by HydroStar software).
     All of the results are compared with Bert Sweetman's results (Bert Sweetman, 2002) and the model test data of the Veslefrikk B Semi-submersible by MARINTEK Trondheim, Norway (1995).