MODAL PARAMETER ESTIMATION OF A SMALLSCALE MODEL OF AN OFFSHORE PLATFORM : ACOMPARISON OF TWO DIFFERENT ALGORITHMS

Abstract

A modal parameter estimation algorithm using Programming, a nonlinear optimization technique, is presented. Some numerical simulations that reproduce complex practical applications were performed and the results estimated through Goal Programming algorithm are compared with those estimated through a classical modal estimation method - the Orthogonal Polynomials Method. Experimental tests were carried on a small scale model of a fixed offshore platform and the Frequency Response Functions (FRFs) obtained are analyzed using the Orthogonal Polynomials Method and Goal Programming algorithm. The Modal Assurance Coefficient (MAC) matrix is used to correlate the experimentally estimated mode shapes and the numerical ones, obtained through a finite element code. It is shown that the developed algorithm estimates modal parameters more accurately than the classical method does.