A proposal is presented for data condensation of long term signals. The purpose of the condensation is to obtain a short one or two minute dynamic force signal. The short signal can be applied to a finite element model (FEM) in order to compute the dynamic stress trace at any point in the structure. The fatigue damage produced by the short signal creates essentially the same damage per hour as the long signal. The structural component simulated in the study is a lattice dragline boom. Forces acting at the boom point transform into stresses throughout the lattice.