A refined FDD algorithm for Operational Modal Analysis of buildings under earthquake loading

An autonomously-developed, refined Frequency Domain Decomposition (FDD) algorithm implemented within MATLAB is applied to the modal dynamic identification of civil frame buildings subjected to a set of strong ground motions. The performed research deals, as a necessary validation condition, with pseudo-experimental signals generated prior to the dynamic identification, from the numerical response of several shear-type frames. Strong motion modal parameters are then extracted and estimated successfully at given seismic input, taken as base excitation. Results turn-out very much consistent with targeted values, with quite limited errors in the modal parameter estimates, including for the modal damping ratios, ranging from low to high values. Notice that seismic excitation responses shall not fulfill traditional input assumptions of FDD techniques. This highlights the consistency of the present refined FDD algorithm in such a challenging framework. This paper shows that, in principle, a comprehensive modal dynamic identification of frame buildings through a refined FDD algorithm looks possible at seismic input.