Abstract: A new method called direct eigensystem realization algorithm (DERA) is developed for structural modal parameter identification. A direct procedure is presented for obtaining the minimum realization of a multiple-input multiple output time-invariant discrete system from observations of the input and output in time domain, and then modal parameters are obtained from the eigenvalues and eigenvectors of the system transition matrix. Because of the use of direct input-output observations, some weaknesses of the ...