Output-only modal parameter estimation of structures by enhanced frequency domain decomposition method

In recent years output-only modal identification or operational modal analysis (OMA) has gained great attention of engineers. In the context of OMA, there is no need to measure the input and the modal parameters of dynamic systems are estimated just based on the output response. One of the most popular and robust frequency domain methods of OMA is Enhanced Frequency Domain Decomposition (EFDD). Identification process in this technique is based on the singular value decomposition of power spectral density matrix of the structure output. In spite of the high reliability, EFDD still faces several limitations and some parameters should be chosen by researcher. We aim in this paper to evaluate the reliability of EFDD in modal parameter estimation (natural frequencies, mode shapes and damping ratios) and clarify its merits and demerits. By a simulated 5 story shear frame, performance of EFDD is evaluated for different modal damping ratios. Moreover, influence of measurement duration on estimation process is assessed. Since, the noise is always inserted in the measurement; real data of Heritage Court Tower was utilized to illustrate the capability of EFDD in the presence of measurement noise.