In this paper, modal identification results of half-scale, single-bay, single-story three reinforced concrete (R/C) frames with different infill conditions are presented. The frames were tested along their in-plane directions under gradually increasing quasi-static cyclic loading. At each predetermined drift level, ambient vibration and white-noise tests were conducted on the frames for the purpose of identifying their modal parameters. The modal identification results are correlated with detailed visual damage inspections. This paper aims to investigate (i) the evolution of the estimated modal parameters as a function of increasing structural damage, (ii) the performance of various output-only system identification methods in identifying modal parameters of damaged frames, (iii) the identification results obtained by using different excitation types having different amplitude levels, and (iv) the influence of different types of infills on the induced damage, and therefore to assess the effects of increasing infill damages on the modal identification results.
