Effects of partial structural damage in the dynamic characteristics of an existing RC building

Reinforced concrete buildings may experience partial damage after earthquakes or some human-induced actions. A decision about the future of those buildings requires detailed analyses, while determining the dynamic characteristics of a real building in its pre- and post-event situations can guide the analysis. Hence, this study was planned to monitor the dynamic response of an existing six-story, reinforced concrete building with regard to structural damage. The modal characteristics of the original building were initially determined by the use of operational modal analysis. Next, three steps of progressive structural damage were applied to the building. The first damage level peeled off the clear cover of a beam and three columns on a corner of the building's ground floor. whereas the second and third levels completely razed the damaged columns. Operational modal analysis was repeated at each damage stage to extract the frequencies and detailed mode shapes. Moreover, numerical models based on the finite element method were constructed to confirm the obtained experimental findings. The well-agreed experimental and numerical findings revealed the damage sensitivity of the building's dynamic response. The quantified amount of frequency change favored a retrofit of the partially damaged buildings rather than their replacement.