Experimental Investigation on the Performance of Tuned Mass Damper Embedded on Steel Frame under earthquake excitation and Estimation of the Modal Parameters

Tuned mass dampers (TMDs) are being increasingly used for protection of structures against seismic and environmental loads. An important step in design and application of TMDs is the evaluation of TMD parameter which can cause be associated with serious difficulties. In this paper, we attempt to provide a framework to evaluate the modal parameters of TMDs using a combination of experimental test on shake table and a relatively recent modal analysis technique, namely Frequency Domain Decomposition (FDD). In order to achieve this, a series of test were conducted on a 5-storey steel frame was subjected to excitations from two scaled earthquakes (Imperial Valley and Kobe) ) while damped using two TMDs with mass ratios of 0.01 and 0.1.Mounted instrumentations recorded the structural response during the earthquakes and the recorded response was then used for an operational modal analysis (OMA) in order to estimate the dynamic characteristics of the TMDs. The FDD technique was used in this paper which was employed to estimate the parameters of TMDs. The damping ratios obtained from FDD method was compared with classical methods to verify its accuracy and capabilities in extraction of the modal parameters of TMDs. This paper shows that the use of shake table experiments coupled with the post-experiment modal analysis can be successfully used in TMD design and enables the researchers and practitioners to accurately estimate and test the response of the structures under relatively realistic conditions, which consequently allows low-cost testing of TMDs for optimum TMD selection.