Seismic Performance of TMDs in Improving the Response of MRF Buildings

In this paper, the eectiveness of Tuned Mass Dampers (TMDs) in controlling building structures
under earthquake excitations is studied through investigating the practical considerations and
vibration control eciency of tuned mass dampers for 5-, 8-, 10- and 15-story buildings utilizing
a structural system with special Moment-Resisting Frames (MRFs) in both directions. Assuming
its frequency to be near the 1st natural frequency of buildings, it is designed to control the
largest response of the buildings. The eect of detuning, on some TMD parameters, on the
seismic performance is studied through time-history analysis using the El Centro and Tabas
earthquake records. In addition, the results of time-history analysis are compared with those of
a response spectrum analysis for the structures with and without TMD, in order to judge its
eectiveness. Under earthquake excitation, the performance of structures having TMDs greatly
depends on the characteristics of the ground motion. When the rst mode of a MDOF structure
dominates the structural response, a seismic response reduction can be easily achieved. While
the rst mode response of a structure with TMD is proved to be substantially reduced, the
higher mode response, in fact, increases as the number of stories increases. It is observed that
TMD is eective in reducing maximum displacement in MRF buildings by as much as 32.2%
in the Tabas earthquake and 45.3% in the El Centro earthquake. The maximum displacement
results of a response spectrum analysis for the uncontrolled and controlled case in the El Centro
earthquake, in an 8-story structure, are 25.70 cm and 14.59 cm, respectively, whereas the
maximum displacement using time-history analysis, in the uncontrolled and controlled cases,
are 27.54 cm and 15.14 cm, respectively.