Vibration control of steel frames with setback irregularities equipped with semi-active tuned mass dampers

This paper presents a pioneering study on the seismic vibration control of steel moment-resisting frames (MRFs) with setback irregularities using semi-active tuned mass dampers (SATMDs). The research investigates the efficiency and the location of the SATMDs and compares their efficiency with traditional tuned mass dampers (TMDs) for the vibration control of setback structures with different vertical irregularities. To assess the nonlinear seismic performance of buildings with setbacks, various engineering demand parameters such as interstory drift ratio, story displacement, story velocity, story acceleration, and base shear factor were analyzed under earthquake excitations. The results reveal that the use of SATMDs reduced the seismic response of irregular frames with setbacks. In addition, the efficiency of SATMDs in the control of setback frames was more than the regular frames. Also, the investigations showed that placement of the control systems at the roof level of the structure significantly reduced the structural vibration of irregular structures. It is noticeable that the use of these control devices requires more attention for structures with significant setbacks because, in some cases, the response of a structure with SATMDs can be greater than an uncontrolled structure.