Previous research by the authors has shown that adding steel zipper struts to a special concentrically braced frame can dissipate energy uniformly over the height of the building and limit the first-story collapses typical of braced frames. In this paper, the conventional steel zipper struts are replaced by active zipper struts, consisting of control actuators embedded within the zipper strut elements. These elements improve the dynamic performance of the structure when subjected to random external excitations. The active zipper struts apply forces to the frame to transfer the buckling-induced unbalanced vertical forces upwards or downwards according to force commands which are calculated on- line by means of a Sliding Control algorithm. This paper presents the derivation of the dynamic equations for the structural system including the active control system. A one-story braced frame with a single input control system under pushover and earthquake loads is studied numerically to demonstrate the viability of the active zipper struts concept. The studies show that the control system is robust and can significantly reduce interstory drifts, resulting in improved seismic performance for the structure.
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