Experimental Investigation of Primary-Secondary System Interaction

Keywords: Primary-Secondary System Interaction, Dampers, Shaking Table Simulation, and Seismic Excitation.

Abstract: A series of experiments were conducted on an earthquake simulator, whereby single degree-of-freedom pendulums (dampers) representing a secondary system were attached to the floor of a scaled, three-story frame representing the primary structure. The dampers had mass ratios ranging from one-tenth to one-hundredth with respect to the mass of the story to which they were attached. Both tuned and de-tuned cases were examined. Two types of excitations were imparted from the earthquake simulator to the frame with an attached damper, namely, white noise for identification purposes and the El Centro 1940 accelerogram. The results of these tests are grouped into transfer functions resulting from the white noise excitation and time histories resulting from the El Centro 1940 accelerogram. These results are followed by interpretations using numerical techniques developed previously for this purpose. Good correlation between the experimental evidence and the theoretical predictions is obtained, which points to the fact that interaction between primary and secondary systems does occur and can be detected.