| The majority of the existing infrastructure, designed prior to the enactment of modern seismic codes, is seismically deficient. Because it is not feasible to replace the entire inventory of seismically deficient infrastructure with new and seismically designed infrastructure, retrofitting remains to be the only viable option for seismic risk mitigation. Therefore, there has been significant research on the development of seismic retrofit technologies. The research project reported in this thesis is an effort towards developing a new seismic retrofit technique that utilizes pulse-based active force control. This approach involves the monitoring of structures during a seismic event and applying control forces through actuators beyond an acceptable range of deformations to minimize lateral drift and hence the potential structural and nonstructural damage.;The research project involves tests of small-scale frames on a shake table, with and without active force control. Two single-storey single-bal frames were manufactured for this purpose, with two different stiffnesses. Different magnitudes of mass were placed on the frames as part of experimental parametric investigation. The changes in stiffness and mass resulted in different vibration frequencies. Idealized ground motions in the form of sinusoidal wave functions were applied at different frequencies to assess the relationship between the dynamic characteristics of the structure and those of the ground excitation. A previously recorded earthquake record was also used to investigate the feasibility of the retrofit technique under realistic seismic excitations. The results indicate that pulse-control can be used as an effective methodology for seismic risk mitigation. The seismic drift was reduced between 65% and 95%, and the structural performance improved significantly. The control forces remained relatively low, indicating that it is possible to apply the techniques in practice, at full scale. |
