9503200 Villaverde To augment the damping of a structure significantly through a tuned-mass damper one has to use a damper with a large mass. A possible way to avoid the use of an additional mass is to use the building roof as the damper's mass. For this, one has to isolate the roof from the rest of the building, connect it to a spring and a dashpot, and then connect these to the rest of the building. More conveniently, however, one can take advantage of the progress made in base isolation technology and use elastomeric bearings instead of springs. The purpose of the proposed research is to conduct a numerical study with an actual building and an experimental study with two small-scale five-story steel building models to demonstrate that such a configuration is a viable way to construct a damper, to augment the damping in a building, and to increase its resistance to earthquake excitations. The numerical study will be carried out to investigate the bearing dimensions needed to attain the desired effect in a real building, the order of magnitude of the displacements experienced by its bearings, the behavior of the building-damper system when the structure is stressed beyond its elastic limit, and the design difficulties in implementing a real building with such a technique. The experimental study will be performed by testing on a shaking table the two building models. One of the models will be built with a conventional configuration and the other according to the proposed one. This study will serve to verify the findings from the numerical one without the assumptions and uncertainties involved in the analytical modelling of the building and its elastomeric bearings. The results of the studies are expected to demonstrate numerically and experimentally the viability and effectiveness of the proposed technique, will clarify some of the questions posed by its use, and, if proven effective, will furnish incentives, the justification, and the needed information for the planning of a large-scale experimental program. ***
