dynamic response of rocking structures equipped with vertically mounted viscous dampers in bottom story

Earthquake ground motions impart kinetic energy into structures. by reducing this energy, the location and the extent of the damage are controlled.reducing seismic response may be obtained by allowing part of the structure to lift during large horizontal ground motions. this mechanism is referred to as uplift or rocking, and involves a discontinuity of contact between part of the foundation and the soil beneath, or between a vertical member and its base. in reality, foundations are not firmly bondedto the soil underlying the structure, and supported on the soil only through gravity forces. whether the assumption that the foundation and soil are firmly bonded is considered or not, uplifting would occur during an earthquake to an extent. the good performance of some pre-code low-rise brittle concrete buildings in the near-fault region of the hawke’sbay, new zealand, earthquake of 1931 can only be explained by rocking having beneficially occurred during the earthquake. while not incorporating any energy dissipaters, these buildings relied solely on uplifting columns or rocking of foundations to produce the desired effects.