10-04-2013, 11:21 AM
SEISMIC ISOLATION FOR SOFT-STORY BUILDINGS
Author: Seval Pinarbasi , Dimitrios Konstantinidis , James M. Kelly | Size: 0.2 MB | Format: PDF | Quality: Unspecified | Publisher: 10th World Conference on Seismic Isolation, Energy Dissipation and Active Vibrations Control of Structures, Istanbul, Turkey, May 28-31, 2007 | Year: 2007 | pages: 12
Reconnaissance reports following strong earthquakes time and again point to the widespread
damage caused to buildings with soft stories. This study is motivated by the need to provide
mitigation strategies for these types of structures. There exists a general belief among
practicing engineers that seismic isolation can only be effective in reducing the seismic
demand for regular, uniformly stiff buildings but not for soft-story buildings since it is
thought that the flexibility of the soft story deems the isolation ineffective. This paper
present results from an extensive numerical investigation that dispels this misconception. It
looks at the results of modal and nonlinear time-history analyses conducted on simplified
models of a hypothetical five-story reinforced concrete building with a soft ground story to
draw conclusions on the efficiency of seismic isolation as the flexibility of the soft story is
increased. Comparison is made with how soft-story flexibility affects the corresponding
fixed-base building. Practical ways, if necessary, for increasing the efficiency of the
technique is also examined, showing that it benefits greatly by stiffening the soft story.
Success of the linear theory developed for base-isolated structures in predicting the basic
response parameters (both modal and seismic) when the structure has a soft ground story is
also assessed. The paper confirms that seismic isolation can be used as a viable mitigation
technique for soft-story buildings.
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