This award enables U.S. and Japanese researchers to collaborate on the design of smart base isolation experiments to be conducted using Japan's Earth Defense (E-Defense) shake table facility in Miki, Japan. This effort is time sensitive as Japan's National Research Institute for Earth Science and Disaster Prevention has recently committed the resources for these experiments, with high-level conceptual design to be completed during April through June 2011, followed with analysis and simulations completed by August 2011. Further design and detailing will occur next fall and winter, construction in 2012, and testing in late 2012 or early 2013. Japanese/E-Defense researchers plan to test the seismic performance of a three-to-four story, three-dimensional asymmetric reinforced concrete superstructure that incorporates different smart base isolation systems. In addition to linear rubber bearings in the isolation layer, tests will incorporate semi-active controllable damping devices to explore their potential for improving seismic performance over a wider array of ground motions than is possible with conventional isolation (fixed systems), as well as consider other types of devices that U.S. researchers may propose. This bilateral collaboration brings together expertise in controlled base isolation and semi-active devices, as well as experimental design and execution, so that both countries can maximize benefits from the experiments. The impetus for the experiments and the opportunities for this international collaboration were fostered in joint NEES/E-Defense planning meetings in 2009, 2010 and 2011 and is the outcome of the joint NEES/E-Defense Isolation and Control Working Group. This award supports several U.S. researchers to travel to Japan to work directly with E-Defense researchers on the design of the smart base isolation experiments, including superstructure, isolation system strategies, instrumentation, and post-test analyses. This award also supports the necessary design analyses and simulations to make experimental design decisions.
The planned E-Defense experiments of a base isolated structure with semi-active controllable damping devices are unique and provide a one-time opportunity for U.S. researchers to participate in full-scale experiments that currently cannot be conducted in the U.S. These E-Defense experiments will enable researchers to investigate and calibrate the level of seismic performance achievable with controllable dampers by extending isolation effectiveness to a much broader array of ground motions than possible with current conventional isolation technology. The tests will be the first laboratory experiments of magnetorheological fluid dampers at this scale for base isolation. This award will foster new research collaboration between NEES and E-Defense, as well as build new ties between U.S. and Japanese researchers. The experimental designs and resulting data will be disseminated to the research community via an already-established NEEShub group (http://nees.org/groups/isolationcontrol).