US-Japan Planning Visit for Complementary Experimental Programs Toward Validated Advanced Damping Systems

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This planning grant will establish complementary experimental programs between US and Japanese researchers to improve seismic damage mitigation in light of lessons of the 2011 Great East Japan Earthquake. This earthquake produced the most devastating long-period/long-duration ground motions ever recorded. These motions led to large displacements in structures previously thought to be safe, including high-rise buildings and base-isolated structures. A collaboration will be developed between the PI and Dr. Kohju Ikago of Tohoku University, taking advantage of the experimental expertise of PI in the area of real-time hybrid simulation (RTHS) and the structural control device advances of the Ikago Lab. The collaboration will investigate new supplemental control devices and control algorithms, experimentally evaluated using both shake tables and RHTS. The planning visit will open the door to the development and validation of new devices that are robust to wider range of ground motions, improving the seismic design of civil infrastructure and increasing resiliency under a broader class of earthquakes. Two US students will also receive training under the grant.Semi-active devices have great potential in mitigating structural damage from ground motion; they cannot destabilize the structural system, offer similar durability as passive devices, and can adapt to a wide range of input characteristics. This investigation into new semi-active control systems will be coupled with experimental testing using both shake tables and RTHS. RTHS offers a cost-effective tool to explore a wide variety of structural configurations through easily swappable numerical substructures. However, new considerations must be taken into account before RTHS can be used for the proposed long-period/long-duration ground motions. Also, shake table tests are widely accepted due to their simplicity while RTHS is a relatively new experimental testing framework that requires extensive validation before it is accepted by the engineering community and industry. RTHS will benefit from rigorous benchmarking in parallel with shake table studies. Through this partnership, structural control devices and control algorithms will be re-envisioned to accommodate a wide range of ground motions. The proposed research will include observing and participating in shake table experiments on small-scale structural control devices at Tohoku University, RTHS of small-scale devices (the same devices as explored in shake table testing), and establishing long-term working agreements and plans for incorporating testing and development at Maryland. The capacity of the research community will be enhanced by hardware, software, and algorithm development. The planning visit is expected to lead to a longer term collaboration to develop (1) control algorithms robust enough to include long-period/long-duration ground motion, (2) new devices aimed at a broad array of ground motion characteristics, (3) new RTHS capabilities, and (4) improved understanding of how to mitigate damage to high-rise and base-isolated structures from long-period/long-duration ground motion.