Risk Evaluation and Disaster Mitigation Research Division
Earthquake Engineering Lab

Concurrent: Graduate School of Engineering
Research Subject(s)
Our research topics include:
1. Development of novel seismic protective systems for civil strucutres
2. Rate-independent linear damping for effectively reducing excessive displacement in low-frequency structures
3. Structural health monitoring
4. Advanced structural experiment technologies
5. Inverse variational principle
Key Words
Earthquake Engineering / Structural Optimization / Structural Control and Health Monitoring / Seismic Protective Systems / Inerter
Research Activities

We develop innovative and high-performance seismic response control devices for civil structures to ensure higher earthquake resistance of civil structures against future-expected extreme seismic events such as the Nankai Megathrust Earthquake.

We successfully develop an inerter-damper device that achieves more than 7,000 tons of apparent mass with a physical mass of 800 kgs. A tuned mass damper-like system designated the tuned viscous mass damper comprises the inerter-damper device and a tuning spring element, which is utilized in several high-rise buildings in Sendai and Tokyo.

Torsional collapse of high-rise buildings is explored. Bifurcation of asymmetric torsional deformation can occur in a high-rise steel moment resisting frame when subjected to a massive earthquake even if it has symmetric plan and very small eccentricity. Countermeasure technologies to prevent this phenomenon is persued.

Selected Works

Kohju Ikago, Kenji Saito, Norio Inoue (2012) Seismic control of single-degree-of-freedom structure using tuned viscous mass damper, Earthquake Engineering and Structural Dynamics, 41; 453-474., doi:10.1002/eqe.1138.

Kohju Ikago, Yoshifumi Sugimura, Kenji Saito, Norio Inoue (2012) Modal Response Characteristics of a Multiple-Degree-Of-Freedom Structure Incorporated with Tuned Viscous Mass Dampers, Journal of Asian Architecture and Building Engineering, 11(2);  375-382.

Takehiko Asai, Yoshikazu Araki, Kohju Ikago (2017) Energy Harvesting Potential of Tuned Inertial Mass Electromagnetic Transducers, Mechanical Systems and Signal Processing, 84; Part A, 659-672.

Ruiyang Zhang, Brian M. Phillps, Shun Taniguchi, Masahiro Ikenaga, Kohju Ikago (2016) Shake table real-time hybrid simulation techniques for the performance evaluation of buildings with inter-story isolation, Structural Control and Health Monitoring, 24(10); 2016; e1971; DOI:10.1002/stc.1971.

Takehiko Asai, Yoshikazu Araki, Kohju Ikago (2018) Structural control with tuned inertial mass electromagnetic transducers, Structural Control and Health Monitoring, 25(2); e2059, DOI: 10.1002/stc.2059

Selected Memberships
  • Architectural Institute of Japan
  • American Society of Civil Engineers
  • Japan Association for Earthquake Engineering
  • The Japan Society of Seismic Isolation
  • Japan Structural Consultants Association
Selected Awards
  • Best Paper Award 2012, Journal of Asian Architecture and Building Engineering (JAABE), 2013. 2.
  • 2015 Architectural Institute of Japan (AIJ) prize for the book "Displacement Control Design of Buildings" written by Profs. N. Inoue and K. Ikago.
  • Best Reviewer Award 2017, Japan Society for Promotion of Science (JSPS).