Research

Standing strong against earthquakes - Researchers work to improve safety and peace of mind in high-rise buildings

Standing strong against earthquakes

In large cities where economic and administrative institutions are centered, the high-rise buildings that house these essential functions have become taller and taller. While the physical structures of these buildings may withstand an earthquake or other natural disaster, the work that takes place within may be disrupted for an extended period of time, paralyzing the social functions they provide. Such disruptions can have significant ramifications that extend throughout the nation and the world.

The Consortium for Socio-Functional Continuity Technology (SOFTech) was launched in the fall of 2017 to develop technology to ensure continuity of essential functions performed in high-rise buildings and other urban structures following a major natural disaster. This project was adopted by the Program on Open Innovation Platform with Enterprises, Research Institute and Academia (OPERA) as a Target-Driven R&D Project by the Japan Science and Technology Agency (JST). SOFTech comprises members from Tokyo Tech, Tohoku University, the University of Tokyo, and partners from industry.

We interviewed Professor Satoshi Yamada of the Laboratory for Future Interdisciplinary Research of Science and Technology (FIRST), Institute of Innovative Research (IIR), Tokyo Tech, about their activities. He is the chairperson of SOFTech.

Comprehensive solutions through five areas of research and developmentComprehensive solutions through five areas of research and development

What is SOFTech's vision?

Professor Satoshi Yamada
Professor Satoshi Yamada

Yamada: We are focusing on five areas of research and development to safeguard essential functions following major earthquakes or other catastrophic disasters affecting large cities.

1.
Develop and improve technology related to earthquake resistance, vibration control, and base isolation to secure the safety of structural systems. These are strong areas of interest at Tokyo Tech.
2.
Standardize performance verification methods for seismic devices and propose them as international standards. This is because full-scale testing has not been conducted on earthquake-resistant components intended for use in high-rise buildings.
3.
Advance development in earthquake resistance of nonstructural building components such as walls and ceilings. This is an area that has not yet been widely studied, but will have an impact on maintaining functionality within a building.
4.
Develop monitoring systems to quantify building safety and functionality. Researchers in various areas of sensor technology will play a central role in this effort.
5.
Identify ways to disseminate safety information to the public and ensure peace of mind. This is an area that has been largely neglected by researchers and technologists in the field, but is also critical to the safeguarding of essential functions. Because a breakdown of reliable information in large, densely populated cities increases the likelihood of panic and confusion, we have invited experts on the psychological and physiological influences of disasters to join in developing information dissemination methods to ensure people's safety and peace of mind.

Five areas of research and development
Five areas of research and development

Tokyo Tech, in particular, has been involved in 1. through 3. for some time and is considered a leader in these areas. Meanwhile, SOFTech plans to work on comprehensive countermeasures for natural disasters in large cities with a focus on the improvement of building structure functions, information collection by IoT and artificial intelligence (AI), and reliable dissemination of information to residents. These are the characteristic strengths of SOFTech. Furthermore, we strive for openness in our organization. Rather than limiting each area to a few select members, our researchers pursue multiple themes. We also periodically hold general research meetings and conduct joint experiments.

Can you tell us more about Tokyo Tech's involvement in SOFTech, particularly in relation to the university's strengths?

Yamada: The Urban Disaster Prevention Research Core at the IIR's FIRST, which is where I am, started from a group that conducted research on disaster prevention based on experience from the Great Kanto Earthquake of 1923. Through the Ministry of Education, Culture, Sports, Science and Technology (MEXT) Centers of Excellent (COE) Program and the Global COE (GCOE) Program, the former Tokyo Tech Center for Urban Earthquake Engineering (CUEE) works on the mitigation of large-scale disasters such as those we are seeing with increased frequency around the globe. As I mentioned before, because the impact is significant when urban areas are hit by natural disasters, we included "urban earthquake engineering" in the name. Japan, in particular, experiences frequent earthquakes, but continues to maintain functionality in metropolitan areas where the risk of damage is great. Therefore, Tokyo Tech researchers with extensive experience in urban earthquake engineering invited researchers at Tohoku University and the University of Tokyo to take part in applying to OPERA and participate in SOFTech.

Kazuhiko Kasai, co-chairman of SOFTech and specially appointed professor at FIRST, has worked on the international standardization of large-scale experiment devices used in the area of safety verification for seismic devices, which I mentioned earlier. He is an authority on high-rise buildings, base isolation, and vibration control technologies and has a long history of involvement in COE, GCOE, and other projects. With cooperation from Kasai and many other outstanding researchers, SOFTech promotes interdisciplinary collaboration to solve priority issues beyond the boundaries of individual universities and companies.

What are SOFTech's short-, mid- and long-term goals?

Yamada: Our short-term goal is to improve existing technologies related to earthquake resistance, base isolation, and vibration control. Furthermore, since the Great East Japan Earthquake, there has been a strong push to design buildings that, in addition to ensuring the safety of the occupants, also safeguard functionality and continuity of operations. High-rises and other large-scale structures in urban areas are also required to function as shelters during times of disaster. Therefore, we are prioritizing development of technologies to produce non-structural building components that are resistant to damage from natural disasters, thereby shortening the time required for recovery of essential functions.

Earthquake-resistant structure

Vibration control structure

Base isolation structure

Earthquake-resistant, vibration control, and base isolation structures

Has structural components, such as posts, beams, and walls, that absorb energy generated by an earthquake

Uses dampers to absorb energy generated by an earthquake, reducing vibrations and damage

Separates the base from earthquake vibrations

Damage to non-structural elements such as roofs and walls in the Great East Japan Earthquake
Damage to non-structural elements such as roofs and walls in the Great East Japan Earthquake

In regard to the development of building monitoring systems utilizing IoT and AI, we asked sensor manufacturers to join in our research from the planning stages, discussing basic matters such as accuracy and efficacy of sensor technology to develop the most appropriate device for a given purpose. This will enable us to evaluate the safety of individual buildings during times of disaster and, utilizing AI, provide appropriate information and evacuation guidance. This is of special importance if, for example, the elevators in high-rise apartment buildings stop operating. Such a situation would significantly impact elderly residents who are unable to use stairs unassisted. Residents also need to be informed on when to evacuate or remain in the building. In these and other cases, it is important that residents have reliable and timely information.

Our final goal is to standardize SOFTech research findings and export them overseas as total-package solutions. However, while Japan has accumulated highly advanced architectural technologies through its extensive experience with earthquakes, we have not yet fully shared our knowledge outside of Japan. We would like to make these technologies available on a global scale and establish a win-win relationship with other countries encountering natural disasters. We believe that doing so would be a significant social contribution to the world.

New Value to be created by SOFTech
New value to be created by SOFTech

Tokyo Tech's leading research in disaster preventionTokyo Tech's cutting-edge research in disaster prevention

Base isolation technology

Tokyo Tech has an impressive history in the development of base isolation technology. Leading this development is Akira Wada, professor emeritus at Tokyo Tech, representative director of the Japan Academic Network for Disaster Reduction, and president of the Japan Society of Seismic Isolation.

Bi-directional dynamic loading test on steel damper for base isolated buildings simulating behavior caused by earthquake.

Base isolation, which involves placing an isolation unit between a structure and the ground, is the most common means of protecting a structure from the direct vibrations caused by an earthquake. The isolation unit mitigates the impact of earthquake vibration to reduce damage to both the structure and facilities within it. A typical example of isolator is the rubber bearing. The oblong structure of high-rise buildings, however, may cause the rubber bearing, which would be placed at the edge of the base, to fracture with tensile force caused by overturning behavior. Application of rubber bearings is, therefore, generally limited to middle- and low-rise buildings. Tokyo Tech's J2 Building at Suzukakedai Campus is a rare example, in that it is equipped with a rubber bearing base isolation system despite being 20 stories tall. However, installed under Wada's guidance, the system is designed to allow uplift movement during major earthquake. J2 Building is proof of the capabilities of urban earthquake engineering at Tokyo Tech. At SOFTech, we plan to standardize performance test methods for large-scale base isolation units intended for high-rise buildings.

Tokyo Tech's J2 Building at Suzukakedai Campus
Tokyo Tech's J2 Building at Suzukakedai Campus

Vibration control technology

Professor Kazuhiko Kasai
Professor Kazuhiko Kasai

Vibration control is, as the name implies, technology designed to reduce vibrations during an earthquake. Vibration control units include hysteretic dampers, which absorb earthquake energy input through the deformation of metallic materials, as well as viscous and viscoelastic dampers that convert an earthquake's energy into thermal energy via oil and viscoelastic high-polymer materials. Evaluation of the performance of viscous and viscoelastic dampers must take vibration rate of the unit and temperature of the medium into account, as both influence performance. In addition, the surrounding parts and materials are load-bearing; therefore, the units must be installed in appropriate locations to be effective. This means that placement of vibration control units is a critical consideration in building design. However, individual buildings differ greatly, and for this reason, Kasai has worked to develop design guidelines and indicators, as well as methods to evaluate performance.

Dynamic performance verification experiment of vibration damper (buckling restrained brace) with loading speed corresponding with seismic behavior

大型部材の性能評価

Draft of tri-directional loading device
Draft of tri-directional loading device

Other issues remain regarding the materials used in high-rises and other large buildings, as well as those in base isolation and vibration control units. Kasai considers the most serious of these issues to be how high-intensity structural materials and large devices have been used without full-scale testing. High-intensity structural materials and vibration control units are essential for high-rise buildings; however, due to technical limitations, experiments are limited to the use of reduced scale models. This forces us to predict the performance of full-scale materials based on results from reduced scale models. This is clearly an obstacle in understanding the actual behaviors of large-scale materials.

To overcome this obstacle, SOFTech aims to develop a tri-directional loading device with the world's most advanced testing capabilities. In April 2017, the Advanced Loading and Real-Scale Experimental Mechanics Laboratory (ALREM) was established in collaboration with industry to conduct experiments using large-scale loading devices.

Kasai states, "The experiments will allow us to conduct performance tests forbase isolation units and vibration control devices, and would result in significant performance improvement. The use of such upgraded isolation unites and vibration control devices would lead to the high-rise buildings of next generation, the buildings with socio-functional continuity even after the major seismic attack. We are still in the early stages, so we are not receiving support from the government yet; however, we will continue working to increase our capabilities."

Focusing on people to mitigate damage from natural disasters

Associate professor Mitsue Nagamine
Associate professor Mitsue Nagamine

In line with SOFTech's fifth area of research and development, to ensure people's peace of mind, Mitsue Nagamine, an associate professor at Tokyo Tech's Institute for Liberal Arts (ILA) who specializes in psychophysiology, is working to identify ways of reducing the psychological effects of natural disasters on people working and living in high-rise buildings.

When a major earthquake occurs, the upper floors of a building are subject to severe vibrations, making it difficult for occupants to evacuate. People in the building may feel strong anxiety, which can increase the damage of a disaster on bodily as well as psychological impacts. Therefore, we are examining measures to reduce anxiety. One example is our study of the content and transmission of emergency information. We also monitor physiological effects, such as changes in heart rate and blood pressure, that people may experience when in a high-rise building during a disaster. This could help us to identify areas where people feel secure, which could then be applied in future development of high-rise buildings. Nagamine states, "Safety and peace of mind are different concepts. SOFTech is working to mitigate damage from natural disasters by improving hardware and to increase peace of mind by improving 'soft-ware.' As a soft-ware researcher, I cooperate with hardware researchers to facilitate urban development that ensures both people's safety and their peace of mind."

Participating organizationParticipating organization

Tokyo Institute of Technology

Satoshi Yamada

Professor
Institute of Innovative Research (IIR) Laboratory for Future Interdisciplinary Research of Science and Technology (FIRST)

Chairman

Shoichi Kishiki

Associate Professor
Institute of Innovative Research (IIR) Laboratory for Future Interdisciplinary Research of Science and Technology (FIRST)

Head of Division for Research Strategy, SOFTech

Kazuhiko Kasai

Specially-appointed Professor
Institute of Innovative Research (IIR)
Laboratory for Future Interdisciplinary Research of Science and Technology (FIRST)

Co-Chairman
Representative of Research Theme 2

Toru Takeuchi

Professor
School of Environment and Society

Head of Division for Education, SOFTech

Daiki Sato

Associate Professor
Institute of Innovative Research (IIR)
Laboratory for Future Interdisciplinary Research of Science and Technology (FIRST)

Head of Division for Communication, SOFTech

Hidemi Takahashi

Specially-appointed Professor
Office of Research and Innovation
Head of Division for IP Strategy

Head of Division for IP Strategy, SOFTech

Shojiro Motoyui

Professor
School of Environment and Society

Representative of Research Theme 3

Kentaro Nakamura

Professor
Institute of Innovative Research (IIR)
Laboratory for Future Interdisciplinary Research of Science and Technology (FIRST)

Representative of Research Theme 4

Tatsuya Yumiyama

Professor
Institute for Liberal Arts

Scenario creation

Mitsue Nagamine

Associate Professor
Institute for Liberal Arts

Scenario creation

The University of Tokyo

Jun Iyama

Associate Professor
School of Engineering

Head of Research & Development
Representative of Research Theme 5

Tohoku University

Masaki Maeda

Professor
School of Engineering

Head of Research & Development
Representative of Research Theme 1

Hiroaki Maruya

Professor
International Research Institute of Disaster Science (IRIDeS)
School of Law

Scenario creation

Private Companies

  • Kyushu Daiichi Kogyo Co., Ltd.
  • KYB Corporation.
  • KEN KEN Co., Ltd.
  • SHIMIZU CORPORATION
  • SWCC SHOWA CABLE SYSTEMS CO.,LTD.
  • NIPPON STEEL & SUMIKIN
    ENGINEERING CO., LTD.
  • Takenaka Corporation
  • TEIJIN FRONTIER CO., LTD.
  • The Japan Iron and Steel Federation
  • Human Environment Design Laboratory Ltd.
  • Fukuvi Chemical Industry Co., Ltd.
  • Bridgestone Corporation
  • OILES CORPORATION
  • Sumitomo Mitsui Construction Co., Ltd.

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Published: March 2018