NATIONAL SCIENCE FOUNDATION
TOKYO REGIONAL OFFICE

The National Science Foundation's (NSF) Tokyo Regional Office periodically receives and disseminates reports on research developments in Japan that are related to the Foundation's mission. It also provide occasional reports on developments in other East Asian Countries.

These reports present information for the use of NSF program officers and policy makers; they are not statements of NSF policy.

Special Scientific Report #03-01 (May 16, 2003)

Summary of Joint Initiative

The 5-year U.S.-Japan Cooperative Research in Urban Earthquake Disaster Mitigation initiative was supported by the U.S. National Science Foundation (NSF) and the Japanese Ministry of Education, Culture, Sports, Science and Technology (MEXT). The research initiative was driven by two major factors:

(1) The urgent need to accelerate knowledge and design concept development in order to reduce urban earthquake damages and losses. The urgency was created by two disastrous urban earthquakes: the Northridge California Earthquake in 1994, which resulted in a total economic loss over $40 Billion and the Kobe Japan Earthquake in 1995 with a gross loss figure of $100-200 Billion.

(2) Accelerated development of new technologies (in control, sensors, IT, etc.) that promised to add new dimensions to traditional engineering approaches in protecting structures from damage, to disaster management, and to approaches for reducing losses caused by earthquakes.

This joint initiative complemented the eminently successful joint U.S.-Japan Cooperative Research Program on Large-scale Testing, that has been on-going since 1980 under the technical direction of Professor J. Penzien (University of California, Berkeley) and Dr. M. Watabe (formerly Building Research Institute, Tsukuba, Japan), and the equally successful 5-year joint research initiative on Structural Control for Performance, Safety and Hazard Mitigation (NSF91-62), which was implemented under the technical guidance of Professor G. Housner (Caltech) and Professor T. Kobori (Kajima Corporation, Japan). The Urban Earthquake initiative represented the first NSF-MEXT partnership offering long-term (5-year) support for cooperative research in earthquake engineering and hazard mitigation. The initiative covered five thrust research areas: social science systems, geotechnical engineering systems, advanced steel structures, performance-based engineering and design, and advanced technologies.

A Joint Technical Coordination Committee (JTCC) was established to provide direction for the initiative, to organize forums for technical and data exchange, and to appraise progress. Professor Mete Sozen of Purdue University, who is the U.S. co-chair of the JTCC, maintains a website (http://bridge.ecn.purdue.edu/~vail/jtcc/) for distribution of information related to Urban Earthquake initiative activities and research.

The NSF program announcement for the Urban Earthquake initiative (NSF 98-36) can be found at http://www.nsf.gov/pubs/1998/nsf9836/nsf9836.htm. NSF awards in support of the initiative were made in fiscal years 1998-2002. NSF completed five rounds of proposal competition and supported a total of 48 excellent proposals (see tables below) selected through the peer review process. NSF funding for the 5-year initiative totaled $6.76 million.

Major accomplishments made possible through the synergistic collaboration of U.S. and Japanese researchers include the following.

• The consensus of researchers in strong-motion seismology used to be that there were fundamental differences between the source characteristics of crustal earthquakes in Japan and in the United States. Joint efforts under this program have shown that this is not so ? the source characteristics belong to the same population. This discovery has more than doubled the data available to the U.S. researchers and benefited greatly the understanding of the earthquake process and the prediction of strong-ground motions in the United States. Joint use of U.S. and Japanese (K-net and Kik-net) data has led to significant improvements in the methods used to predict strong ground motions. These methods were tested successfully in recent earthquakes in Japan and the United States.
  
• Quadrupling of the size of geotechnical engineering databases available to both the Japanese and U.S. research communities.
  
• Extension of the useful life of Magneto-Rheological (MR) fluids from six months to over ten years.
  
• Development of an inexpensive and versatile wireless sensor for crack detection in steel structures.
  
• Development of low-cost, low-power strain memory sensors for detecting damage in critical regions of structures.
  
• A better understanding of the demands and capacities of steel structures was achieved by studying problems that arose in steel moment frame structures during the Kobe and Northridge earthquakes.
  
• Development of a broader societal perspective of performance-based design and acceptable levels of performance for structures and systems in Japan and in the United States.
  
• Development of comparative analyses of U.S. and Japanese earthquake disasters as social phenomena.

The quality of the technical achievements under the Urban Earthquake initiative has been excellent and beyond expectations. This joint U.S.-Japan effort has been extremely successful in terms of interdisciplinary research being carried out on a well-coordinated basis through bilateral collaborations involving engineers and social scientists, exchange of research data and information, development of enabling technologies, and implementation of superior educational activities through extensive exchange of students. The cooperation between researchers in the United States and Japan has been synergistic and has provided intellectual challenges to both sides toward mitigation of the impact of earthquakes on large population centers. The U.S. research community has benefited through this collaboration in many aspects, including the use of facilities not available anywhere else in the world, the pooling of the world’s best research talents in the field from both countries, and the willingness of the Japanese collaborators to implement state-of-the-art research technology into their infrastructures.

A few nuggets are given to highlight some of the research innovations achieved:

1. Built-in Active Diagnostic System Using Network of Piezoelectric Sensors

Professor Fu-Kuo Chang at Stanford University (9812574) with his students Fannie Wu and Hian-Leng Chan developed a smart rebar system which can self-detect bond deterioration and yielding when the rebar is embedded in concrete. The system consists of three major components: a smart rebar with a built-in piezoelectric sensor network, an intelligent diagnostic algorithm and a portable computer. During a routine inspection or after a major earthquake, a crewman can simply connect the portable computer to the smart rebar. The system will automatically detect and monitor the gradual or sudden reduction in bond resistance between steel and concrete and rebar yielding inside concrete. 　In key structural parts such as anchorage areas, beam-column joints and footing areas, bond losses eventually lead to substantial reduction in bond strength, large slippage and increased deformation. 　By placing smart rebars in these critical areas, slippage as a result of damage to the steel-concrete bond interface could be easily detected and monitored. It is believed that active sensing could also be used for slip measurements in both lab and field environments. 　

2. Wireless Sensors for Detection of Welded Steel Cracks

Professors Sharon Wood and Dean Neikirk at the University of Texas at Austin (0000027) have developed a prototype wireless sensor to detect the formation of cracks in welded steel construction. It is envisioned that this inexpensive and reliable sensor would be installed during construction of a building and could be interrogated after an earthquake without removing the fireproofing materials or disrupting the occupants of the building. The prototype sensor comprises two parts: a RF transmitter and a frangible switch. The transmitter is basically an LC circuit, and the switch, which opens when a crack forms in the weld beneath the sensor, includes an added capacitor. Therefore, the state of the switch controls the total capacitance of the sensor. When interrogated using a frequency sweep, the sensor will respond at one frequency when the switch is open and at another frequency when the switch is closed, thereby providing binary information about the state of the structure.

Professor Billie F. Spencer's pioneering efforts in the development of magneto-rheological (MR) fluid dampers for protection of civil engineering structures have led to commercial availability of large-scale MR dampers for civil engineering applications, and the world's first full-scale implementation of these smart dampers in civil engineering structures.　 The first full-scale implementation of MR dampers was seen in the Nihon-Kagaku-Miraikan Building, an exhibition hall in the Tokyo Bay area designed by the Nikken Sekkei Corporation for futuristic science and technology. Two 30-ton MR Fluid dampers built by the Sanwa Tekki Corporation using Lord fluid are installed between 3^rd and 5^th (see left image below). In China, the first full-scale smart damping control of cable stays will be implemented on the Dongting Lake Bridge, located in Yueyang City, Hunan Province, China (see right image below). This project constitutes the world's first full-scale implementation of smart damping strategies for mitigation of stay-cable vibration on long-span bridges, and the world's first full-scale implementation of magneto-rheological dampers for bridge structures.　 Professor Spencer's U.S.-Japan collaborations were essential in facilitating these achievements. 　

4. Performance-Based Engineering Against Near-field Ground Motions

Professor Wilfred Iwan of Caltech (9812522) has developed a new and significantly improved methodology for use in Performance Based Engineering analysis of structures subjected to strong earthquake loading. The new methodology is based on a rigorous statistical analysis of the response of inelastic structures to recently observed near-field ground motions of the type recorded in the Northridge, Kobe, and Chi-Chi earthquakes as well as more traditional far-field ground motions. The method has been cast in the form of a variation of the Capacity Spectrum Method, which is currently used by many structural engineers. This makes the new methodology readily adoptable for practice. The new methodology will be implemented in the next generation of design and analysis procedures being prepared by the Applied Technology Council for the Federal Emergency Management Agency.

University of Missouri-Rolla Civil and Electrical Engineering Professors Genda Chen, James Drewniak, and David Pommerenke (0200381) are developing new Electrical Time Domain Reflectometry (ETDR) coaxial cable sensing techniques for civil infrastructural application. The coaxial cables being developed are distributed sensors that use novel geometries and changes in the outer conductor resulting from small mechanical deformations to identify movement and cracks in civil structures. The concepts will be extended to other cable sensors of different configurations such as co-planar structures for easy installation on the surface of structural members. Existing ETDR techniques are being advanced for accurate measurements of a wide range of strain or crack width in structural engineering applications (left). The location and magnitude of strains/cracks are identified from the direct measurement of the reflection coefficient of electromagnetic waves propagating through a cable. The sensitivity of the newly designed cable sensors is increased from current technologies by more than 10~50 times. As continuous sensors, TDR cables are high in spatial resolution. They are flexible, rugged, and very reliable in large-scale civil infrastructure applications (right).

Professor James Wight of University Michigan (9812464) found in his experimental studies of beam-to-column connections of RC frames (see pictures below) that the joint behavior significantly changes with the spandrel beam eccentricity, and floor slab and the normal beam add considerable torsional stiffness to the subassembly and delay the deterioration of joint shear stiffness and strength. Anchorage conditions for the spandrel beam reinforcement did not significantly deteriorate during the tests.

Analytical studies to evaluate seismic response of reinforced concrete frame structures, with and without joint deformations, demonstrated that the predicted inelastic behavior was not accurate when the joint region is assumed to be rigid. It was observed that some inelastic frame analysis programs have limitations that make them impractical to use, including the lack of output for inelastic rotations in member plastic hinging regions that are necessary to check performance limits.

To plant the seeds for future bilateral U.S.-Japan cooperation, young researcher exchange programs have been developed by both the U.S. and the Japanese sides. From the Japanese side, approximately six young researchers per year were sent to the United States to conduct research. For the U.S. side, the Natural Hazard Mitigation in Japan (NHMJ) program led by Professors B.F. Spencer, Jr. and Y.C. Kurama sends approximately 12 researchers each year to Japan to participate in an intense program of visits to laboratory, university and construction sites (see figure below) to enhance their understanding of Japanese engineering practice. Following this program, the students spend 2 months in Japanese research laboratories under the Summer Institute in Japan, sponsored jointly by the U.S. and Japanese Governments. For more information, see: http://www.nd.edu/~quake/nhmj/.

Future U.S.-Japan Collaboration To Mitigate The Effects of Earthquakes

During an October 2002 JTCC meeting in Kyoto, (which Dr. Esin Gulari, Acting Assistant Director of Engineering at NSF, participated in), the following three main thrusts were selected for future collaboration after a thorough review of Urban Earthquake research accomplishments and technological needs:

These three major thrust areas offer strategic directions for joint U.S.-Japan research that are relevant to control and mitigation of earthquake and other hazards, and are critical for development of a cross-cutting knowledge base and broad-based enabling technologies for critical infrastructures. NSF’s Civil and Mechanical Systems Program will focus on these areas in its development of future joint research efforts with Japan to facilitate rapid advancement of common interests.

U.S.-Japan cooperative research on earthquake engineering and hazard mitigation has come a long way and has made many major contributions. There are many reasons for this history of success, including: (1) merger of two intellectually talented workforces in the field based on common interests and benefiting from complementary strengths and resources, (2) the strong relationships built between the U.S. and Japanese research communities during 25+ years of continuous research cooperation with mutual respect and support, (3) a well-established and highly effective coordination mechanism as implemented over the years through JTCC (for technical issues) and the NSF Tokyo Office (for administrative and logistic issues), and (4) an effective student exchange package, including the Summer Institute in Japan program for U.S. Graduate Students and Research Experience for Undergraduates programs that have been implemented to cultivate the future generation of researchers for cooperative research.

However, changes in scientific and engineering emphases, as well as program administration and management, are expected for the future. Considerations include:

1) Research areas in the future will not be restricted only to the narrow domain of earthquake engineering, which in the past emphasized studies to improve the basic understanding of structural behaviors under earthquakes and to develop improved design methods through traditional engineering approaches. Instead, considerable expansion in the future will occur, including:

--Multiple hazards mitigation solutions

--Integrated approaches for mitigation, rebuild, and recovery

--Sensor-based technologies for infrastructure applications such as health

monitoring for structural safety and security, and eventually smart structures

2) Because the subject areas in sensors and smart structural technologies touch on the interests of many government agencies in Japan (Ministry of Education, Sports Culture, Science and Technology, Ministry of Land, Infrastructure and Transport, and Ministry of Economy Trade and Industry), NSF will strive to develop partnerships to effectively support cooperative research in these important areas. It is crucial to begin pursuing new mechanisms now that would enable multiple agency sponsorship and participation in Japan.

3) NSF desires to explore appropriate mechanisms for proposal submission, review, and funding of cooperative projects with future Japanese government partners.

 

 

 

NSF AWARDS UNDER THE U.S.-JAPAN COOPERATIVE RESEARCH
IN URBAN EARTHQUAKE DISASTER MITIGATION PROGRAM

Back to top

Return to Tokyo homepage