SUMMARY, RESOLUTIONS AND RECOMMENDATIONS OF
THE THIRD JOINT TECHNICAL COORDINATING
-U.S.-JAPAN COOPERATIVE RESEARCH PROGRAM ON
SMART STRUCTURAL SYSTEMS (AUTOADAPTIVE MEDIA)-
The Third Joint Technical Coordinating Committee (JTCC) Meeting of the U.S.-Japan Cooperative Research Program on Smart Structural Systems (Autoadaptive Media Applied to Civil Infrastructures) was held at the Building Research Institute (BRI) in Tsukuba, Ibaraki, Japan on October 19, 2002. Fifteen U.S. and ten Japanese JTCC members, plus 22 observers participated in the meeting.
The Program is conducted by the U.S. National Science Foundation and BRI, Japan under the aegis of the U.S.-Japan Panel on Wind and Seismic Effects of the U.S.-Japan Cooperative Program on Natural Resources Development Program (UJNR).
Prior to the third JTCC meeting, Workshop on Smart Structural Systems was held at the Building Research Institute for U.S.-Japan Cooperative Research Programs on Smart Structural Systems (Auto-adaptive Media) and Urban Seismic Disaster Mitigation. Individual research findings were reported in the workshop.
In the first part of the JTCC meeting, participants were separated into three groups corresponding to three research thrusts: (1) structural systems, (2) sensing and monitoring technology, and (3) effector technology. Research items, plans and results in detail were discussed on the basis of presentations during the workshop.
In the second part of the JTCC meeting, a plenary session was held. Each working group reported the summary of group discussion and the progress of research. The series of large scale proof-of-concept experiments carried out by the Japanese side were discussed in detail.
The current U.S.-Japan Cooperative Research Program on Smart Structural Systems (Autoadaptive Media Applied to Civil Infrastructures) will end at the end of March, 2003, in Japan and summer, 2003, in the United States. In the concluding session, desired research topics for future cooperation were discussed. The following Resolutions and Recommendations were adopted.
The three main thrusts of the research program on Autoadaptive Media are common for the activities in Japan and in the U.S.A. It was noted, however, that the activities in Japan have a primary emphasis on system applications and proof-of-concept demonstrations while the activities in the US focus on enabling concepts and fundamental aspects of the technological elements.
(1) The meeting was successful and fruitful for both countries and took place in a cordial atmosphere. The participants are pleased to acknowledge the excellent performance of the BRI staff in preparing for and supporting the meeting.
(2) The reports of the working groups were accepted and their superb progress and accomplishment to date were acknowledged.
(3) The series of large scale proof-of-concept experiments in Tsukuba, Japan were critical for the proper development of autoadaptive media for earthquake resistance of buildings.
(4) The bilateral cooperative research work including short/long-term personnel exchange was successfully completed in the large-scale tests conducted in Japan.
(5) The next JTCC meeting should be held in the US before April 2004.
(1) A structured means to facilitate and organize collaborative work and create synergies between the US and Japan should be formalized, e.g., joint funding mechanisms.
(2) The further discussion is needed for future research needs. The following items were identified as possible subjects in the meeting;
1. Dense instrumentation in infrastructure
2. Cooperation between US and Japan on the basis of US NEES (George E. Brown, Jr. Network for Earthquake Engineering Simulation) initiative and the use of E-defense shaking table in Japan.
3. Soil/foundation/structure interaction experiments, especially the comparative study of test results of large-scale shaking table, small-shaking table, and centrifuge tests with field tests.
SUMMARY OF GROUP SESSIONS
Participants of structural systems
Chairpersons: A. WADA Tokyo Institute of Technology
M.A. SOZEN Purdue University
Recorder: R.J. FROSCH Purdue University
Members: A. K. AGRAWAL City College of City University of New York
S. AIZAWA Takenaka Co.
T. AZUHATA BRI
M. EBERHARD University of Washington
H. HIRAISHI Meiji University
I. M. IDRISS University of California, Davis
J.O. JIRSA University of Texas, Austin
T. KABAYASAWA University of Tokyo
H. KURAMOTO Toyohashi University of Technology
E. LOZINCA BRI (Romania)
M. MIDORIKAWA BRI
J. PENZIEN ICE Consultants
K. SHIBA Shimizu Corp.
Y. TAKAHASHI BRI
K. YOSHIMATSU Kumagaigumi Corp.
A number of promising and novel applications for smart structural systems were discussed. These included autoadaptive structural systems with active or semi-active dampers and rocking systems, reinforced concrete structural systems with passive dampers and damage fuses, and innovative systems for life safety. Areas for current research activities are summarized below.
(1) Two shaking table tests of multi-story steel frames provide opportunities to test autoadaptive systems in large scale. A five-story frame was tested at BRI in 2001 to investigate rocking systems. A three-story steel frame was tested in Tsukuba in 2002 with six different autoadaptive systems: rocking systems, seismic-isolation systems with semi-active MR dampers, response control systems with semi-active MR dampers, and damage control systems with fuse elements (cementitious composites). New sensor technologies and damage detection were tested as part of these large-scale, shaking table tests.
(2) Performance-based design and assessment methods are being developed for reinforced concrete structures with damage fuses. Selection of appropriate devices is underway. Practical methods and theoretical formulas for evaluating responses of systems with various dampers are being investigated.
(3) Engineers throughout Japan were surveyed to develop proposals for innovative life safety systems for traditional light construction. Analytical and experimental investigations were carried out for parallel linking of clusters of buildings. Shaking table tests of the parallel linking system were conducted during the summer of 2001.
(4) Eight theme structures (two structural steel and six reinforced concrete) were selected for verifying smart structural systems. Analytical investigations are being conducted with these structures to compare the response of standard frames, structures with base isolation and/or structural control, and rocking systems.
Future collaboration between researchers in the US and Japan is encouraged in two areas:
(1) The large-scale shaking table tests of the three-story steel frame during the spring and summer of 2002 provided a unique opportunity to test different autoadaptive systems, monitoring systems, and effectors. US researchers are encouraged to take advantage of the results from these tests.
(2) Collaborative research is necessary to facilitate the development of design provisions so that smart structural systems can be used efficiently by practicing engineers. Incorporation of smart structural systems into the building inventory has the potential for reducing life-cycle costs, improving the structural performance after extreme events, extending the expected building life, and expanding structural configurations, such as extremely long spans or very tall, slender buildings, where traditional construction may not be possible. Reliable analytical techniques, verified using large-scale laboratory tests of complete structural systems, are needed to accomplish this goal.
II. Sensing and Monitoring Technology
Chairpersons: Y. Kitagawa and Sharon L. WOOD
United States of America side
W.D. IWAN Cal. Tech
Genda CHEN University of Missouri-Rolla
A.M.SERECI Digitexx Data Systems, Inc. Pasadena
Ming L.WANG University of Illinois, Chicago
Sharon L. WOOD University of Texas, Austin
Dean P. NEIKIRK University of Texas, Austin
Hian-Leng Chan Stanford University
S.C. Liu NSF
Yoshikazu KITAGAWA Keio University
Akira MITA Keio University
Takuji HAMAMOTO Musashi Institute of Technology
Shoichi NAKAI Chiba University
Masaomi TESHIGAWARA Building Research Institute
Takashi KAMINOSONO National Institute for Land and Infrastructure Management
Hiroshi ISODA Building Research Institute
Koichi MORITA National Institute for Land and Infrastructure Management
Kazuya NOGUCHI National Institute for Land and Infrastructure Management
Shunsuke Otani University of Tokyo
The purpose of Sensing and Monitoring Technology is to identify research needs for developing new sensing systems, which consist of advanced sensors and infrastructure for data collection, management, and interpretation. Research is needed to develop new types of sensors and obtain information about the long-term robustness of the sensors and data collection infrastructure. The sensors and data collection infrastructure are important parts of smart structural systems in buildings, which include sensors, effectors, and processors.
Highly reliable monitoring systems that combine various advanced sensor systems with system identification, performance assessment, and damage diagnosis and prognosis techniques are required. The monitoring systems must be able to determine the extent and location of damage for different types of structural systems. The information should be made available in a form suitable for use by decision makers immediately after an extreme event, as well as for pre-event and post-event assessment.
Researchers from Japan and the US made presentations about ongoing and planned research. Specific topics are listed below.
A. Sensor Technology
(US) Coaxial Cables as Continuous Sensors for Health Monitoring of Civil Infrastructures
(US) Magnetoelastic Corrosion Sensing of Steel Cables
(US) Development of Wireless Sensors to Detect Cracks in Welded Steel Construction
(US) Bond Characterization Using Active Sensing Diagnostics
(JP) Summary of activities of the Smart sensors working group (including RFID tag, wave, temperature, and wire-saving sensors)
B. Monitoring and Damage Assessment
(JP) Damage Detection Test Using Large Scale Test Frame
(JP) Story Damage Detection of Multistory Buildings Using Natural Frequency Shifts of Multiple Modes
(JP) Time-varying Modal Identification of Damaged Structures by Monte Carlo Filter/Smoother
(JP) Development of Health Monitoring System for an Existing Building
(US) Structural Performance Evaluation Using Real-time Measurement of Hysteretic Behavior
(JP) Development of Real-time Residual Seismic Capacity Evaluation System
(JP) Damage Detection Using Support Vector Machine on Modal Frequency Patterns for a Building Structure
(JP) Recent Progress in Structural Health Monitoring of NEDO Smart Material/Structure Program
C. Development of Sensor Networks
(US) Structural Health Monitoring –A New Paradigm
(JP) Development of Sensor Network with RT-Linux
The Japan and US sides recognize the importance of cooperative research that encourages progress in sensor technology, monitoring and damage assessment, and networking. Exchange of existing data is critical for future progress.
A summary report of the sensor and monitoring component the five-year US-Japan cooperative program on smart structural systems should be published before the next JTCC meeting.
A data repository should be established to calibrate and validate damage detection models.
One or more demonstration projects should be developed to evaluate new sensor technologies and sensor networks.
To assure and enhance cooperative effort in this joint research program, exchange of researchers involved in both countries is essential.
III. Effector technology
Chairpersons: T. Fujita University of Tokyo
B. F. Spencer, Jr. University of Illinois at
Record: H. P. Gavin Duke University
M. Iiba BRI
Members: S. Soda Waseda University
H. Fujitani BRI
N. Inoue BRI
H. Suwada NILIM
T. Hiwatashi BRI
L. H. Weber NSF
H. Matamoros Univ. of Kansas
G. Fischer Univ. of Hawaii
9:05-9:25 Presentation of Japanese activities
(SMA, MR, Strain induced material and Cementitious composites)
9:25-9:40 Presentation of US activities
9:40-10:30 Discussion of collaboration works and contents of summary of the effector technology.
The purpose of the effector technology research group is to develop smart materials and smart devices and to verify that they can effectively control the response of structures. Characteristics of smart materials and devices will be investigated and reported. By relating their characteristics to the applications, methods of implementing this technology will be evaluated (e.g. suitable placement, required capacity, effective use, etc).
Through cooperative research in effector technologies in the US and Japan, the exchange of knowledge and results is expected to be significant and very useful to both countries in advancing this important technology.
(1) Various smart materials, such as shape memory alloys (SMA), magneto-rheological (MR) fluids, piezoelectric and magnetostrictive elements, and high performance fiber reinforced cementitious composites (HPFRCC) have been selected as having high potential.
(2) Research progress and results achieved in 2000 to 2002 were reported. Presentations on effector technology demonstrated that significant progress has been made. Members of the research group are encouraged by these achievements and by the potential for this technology to increase structural performance and mitigate natural disasters.
(3) Research to-date has achieved the following:
a) Properties of SMA (Ni-Ti alloy) bars were investigated. For application of SMA to structural usage, the experiments on main bars of mortar beam, bolted connection of steel beam-column joints, and bridge restrainers were carried out.
b) MR fluids with improved stability were developed and applied to MR dampers for practical application. The validity of various control methods for MR dampers were verified by conducting small and large-scale shake-table tests for smart base-isolation and for story drift control.
c) A field test of a PVDF sensor was carried out, pointing out problems to be solved in future work. A fundamental study was made for semi-active seismic isolation system using piezoelectric actuators.
d) US-Japan collaborative work has been carried out on material and structural tests. Practical applications of several types of HPFRCC are being investigated. Composite material performance has been successfully translated into performance enhancement of structural components and sub-systems. Effectiveness of HPFRCC for damage control and auto-adaptive structural response control has been demonstrated.
e) Large scale shaking table tests on controllable base-isolation and story-drift control systems, using MR dampers and controllable oil dampers, were carried out in 2002 through collaborative efforts between the Japan-side (BRI-NIED) and the US-side (Duke Univ.)
(1) Members of the effector technology research group will continue to aggressively carry out research on this technology focused toward materials, devices, and structural systems that are adaptive in order to demonstrate the effectiveness of this technology for maintaining the functionality and increasing the safety of structural systems, and disaster recovery. This technology will enable engineers to control damage in structural systems and improve constructability.
(2) Research effort should concentrate on the following adaptive materials and devices:
a) Shape memory alloys
b) Controllable fluids (e.g. magneto-rheological fluids)
c) Induced Strain Actuators
d) High-performance fiber reinforced cementitious composites (HPFRCC)
(3) Final Results and Future research plans for the current project are as follows:
a) SMA devices for residential construction will be improved and tested by using the pseudo-dynamic test method.
b) The durability of the magneto-rheological fluid as well as the damper should be verified for the application to real buildings.
c) Semi-active seismic isolation system using piezoelectric actuators will be studied in more detail by simulation analysis.
d) Construction methods of HPFRCC components and systems will be investigated. Research is also continued to examine the use of HPFRCC devices in a smart structural system.
(4) It is recommended that future work continue in the assessment of the applicability and efficacy of smart materials. Specifically:
a) Large-scale prototype and components for autoadaptive devices and smart material components should be developed and evaluated.
b) Evaluation should entail large scale testing of devices on shaking table systems and with pseudo-dynamic methods.
c) The results of testing should be used to determine the dynamic mechanical properties of autoadaptive devices and smart structural components and of the overall structural performance of complete autoadaptive systems.
(5) Members of the effector technology research group will vigorously exchange information and research results. The research group strongly recommends and encourages the exchange of researchers between the US and Japan.