Considerable research has been conducted at the SSTL at the University of Illinois at Urbana-Champaign and the SDC/EEL at the University of Notre Dame in various aspects of structural control for civil engineering applications. This page contains selected papers that document these efforts.

The support provided by the National Science Foundation under research grants BCS 90-06781, CMS 93-01584 and CMS 95-28083, and under National Science Foundation equipment grants BCS 92-1270 and CMS 95-00301 (Dr. S.C. Liu, Director for the Earthquake Hazard Mitigation Program) is gratefully acknowledged.

Table of Contents

• Current Status of Structural Control Research
• Magnetorheological Dampers
• Structural Health Monitoring and "Smart" Sensors
• Acceleration Feedback Experiments
• Practical Issues in Structural Control
• Analytical Methods
• Videos of Experimental Results
  

Current Status

An overview of the current status of structural control for civil engineering applications is presented in the following papers:

• B. F. Spencer, Jr. and Michael K. Sain, "Controlling Buildings: A New Frontier in Feedback," IEEE Control Systems Magazine: Special Issue on Emerging Technologies (Tariq Samad Guest Ed.), Vol. 17, No. 6, pp. 19-35, 1997.

• B. F. Spencer, Jr. and T. T. Soong, "New Applications and Development of Active, Semi-Active and Hybrid Control Techniques for Seismic and Non-Seismic Vibration in the USA," Proceedings of International Post-SMiRT Conference Seminar on Seismic Isolation, Passive Energy Dissipation and Active Control of Vibration of Structures Cheju, Korea, August 23-25, 1999.

• T. T. Soong and B. F. Spencer, Jr., "Supplemental Energy Dissipation: State-of-the-Art and State-of-the-Practice," Engineering Structures, 24(3), pp. 243-259, 2002.
  

Magnetorheological Dampers: A New Means for Semi-Active Control

Much of the current effort in the SDC/EEL is focused on the development of semi-active control strategies. Passive and active control systems represent the two ends of the spectrum in the use of supplemental damping for response reduction in civil engineering structures subjected to strong earthquakes and severe winds. Recently developed semi-active control systems appear to combine the best features of both approaches, offering the reliability of passive devices, yet maintaining the versatility and adaptability of fully active systems. Magnetorheological (MR) dampers are new semi-active control devices that use MR fluids to create controllable dampers. Initial results indicate that these devices are quite promising for civil engineering applications. They are capable of generating large forces, they offer highly reliable operation at a modest cost and can be viewed as fail-safe in that they become passive dampers should the control hardware malfunction. The following papers document our recent research results in this exciting new area.

• G.Yang."Large-Scale Magnetorheological Fluid Damper for Vibration Mitigation: Modeling, Testing and Control," Ph.D dissertation, University of Notre Dame, 2001.

• R.Christenson."Semiactive Control of Civil Structures for Natural Hazard Mitigation: Analytical and Experimental Studies," Ph.D dissertation, University of Notre Dame, 2001.

• E. A. Johnson, G. A. Baker, B. F. Spencer, Jr., and Y. Fujino. "Semiactive Damping of Stay Cables," Engineering Mechanics, 2002, in press.

• E. A. Johnson, R. E. Christenson, and B. F. Spencer, Jr. "Semiactive Damping of Cables with Sag," Computer Aided Civil and Infrastructure Engineering, 2002, in review.

• J. C. Ramallo, E. A. Johnson, and B. F. Spencer, Jr."‘‘Smart’’ Base Isolation Systems," Journal of Engineering Mechanics, ASCE, 128(10), pp. 1088-1099,2002.

• H. Yoshioka, J. C. Ramallo, and B. F. Spencer, Jr. "‘‘Smart’’ Base Isolation Strategies Employing Magnetorheological Dampers," Journal of Engineering Mechanics, ASCE, 128(5), pp. 540-551, 2002.

• G.Yang, B. F. Spencer, Jr., J. D. Carlson, and M. K. Sain."Large-Scale MR Fluid Dampers: Modeling and Dynamic Performance Considerations," Engineering Structures, 24(3), pp.309-323, 2002.

• G.Yang., H. J. Jung, and B. F. Spencer, Jr. "Dynamic Modeling of Full-Scale MR Dampers for Civil Engineering Applications," US-Japan Workshop on Smart Structures for Improved Seismic Performance in Urban Region, Seattle, WA, Aug. 14–16, 2001.

• B. F. Spencer, Jr., S. J. Dyke, M.K. Sain and J. D. Carlson, "Phenomenological Model of a Magnetorheological Damper," Journal of Engineering Mechanics, ASCE, Vol. 123, No. 3, pp. 230-238, 1997.
  
  
• S. J. Dyke, B.F. Spencer, Jr., M.K. Sain and J. D. Carlson, "Modeling and Control of Magnetorheological Dampers for Seismic Response Reduction," Smart Materials and Structures, Vol. 5, pp. 565-575, 1996.
  
  
• S. J. Dyke, B. F. Spencer, Jr., M. K. Sain and J. D. Carlson, "An Experimental Study of MR Dampers for Seismic Protection," Smart Materials and Structures: Special Issue on Large Civil Structures, 1997
  
  
• B.F. Spencer, Jr., G. Yang, JD Carlson, and M.K. Sain, "'Smart' Dampers for Seismic Protection of Structures: A Full-Scale Study," Proceedings of the Second World Conference on Structural Control (2WCSC), Kyoto, Japan, June 28 - July 1, 1998, Vol. 1, pp. 417-426.
  
  
• E. A. Johnson, J. C. Ramallo, B. F. Spencer, Jr., and M. K. Sain, "Intelligent Base Isolation Systems," Proceedings of the Second World Conference on Structural Control (2WCSC), Kyoto, Japan, June 28 - July 1, 1998. , Vol. 1, pp. 367-376.
  
  
• Full-scale 20 tons Seismic Magnetoreological Damper Experiment
  
  
• Also see the Rheonetic homepage: http://www.rheonetic.com/

Structural Health Monitoring and "Smart" Sensors

Recent research efforts have also been directed towards Structural Health Monitoring and "Smart" Sensors, which is emerging as an interesting research area in the field of civil engineering. Papers in this section reflect our studies in this area to date.

• Yong Gao, “Structural Health Monitoring Strategies for Smart Sensor Networks,” Ph.D dissertation, University of Illinois at Urbana-Champaign, 2005.
  
  
• B.F. Spencer Jr., M. Ruiz-Sandoval and N. Kurata, “Smart Sensing Technology: Opportunities and Challenges,” Journal of Structural Control and Health Monitoring, in press, 2004.
  
  
• Y. Gao and B.F. Spencer, "Damage Localization under Ambient Vibration Using Changes in Flexibility," Journal of Earthquake Engineering and Earthquake Vibration, 1(1), pp. 136-144, 2002.
  
  
• Y. Gao, B.F. Spencer, Jr., and D. Bernal, "Experimental Verification of the Damage Locating Vector Method,"Proc. of the 1st International Workshop on Advanced Smart Materials and Smart Structures Technology, Honolulu, Hawaii, January 12-14, 2004
  
  
• T. Nagayama, M. Ruiz-Sandoval, B. F. Spencer Jr., K. A. Mechitov, and G. Agha, "Wireless Strain Sensor Development for Civil Infrastructure," Proceedings of First International Workshop on Networked Sensing Systems, Tokyo, Japan, June 2004; 97-100.
  
  
• Kurata, N., Spencer, B.F. jr. and Ruiz-Sandoval M., "Risk Monitoring by Ubiquitous Sensor Network for Hazard Mitigation," Proceedings of International Symposium on Network and Center-Based Research For Smart Structures Technologies and Earthquake Engineering (SE04) July 6-9, 2004. Osaka University, Osaka, Japan Paper SE04-083
  
  
• N. Kurata, B. F. Spencer Jr., M. Ruiz-Sandoval, Y. Miyamoto and Y. Sako, "A Study on Building Risk Monitoring Using Wireless Sensor Network MICA-Mote," Proceedings of First International Conference on Structural Health Monitoring and Intelligent Infrastructure. Tokyo, Japan November 13-15, 2003
  
  
• M. Ruiz-Sandoval, B.F. Spencer Jr. and N. Kurata, "Development of a High Sensitivity Accelerometer for the Mica Platfor," Proceedings of International Workshop on Advanced Sensors, Structural Health Monitoring, and Smart Structures, November 10-11, 2003, Keio University, Japan

Acceleration Feedback Experiments

Another focus of the research has been the implementation of acceleration feedback control strategies. Various actuator configurations have been studied, including: Active Bracing, Active Mass Driver and Active Tendon Systems. The development of experiments implementing these methods of control and the associated results are summarized in the first paper listed in this section. The subsequent papers discuss in more detail the work done in the implementation of an Active Tendon System at the National Center for Earthquake Engineering Research, Buffalo, New York and an Active Mass Driver system at the SDC/EEL.

• B.F. Spencer, Jr., S.J. Dyke and M.K. Sain, "Experimental Verification of Acceleration Feedback Control Strategies for Seismic Protection," Proceedings of the Japanese Society of Civil Engineers 3rd Colloquium on Vibration Control of Structures, Tokyo, Japan, August 7?, 1995, Part A, pp. 259-265, 1995.
  
  
• S.J. Dyke, B.F. Spencer, Jr., P. Quast, M.K. Sain, D.C. Kaspari, Jr. and T.T. Soong, "Experimental Verification of Acceleration Feedback Control Strategies for an Active Tendon System," National Center for Earthquake Engineering Research Technical Report NCEER?4?024, August 29, 1994.
  
  
• S.J. Dyke, B.F. Spencer, Jr., P. Quast, DC Kaspari, Jr., and M.K. Sain, "Implementation of an Active Mass Driver Using Acceleration Feedback Control," Microcomputers in Civil Engineering: Special Issue on Active and Hybrid Structural Control, Vol. 11, pp. 305-323.
  
  
• M. Battaini, G. Yang, B.F. Spencer, Jr., "Bench-Scale Experiment for Structural Control," Journal of Engineering Mechanics, ASCE, Vol.126, No. 2, pp. 140-148, 2000.
  
  
• R.E. Christen, B.F. Spencer, Jr., N. Hori, K. Seto, "Coupled Building Control Using Acceleration Feedback," Computer-Aided Civil and Infrastructure Engineering, 18(1), pp. 4-18, 2003.

Practical Issues in Structural Control

In addition, the research at the SDC/EEL has furthered the understanding of a number of issues that are important to successful design and implementation of structural control systems. Issues such as Control-Structure Interaction (CSI) and Digital Control Implementation have been investigated and accounted for in the work performed at the SDC/EEL. The following are representative papers in these areas.

• S.J. Dyke, B.F. Spencer, Jr., P. Quast and M.K. Sain, "The Role of Control-Structure Interaction in Protective System Design," Journal of Engineering Mechanics, ASCE, Vol. 121, No. 2, pp. 322?38, 1995.
  
  
• P. Quast, M.K. Sain, B.F. Spencer, Jr. and S.J. Dyke, "Microcomputer Implementations of Digital Control Strategies for Structural Response Reduction," Microcomputers in Civil Engineering: Special Issue on New Directions in Computer Aided Structural System Analysis, Design and Optimization, Vol. 10, pp. 13?5, 1995.

Analytical Methods

A number of efforts have been undertaken to develop methods for control analysis and synthesis specific to civil engineering applications. The papers in this section deal with with concepts in reliability-based robust control and frequency-domain optimal control methods.

• B.F. Spencer, Jr., M.K. Sain, J.C. Kantor and C. Montemagno, "Probabilistic Stability Measures for Controlled Structures Subject to Real Parameter Uncertainties," Smart Materials and Structures, Vol. 1, pp. 294?05, 1992.
  
  
• B.F. Spencer, Jr., M.K. Sain, C.-H. Won, DC Kaspari Jr. and P.M. Sain, "Reliability-Based Measures Of Structural Control Robustness," Structural Safety, Vol. 15, pp. 111?29, 1994.
  
  
• B.F. Spencer, Jr., J. Suhardjo and M.K. Sain, "Frequency Domain Optimal Control Strategies for Aseismic Protection," Journal of Engineering Mechanics, ASCE, Vol. 120, No. 1, pp. 135?59, 1994.

Videos of Experimental Results

The results from Active Bracing and Active Mass Driver (AMD) experiments performed at the SDC/EEL at the University of Notre Dame have been documented in two videos. The videos also show the SDC/EEL facilities and equipment. Two short clips from the video of the active mass driver experiment are available by clicking below. Requests for copies of the complete video may be directed to Prof. B.F. Spencer, Jr. at: bfs@uiuc.edu

Video Clip of AMD Experiment - MPEG, 1.3 MB

This video clip demonstrates the effectiveness of the Active Mass Driver System for Structural Control through use of a split screen display. The top image shows the uncontrolled response, while the bottom image displays the response to the same ground excitation, but this time with control on.

Close-up of the AMD in Action - MPEG, 1.0 MB

This video clip shows a close-up of the AMD operating in the Control On state.

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