Earthquake Damage Detection in Buildings and Early Warning Based on Wave Travel Times

Project supported by NSF, Directorate for Engineering, Division of Civil, Mechanical and Manufacturing Innovation, Grant No. CMMI-0800399; 08/01/08-07/31/11

Principal Investigator: Maria Todorovska; http://www-rcf.usc.edu/~mtodorov/ ; Email: mtodorov@usc.edu

Graduate Student: Mohammadtaghi Rahmani (starting Fall 2009)

University of Southern California, Department of Civil & Environmental Engineering, Los Angeles, CA 90089-2531

Strong Motion Research Group: http://www.usc.edu/dept/civil_eng/Earthquake_eng/

Project Abstract

The objective of this project is to develop a novel methodology for remote structural health monitoring that is robust when applied to actual structures and large amplitude response, and is calibrated using data from full-scale structures. The focus of this project will be on buildings. The methodology is based on detecting changes in travel time of seismic waves propagating through the structure, that have been radiated by a virtual source created by de-convolution of recorded vibration response. The methodology will be calibrated using earthquake records from full-scale buildings that have been damaged or could have been damaged by an earthquake. Further, the effectiveness of this methodology for general condition monitoring will be explored. The major advantages of this wave-based method are that it can localize the damage with relatively small number of sensors, and that it is not sensitive to the effects of soil-structure interaction and changes in other structural boundary conditions.

The availability of a validated methodology that works with real structures and field data will greatly facilitate the decision making during emergency response and recovery following an earthquake, and will help reduce loss of life, injuries and monetary losses caused by earthquakes. For example, a timely decision to evacuate an unsafe building will reduce the risk of loss of life and injuries caused by potential collapse of the weakened structure by its shaking from the aftershocks. The methodology, with capability for general condition monitoring of structures, will be a useful tool in managing the aging infrastructure.

Recent Publications on Structural Health Monitoring

• Earthquake damage detection in buildings and early warning based on wave travel times, Todorovska MI, Proceedings of 2009 NSF Engineering Research and Innovation Conference, Honolulu, Hawaii, June 22-25, 2009, Grant # CMMI-0800399.
• Earthquake damage: detection and early warning in man-made structures, Todorovska MI, Chapter in “Encyclopedia of Complexity and System Science”, R.A. Meyers (Ed.), Section on Complexity in Earthquakes, Tsunamis, and Volcanoes, and Forecasting and Early Warning of their Hazards, W. H. K. Lee (Section Ed.), Springer, in press, pp. 25.

• Seismic interferometry of a soil-structure interaction model with coupled horizontal and rocking response, Todorovska MI , Bull. Seism. Soc. Am., 99(2A), 611-625, 2009.
• Soil-structure system identification of Millikan Library North-South response during four earthquakes (1970-2002): what caused the observed wandering of the system frequencies?, Todorovska MI, Bull. Seism. Soc. Am., 99(2A), 626-635, 2009.

• Environmental effects on measured structural frequencies – model prediction of short-term shift during heavy rainfall and comparison with full-scale observations, Todorovska MI, Al Rjoub Y, Structural Control and Health Monitoring, 16(4), 406-424, 2009.
• Effects of rainfall on soil-structure system frequency: examples based on poroelasticity and a comparison with full-scale measurements, M.I. Todorovska & Y. Al Rjoub, Soil Dynamics and Earthquake Engrg, 26(6-7), 708-717, 2006.  (Special issue on Biot Centennial – Earthquake Engineering).

• Variability of the fixed-base and soil-structure system frequencies of a building – the case of Borik-2 building, Trifunac, MD, M.I. Todorovska, M.I. Manić, and B.Đ. Bulajić, Structural Control and Health Monitoring, DOI: 10.1002/stc.277, in press, 2008.
• Impulse response analysis of the Van Nuys 7-story hotel during 11 earthquakes and earthquake damage detection,  M.I. Todorovska and M.D. Trifunac,  Structural Control and Health Monitoring, 15(1), 90-116, 2008.
• Earthquake damage detection in the Imperial County Services Building I: the data and time-frequency analysis, M.I. Todorovska and M.D. Trifunac, Soil Dynamics & Earthquake Engrg, 27(6), 564–576, 2007.
• Earthquake damage detection in the Imperial County Services Building II: analysis of novelties via wavelets, M.I. Todorovska and M.D. Trifunac, Structural Control and Health Monitoring, in press 2009.
• Earthquake damage detection in the Imperial County Services Building III: analysis of wave travel times via impulse response functions, M.I. Todorovska and M.D. Trifunac, Soil Dynamics & Earthquake Engrg, 28(5), 387–404, 2008.

• Earthquake damage detection in structures and early warning, Todorovska MI, Trifunac MD, Proc. 14^th World Conference on Earthquake Engineering, October 12-17, 2008, Beijing, China, Paper S05-03-010, pp. 10, 2008.

• Identification of fixed-base and rigid body frequencies of vibration of soil-structure systems from recorded response with minimum instrumentation, Todorovska MI , Proc. 14^th World Conference on Earthquake Engineering, October 12-17, 2008, Beijing, China, Paper 11-0173, pp. 10, 2008.
• Threshold changes in building frequencies of vibration associated with structural damage - study of full-scale observations in the Borik-2 building in former Yugoslavia, Trifunac MD, Todorovska MI, Manić MI, Bulajić BĐ, Proc. 14^th World Conference on Earthquake Engineering, October 12-17, 2008, Beijing, China, Paper S05-03-015, pp. 10, 2008.
• Soil-structure interaction and Biot’s theory of wave propagation in poroelastic media as possible explanation for observed changes of apparent frequencies of vibration of a building with heavy rainfall, Todorovska MI, Al Rjoub Y, in Poro-Mechanics IV, Ed. H.I. Ling, A. Smyth and R. Betti, (Proc. of The Fourth Biot Conference on Poromechanics, Columbia University, New York, June 8-10, 2009), pp. 6, 2009.
• Rotational Earthquake Motions - International Working Group and its Activities, Todorovska MI, Igel H, Trifunac MD, Lee WHK, Proc. 14^th World Conference on Earthquake Engineering, October 12-17, 2008, Beijing, China, Paper 03-02-0031, pp. 10, 2008.

• Separation of the effects of soil-structure interaction in frequency estimation of buildings from earthquake records, Todorovska MI, in Coupled site and soil-structure interaction effects with application to seismic risk mitigation, Ed. T. Shanz and Roumen Iankov, Springer, 169-178, 2009.

See also section on Structural Health Monitoring of the research group Selected Publication page.

Archived Seminar Presentations

• Todorovska MI. “Structural models for rational design, structural health monitoring and seismic risk and loss assessment”, Earthquake Hazards Seminar, U.S. Geological Survey, Menlo Park, California, 17 January 2008. [ mms://video.wr.usgs.gov/ehz/2008/20080117.wmv ] http://earthquake.usgs.gov/regional/nca/seminars/?year=2008.

Imperial County Services Building

Imperial County Services Building (6-story RC structure damaged by the 1979 Imperial Valley, California earthquake). Conceptual model (top, left), photos of the damage (top, right), and impulse responses for the EW (longitudinal response for tree time intervals: 0-7 s, 7-13 s and 13-24.5 s. Redrawn from Earthquake damage detection in the Imperial County Services Building III: analysis of wave travel times via impulse response functions, M.I. Todorovska and M.D. Trifunac, Soil Dynamics & Earthquake Engrg, 28(5), 387–404, 2008.

Van Nuys Hotel 7-story, RC, EW (longitudinal response), 11 earthquakes and 5 ambient vibration tests in 24 years fsys – system frequency computed form time-freq. energy distribution, f1 – fixed-base frequency computed from wave travel times.
Fixed base frequency (f_1, obtained from wave travel time analysis) and system frequency (f_sys, obtained from time-frequency analysis) of the Van Nuys 7-story hotel during 11 earthquakes. Redrawn from: Impulse response analysis of the Van Nuys 7-story hotel during 11 earthquakes and earthquake damage detection,  M.I. Todorovska and M.D. Trifunac,  Structural Control and Health Monitoring, 15(1), 90-116, 2008.