System Identification for Structural Health Monitoring

System identification (SI) techniques play an important role in investigating and reducing gaps between the constructed structural systems and their structural design models, and in structural health monitoring for damage detection. A great amount of research has been conducted in SI. Modal-parameter SI and physical-parameter SI are two major branches in SI. The former is appropriate for identifying the overall mechanical properties of a structural system and exhibits stable characteristics in implementation. While the latter is important from different viewpoints, e.g. enhancement of reliability in active controlled structures or base-isolated structures, and its development is limited due to the requirement of multiple measurements or the necessity for complicated manipulation. A mixed approach is often used in which physical parameters are identified from the modal parameters obtained by the modal-parameter SI. However, a sufficient number of modal parameters must be obtained for the unique and accurate identification of the physical parameters. This requirement is usually hard to satisfy.In spite of the importance of damping in the seismic-resistant design of buildings, it does not appear that identification techniques have been developed sufficiently. Furthermore, it is believed in general that the acceleration records in all the floors above a specific story are necessary to evaluate the story shear force, which is required in the stiffness - damping evaluation. This instrumentation may be unrealistic in multi-storied buildings. To overcome this difficulty, a unique system identification theory is explained for a shear building model. It is shown that unique identification of story stiffness and viscous damping coefficients is possible when acceleration records at the floors just above and below a specific story are available. This book is the first text book on smart techniques of mechanical system identification using records from limited locations. The techniques explained in this book are based upon rich content published in international journal papers by the authors and includes an introductory explanation for a broad class of readers.

Table of Contents:
Contents Chapter 1 Introduction; Background and Review; Fundamentals of Dynamics; Frequency independent and frequency-dependent stiffness; Viscous damping and linear hysteretic damping; Vibration under external force; Vibration under base acceleration; Time series analysis; Conventional Techniques for System Identification; Organization of this Book; References Chapter 2 Stiffness-damping Simultaneous Identification Using Limited Earthquake Records Introduction; Stiffness-damping Simultaneous Identification: Theory; Identification system; Identification of stiffness and linear hysteretic (material) damping; Identification of viscous damping; Verification of Theory Through Numerical Simulation Models; Numerical simulation model; Identification of stiffness; Identification of linear hysteretic damping; Identification of viscous damping; Verification of Theory Through Actual Limited Earthquake Records; Earthquake records in a base-isolated building; Identification of stiffness; Identification of damping; Identification of Maxwell-type Models; Summaries; References Chapter 3 System Identification Using One-dimensional Shear Beam Finite-element Models and Limited Earthquake Records Introduction; One-dimensional Shear Beam Subjected to Horizontal Earthquake Ground Motion; Case of viscous damping; Case of linear hysteretic damping; Relation of Fourier Transformed Recorded Ground Motion with Model Properties; Identification of Stiffness and Linear Hysteretic (Material) Damping; Identification by Use of Recorded Ground Motion Data; Identification based on records just below engineering bedrock; Identification based on dense records; Summaries; References Chapter 4 Temporal Variation of Modal Properties of a Base-isolated Building During an Earthquake Introduction; System Identification Method; Observation of Earthquake Records in Base-isolated Building; Result of Modal-parameter System Identification; Summaries; References Chapter 5 Stiffness-damping Simultaneous Identification Under Limited Observation with Noise: Preliminary Approach Introduction; Stiffness-damping Simultaneous Identification: Theory; Identification system; Identification of stiffness and linear hysteretic damping; Identification of viscous damping; Extension to Stationary Random Vibration; Noise Elimination and Reduction; Noise elimination and reduction (1); Noise elimination and reduction (2); Verification of Theory Through Numerical Simulation Models; Numerical simulation model; Identification of stiffness; Identification of linear hysteretic damping ratio and viscous damping coefficient; Verification of Theory Through Actual Limited Records; Actual record in base-isolated building as approximate stationary random process; Identification of stiffness; Identification of damping; Validity of Limit Manipulation at Zero Frequency; Summaries; References Chapter 6 Noise Effect in Physical-parameter System Identification Under Stationary Random Input Introduction; Stiffness-damping Simultaneous Identification; Identification of stiffness and linear hysteretic (material) damping; Application of smart identification technique to stationary random vibration; Effect of Noise Level and Correlation on Identification; Formulation under noisy environment; Modeling of noise considering correlation between noises; Theoretical analysis of effect of noise level and correlation on identification; Numerical simulation method in frequency domain; Numerical examination; Summaries; References Chapter 7 Noise-bias Compensation Method (I)for Small-amplitude Stationary Random Input Introduction; Stiffness-damping Simultaneous Identification Under Stationary Input; Noise-bias Compensation Method (I) Based on Prediction of Noise Levels and their Coherency; Modeling of noise considering correlation between noises; Prediction of noise levels and their coherency; Noise-bias compensation method; Numerical example (2-story model); Numerical example (5-story model); Summaries; References Chapter 8 Noise-bias Compensation Method (II) for Small-amplitude Stationary Random Input Introduction; Stiffness-damping Simultaneous Identification Under Stationary Input; Effect of Noise on Identification; Formulation under noisy environment; Numerical examination; Noise-bias Elimination Method (II) based on; Prediction of Noise Levels without Limit Manipulation; Method for estimation of the level of noises and compensation of the effect of noises without limit manipulation; Numerical example using the proposed noise-bias compensation method; Example using actual microtremor records; Summaries; References Chapter 9 Stiffness-damping Simultaneous Identification of Buildings Including Unknown Inner Vibration Source Introduction; Stiffness-damping Identification Under Unknown Input; Stiffness-damping identification using response under ground-motion input; Stiffness-damping identification using response under unknown inner vibration source; System Identification Including Unknown Inner Vibration Source; Overview of the proposed method; System identification in case of unknown stiffnesses and damping coefficients; Physical interpretation of system identification using limit at zero frequency; Numerical Examples; Prediction of fundamental natural frequency and the lowest-mode damping ratio; Prediction of position of inner load; Stiffnesses and damping coefficients at upper stories; Stiffness ratios in the lower stories; Stiffness level in the lower stories; Damping coefficient ratios in the lower stories; Damping coefficient level in the lower stories; Application to Test Structures; Improved Identification Method based on ARX Model; Modeling of transfer function; Outline of new noise compensation method; High-pass filtering; Optimal cutting frequency; Numerical example using improved identification method; Summaries; References Chapter 10 Stiffness-damping Simultaneous Identification Based on Extrapolation of Unrecorded Response to Ground Motion Introduction; Identification Method Using Limit Manipulation; Identification of stiffness and damping coefficient; Uniqueness of identification of structural parameters including unrecorded story; Identification Method Based on Extrapolation of Unrecorded Data (Method 1); Extrapolation of unrecorded data; Identification method using extrapolated data; Numerical examples; Identification Method Based on Direct Estimation of Physical Parameters (Method 2); Identification method without limit manipulation; Numerical examples; Summaries; References Chapter 11 Stiffness-damping Identification of Buildings Using Limited Earthquake Records and ARX Model Introduction; Identification of Stiffness and Damping Coefficient Using Limit Manipulation; Identification of Stiffness and Damping Coefficient Using ARX Model; Summary of procedure; Taylor series expansion of transfer function; Relation of the limit value of transfer function with ARX parameters; ARX parameter expression of identification function; ARX parameter estimation with constraints; Numerical Examples; Numerical simulation model; Transfer function in terms of ARX parameters; Order of ARX model; Identification of stiffness; Identification of damping; Application of the Method to Actual Recorded Data for Miniature Model Structures; One-story model; Four-story model; Application of the Method to Actual Base-isolated Building; Summary; Appendix 1 ARX Model (Adachi 2009); Appendix 2 ARX Parameter Expression of Transfer Function; Appendix 3 Prediction Error in ARX Model; Appendix 4 Least-mean-square Estimate of Parameter Vector; References Concluding Remarks: Future Directions Introduction; Identification of Hysteretic Restoring-force Characteristics; Identification Under Noisy Environment (Low S/N Ratio); Identification Under Small-level Vibration; Validation of Theories Using Actual Recorded Data; New Measurement System; Summary; References

About the Author :
Izuru Takewaki (Doctor of Engineering, Kyoto University) is Professor of Building Geoenvironment Engineering in the Department of Architecture and Architectural Engineering and Associate Dean of the Graduate School of Engineering at Kyoto University, Kyoto, Japan. His research interests include inverse problem in vibration, structural optimization, soil-structure interaction, seismic resistant design of building structures, random vibration theory, critical excitation method, structural reliability, structural dynamics; systematization of structural design process, system identification & health monitoring, construction of design earthquake, surface ground analysis, robust structural design, seismic retrofitting of school buildings, structural control, passive control. He is a member of the Architectural Institute of Japan, Japan Society for Earthquake Engineering Promotion, Japan Association for Earthquake Engineering, American Society of Civil Engineers, Earthquake Engineering Research Institute, American Academy of Mechanics, International Society for Structural and Multidisciplinary Optimization (ISSMO), and the International Society for Computational Engineering & Sciences (ISCES). He served twice as a visiting professor at the University of California, has served as a reviewer for a number of international journals, and has written numerous papers, book chapters, and books in his areas of research, in English as well as in Japanese. Mitsuru Nakamura is Chief Structural Engineer at the Technical Research Institute of Obayashi Corporation. Shinta Yoshitomi is a research associate in Building Geoenvironment Engineering in the Department of Architecture and Architectural Engineering of the Graduate School of Engineering at Kyoto University, Kyoto, Japan. His research interests include Structural Optimization under Constraints to Ensure Practical Design, System Identification and Health Monitoring, Seismic Retrofitting of Wooden House Using Dampers, and Structural Design Support by Using Statistic and Optimization Method. He is the co-author of numerous conference papers in his field.