**System Identification in Time Domain**
**for Structural Damage Assessment**
**Using L1-Regularization and Time Windowing Technique**
**Seung Keun Park**
**ABSTRACT**
This paper presents a system identification scheme in time domain to estimate stiffness and damping parameters of a structure using measured acceleration. An error function is defined as the time integral of the least-squared error between measured accelerations and calculated accelerations by a numerical model of a structure. Damping parameters as well as stiffness properties of a structure are considered as system parameters. To alleviate the ill-posedness of SI problems two regularization techniques are employed. *L*_{2}-Regularization function defined by the *L*_{2}-norm of the first derivative of system parameters with respect to time and *L*_{1}-Regularization function defined by the *L*1-norm of the first derivative of system parameters with respect to time are proposed to alleviate the ill-posed characteristics of inverse problems and to accommodate discontinuities of system parameters in time. In *L*_{2}-Regularization scheme, the regularization factor is determined by the geometric mean scheme. In *L*_{1}-Regularization scheme, regularization effect is determined by a truncation number of TSVD(Truncated Singular Value Decomposition). The time window concept is proposed to trace variation of system parameters in time. To represent discontinuity of system parameters in time, *L*_{1}-Regularization scheme is employed in time windowing technique. The validity of the proposed method is demonstrated by a numerical simulation study on a two-span truss bridge.
**Key Word**
Time-domain system identification, Regularization, Time Windowing Technique, Rayleigh damping
[Full Text in Korean (PDF:663K)]
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