This paper deals with the applicability of system realization using the information matrix (SRIM) system identification technique combined with moving time windows (called WSRIM) in order to evaluate the time-varying dynamic properties and damage of a building based on its real earthquake records considering the soil–structure interaction effect. Successive short segments of inputs and their corresponding output signals are selected and structural properties exhibited during that segment of time are identified. Both numerical simulation and real earthquake response measurements from several floors and foundations are utilized to verify the accuracy of the proposed time-varying system identification technique. In addition, the seven-storey reinforced concrete building of the Civil and Environmental Engineering Department at the National Chung Hsing University experienced moderate structural damage during the 1999 Taiwan Chi-Chi earthquake. This paper evaluated the time-varying modal parameters of this building on the basis of records of its acceleration response to the Chi-Chi earthquake main shock and its numerous after-shocks. It is proved that the proposed system identification technique is useful for real-time dynamic property estimation and damage assessment of buildings.

https://iopscience.iop.org/article/10.1088/0964-1726/14/3/017/pdf

On-line building damage assessment based on earthquake records

A procedure has been presented in this paper to identify the structural parameters, viz. mass and stiffness matrices, from modal test data for multistorey shear buildings. The first two orders of modal data have been used by other researchers to estimate the global matrices where they depend only on measurable points which are less than the total number of structural degrees of freedom. The above method has been refined here by using Holzer criteria along with other numerical methods to estimate the global mass and stiffness matrices of the structure. This shows the methodology to be more efficient and accurate. The reliability of the procedure has been shown by examples of multistorey buildings. Copyright © 2004 John Wiley & Sons, Ltd.

Identification of structural parameters of multistorey shear buildings from modal data

http://profdoc.um.ac.ir/articles/a/1059125.pdf

A new iterative model updating technique based on least squares minimal residual method using measured modal data

Estimation of the modal mass of a structure with a tuned-mass damper using H-infinity optimal model reduction

Research highlights? Two novel methods for identification of mass-damping-stiffness of shear buildings. ? In the first method, modal properties are estimated from forced vibration responses. ? In the second method, a direct strategy of structural identification is developed. ? The noise effects may partially be eliminated by using high-order FIR filters. In this research, two novel methods for simultaneous identification of mass-damping-stiffness of shear buildings are proposed. The first method presents a procedure to estimate the natural frequencies, modal damping ratios, and modal shapes of shear buildings from their forced vibration responses. To estimate the coefficient matrices of a state-space model, an auto-regressive exogenous excitation (ARX) model cooperating with a neural network concept is employed. The modal parameters of the structure are then evaluated from the eigenparameters of the coefficient matrix of the model. Finally, modal parameters are used to identify the physical/structural (i.e., mass, damping, and stiffness) matrices of the structure. In the second method, a direct strategy of physical/structural identification is developed from the dynamic responses of the structure without any eigenvalue analysis or optimization processes that are usually necessary in inverse problems. This method modifies the governing equations of motion based on relative responses of consecutive stories such that the new set of equations can be implemented in a cluster of artificial neural networks. The number of neural networks is equal to the number of degree-of-freedom of the structure. It is shown the noise effects may partially be eliminated by using high-order finite impulse response (FIR) filters in both methods. Finally, the feasibility and accuracy of the presented model updating methods are examined through numerical studies on multistory shear buildings using the simulated records with various noise levels. The excellent agreement of the obtained results with those of the finite element models shows the feasibility of the proposed methods.

Model updating of multistory shear buildings for simultaneous identification of mass, stiffness and damping matrices using two different soft-computing methods

A method that estimates mass and stiffness matrices of shear building from modal test data is presented in this paper. The method depends on only measurable points that are less in number than the total structural degrees of freedom, and on the first two orders of structural mode measured. So it is applicable to most of the general test. Based on this method modal data of unmeasurable points are estimated, then global mass and stiffness matrices of structure are obtained by using the first two orders of modal data. Taking advantage of iteration the optimum global mass and stiffness matrices are gained. Finally, an example is studied in this paper. Its result shows that this method is reliable. © 1998 John Wiley & Sons, Ltd.

Zhifeng Wu

Papers

Estimated mass and stiffness matrices of shear building from modal test data