Ambient vibration data analysis for structural identification and global condition assessment

    Authors

    M. Gul;F. N. Catbas

    Comments

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    Abbreviated Journal Title

    J. Eng. Mech.-ASCE

    Keywords

    structural dynamics; vibration; impact tests; modal analysis; damage; assessment; flexibility; EIGENSYSTEM REALIZATION-ALGORITHM; ASCE BENCHMARK PROBLEM; SYSTEM-IDENTIFICATION; MODAL-ANALYSIS; PARAMETER-ESTIMATION; TALL; BUILDINGS; PHASE-I; BRIDGE; Engineering, Mechanical

    Abstract

    System identification is an area which deals with developing mathematical models to characterize the input-output behavior of an unknown system by means of experimental data. Structural health monitoring (SHM) provides the tools and technologies to collect and analyze input and output data to track the structural behavior. One of the most commonly used SHM technologies is dynamic testing. Ambient vibration testing is a practical dynamic testing method especially for large civil structures where input excitation cannot be directly measured. This paper presents a conceptual and reliable methodology for system identification and structural condition assessment using ambient vibration data where input data are not available. The system identification methodology presented in this study is based on the use of complex mode indicator functions (CMIFs) coupled with the random decrement (RD) method to identify the modal parameters from the output only data sets. CMIF is employed for parameter identification from the unscaled multiple-input multiple-output data sets generated using the RD method. For condition assessment, unscaled flexibility and the deflection profiles obtained from the dynamic tests are presented as a conceptual indicator. Laboratory tests on a steel grid and field tests on a long-span bridge were conducted and the dynamic properties identified from these tests are presented. For demonstrating condition assessment, deflected shapes obtained from unscaled flexibility are compared for undamaged and damaged laboratory grid structures. It is shown that structural changes on the steel grid structure are identified by using the unscaled deflected shapes.

    Journal Title

    Journal of Engineering Mechanics-Asce

    Volume

    134

    Issue/Number

    8

    Publication Date

    1-1-2008

    Document Type

    Article

    Language

    English

    First Page

    650

    Last Page

    662

    WOS Identifier

    WOS:000257762600005

    ISSN

    0733-9399

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