Doctoral Dissertations

Hongya Qu

Abstract

"Time-varying structural systems are often encountered in civil engineering. As extreme events occur more frequently and severely in recent years, more structures are loaded beyond their elastic conditions and may thus experience damage in the years to come. Even if structures remain elastic, energy dissipation devices installed on structures often reveal hysteretic behaviors under earthquake loads. Therefore, it is imperative to develop and implement novel technologies that enable the identification and damage detection of time-varying systems. In this dissertation, adaptive wavelet transform (AWT) and multiple analytical mode decomposition (M-AMD) are proposed and applied to identify system properties and detect damage in structures. AWT is an optimized time-frequency representation of dynamic responses for the extraction of features. It is defined as an average of overlapped short-time wavelet transforms with time-varying wavelet parameters in order to extract time-dependent frequencies. The effectiveness of AWT is demonstrated by various analytical signals, acoustic emission and impact echo responses. M-AMD is a response decomposition method for the identification of weakly to moderately nonlinear oscillators based on vibration responses. It can be used to accurately separate the low and high frequency components of time-varying stiffness and damping coefficients in dynamic systems. The efficiency and accuracy of the proposed M-AMD are evaluated with three characteristic nonlinear oscillators and a 1/4-scale 3-story building model with frictional damping under seismic excitations. Finally, AWT-based M-AMD is applied to decompose the measured dynamic responses of a 1/20-scale cable-stayed bridge model tested on four shake tables and evaluate the progression of damage under increasing earthquake loads"--Abstract, page iii.

Advisor(s)

Chen, Genda

Committee Member(s)

Anderson, Neil L. (Neil Lennart), 1954-
ElGawady, Mohamed
Sneed, Lesley
Yan, Guirong Grace

Department(s)

Civil, Architectural and Environmental Engineering

Degree Name

Ph. D. in Civil Engineering

Sponsor(s)

National Science Foundation (U.S.)
Missouri University of Science and Technology

Comments

Financial support to complete this study was provided in part by the U.S. National Science Foundation under Award No. CMMI1538416 and by the Missouri University of Science and Technology.

Publisher

Missouri University of Science and Technology

Publication Date

Spring 2018

Pagination

xiv, 155 pages

Note about bibliography

Includes bibliographic references (pages 146-154).

Rights

© 2018 Hongya Qu, All rights reserved.

Document Type

Dissertation - Open Access

File Type

text

Language

English

Thesis Number

T 11503

Electronic OCLC #

1104294869

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