Condition assessment of GFRP-retrofitted concrete cylinders using electromagnetic waves
Name
263936545-MIT.pdf
Description
Full printable version
Size
10.87 MB
Format
Adobe PDF
Checksum (MD5)
418aa56e6162fdb741f84c96f902c00b
Author(s)
Yu, Tzu-Yang (Tzu-Yang Young), 1973-
Advisor(s)
Oral Buyukozturk.
Alternative Title
Condition assessment of glass fiber reinforced polymer-retrofitted concrete cylinders using electromagnetic waves
Date Issued
2008
Publisher
Massachusetts Institute of Technology
Abstract
The objective of this study is to develop an integrated nondestructive testing (NDT) capability, termed FAR NDT (Far-field Airborne Radar NDT), for the detection of defects, damages, and rebars in the near-surface region of glass fiber reinforced polymer (GFRP)-retrofitted concrete cylinders through the use of far-field radar measurements (electromagnetic or EM waves). In this development, two far-field monostatic ISAR (inverse synthetic aperture radar) measurement schemes are identified for collecting radar measurements, and the backprojection algorithm is applied for processing radar measurements into spatial images for visualization and condition assessment. Reconstructed images are further analyzed by mathematical morphology to extract a numerical index representing the feature of the image as a basis for quantitative evaluation. The components of the development include dielectric modeling of materials, laboratory radar measurements, numerical simulation, and image reconstruction. It is found that using the developed technique the presence of near-surface defects can be detected by the oblique incidence measurements. Radar signals in the frequency range of 8 GHz to 18 GHz are found effective for damage detection in the near-surface region of the specimens. Numerical simulation using the finite-difference time-domain (FDTD) method is conducted to understand the propagation and scattering of EM waves from the defects and inclusions in two-dimensional and three-dimensional GFRP-concrete models. The FDTD simulation is capable of predicting the far-field response of GFRP-concrete cylinders and beneficial to better understanding the pattern of field measurements in the application of the FAR NDT technique.
(cont.) Dielectric properties of materials are investigated for their use in numerical simulation and for improving the precision of reconstructed images. Reconstructed images of GFRP-concrete cylinders with and without artificial features (rebar and defect) clearly indicate the presence of these features. Normal incidence scheme is found to be effective for rebar detection, and the oblique incidence scheme can discover near-surface defects such as GFRP debonding and delamination. The proposed FAR NDT technique is found to be capable of detecting near-surface defects in GFRP-concrete cylinders and potentially applicable for the field condition assessment of GFRP-retrofitted reinforced concrete and other reinforced concrete civil infrastructure systems.
Description
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 2008.
This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Includes bibliographical references (p. 343-370).
Subjects
Civil and Environmental Engineering.
MIT Department
Massachusetts Institute of Technology. Department of Civil and Environmental Engineering
Terms of Use
M.I.T. theses are protected by
copyright. They may be viewed from this source for any purpose, but
reproduction or distribution in any format is prohibited without written
permission. See provided URL for inquiries about permission.
copyright. They may be viewed from this source for any purpose, but
reproduction or distribution in any format is prohibited without written
permission. See provided URL for inquiries about permission.
Persistent DSpace Link
