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Title: STRUCTURAL ASSESSMENT OF A CABLE-STAYED BRIDGE

Abstract

No abstract prepared.

Authors:
;
Publication Date:
Research Org.:
Los Alamos National Lab., NM (US)
Sponsoring Org.:
US Department of Energy (US)
OSTI Identifier:
788272
Report Number(s):
LA-UR-01-5691
TRN: US200202%%291
DOE Contract Number:
W-7405-ENG-36
Resource Type:
Conference
Resource Relation:
Conference: Conference title not supplied, Conference location not supplied, Conference dates not supplied; Other Information: PBD: 1 Oct 2001
Country of Publication:
United States
Language:
English
Subject:
42 ENGINEERING; BRIDGES; CABLES; SYSTEMS ANALYSIS; EVALUATION

Citation Formats

F. M. HEMEZ, and H. SOHN. STRUCTURAL ASSESSMENT OF A CABLE-STAYED BRIDGE. United States: N. p., 2001. Web.
F. M. HEMEZ, & H. SOHN. STRUCTURAL ASSESSMENT OF A CABLE-STAYED BRIDGE. United States.
F. M. HEMEZ, and H. SOHN. Mon . "STRUCTURAL ASSESSMENT OF A CABLE-STAYED BRIDGE". United States. doi:. https://www.osti.gov/servlets/purl/788272.
@article{osti_788272,
title = {STRUCTURAL ASSESSMENT OF A CABLE-STAYED BRIDGE},
author = {F. M. HEMEZ and H. SOHN},
abstractNote = {No abstract prepared.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Mon Oct 01 00:00:00 EDT 2001},
month = {Mon Oct 01 00:00:00 EDT 2001}
}

Conference:
Other availability
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  • The structural health monitoring of a large cable-stayed bridge using ambient vibration measurement is summarized. The location of the bridge cannot, at this time, be revealed for confidentiality reason. The bridge is continuously monitored with an instrumentation system that has been collecting 16 channels of acceleration, wind pressure and temperature data over the past six years. The paper focuses on the analysis of two data sets collected in June 1995 and September 2000. Nonlinear data processing techniques such as higher-order statistical and temporal moments and wavelet transforms are presented to quantify the energy content of the signals in the timemore » and frequency domains. Then, linear modal models are fit to the data in order to translate the changes observed in terms of stiffness reduction or damping increase. It is concluded that structural change takes the form of a reduction in stiffness rather than an increase in damping. The discussion also illustrates typical issues encountered in structural health monitoring applications. These include collecting non-stationary signals, investigating a nonlinear response and dealing with environmental variability and changing operating conditions.« less
  • Dual-band infrared (DBIR) thermal imaging is a promising, non-contact, nondestructive evaluation tool to evaluate the amount of deteriorated concrete on asphalt-covered bridge decks. We conducted proof-of-principle demonstrations to characterize defects in concrete structures which could be detected with DBIR thermal imaging. We constructed two identical concrete slabs with synthetic delaminations, e.g., 1/8-in. thick styrofoam squares, implanted just above the 2-in.-deep steel reinforcement bars. We covered one of the slabs with a 2-in. layer of asphalt. We mounted the DBIR cameras on a tower platform, to simulate the optics needed to conduct bridge-deck inspections from a moving vehicle. We detected 4-in.more » implants embedded in concrete and 9-in. implants embedded in asphalt-covered concrete. The midday (above-ambient) and predawn (below-ambient) delamination-site temperatures correlated with the implant sizes. Using DBIR image ratios, we enhanced thermal-contrast and removed emissivity-noise, e.g., from concrete compositional variations and clutter. Using the LLNL/VIEW code, we removed the asphalt thermal-gradient mask, to depict the 4-in. deep, 9-in. square, concrete implant size. We plan to image bridge deck defects, from a moving vehicle, for accurate estimations of the amount of deteriorated concrete impairing the deck integrity. Potential longterm benefits are affordable and reliable rehabilitation for asphalt-covered decks.« less
  • Issues surrounding the use of ambient vibration modes for the location of structural damage via dynamically measured flexibility are examined. Several methods for obtaining the required mass- normalized dynamic mode shapes from ambient modal data are implemented and compared. The method are applied to data from a series of ambient modal tests on an actual highway bridge. Results indicate that for the damage case examined, the flexibility from the ambient mode shapes gave a better indication of damage than the flexibility from the forced-vibration mode shapes. This improved performance is attributed to the higher excitation load levels that occur duringmore » the ambient test.« less
  • Abstract not provided.