UVM Theses and Dissertations
Format:
Print
Author:
Cui, Jianhong
Dept./Program:
Mechanical Engineering
Year:
2012
Degree:
PhD
Abstract:
Concrete bridge decks are ubiquitous and important elements of most highway bridges in the US. They are high-performance structures that often pose many vexing maintenance issues. Cracks, spalling, scaling, honeycomb, voids, delamination and corrosion of rebar are most common types of discontinuities and defects that may exist in concrete bridge decks. Corrosion of rebar is one of the dominant damage types in terms of overall bridge maintenance costs. These discontinuities and defects may shorten the service life of the concrete bridge deck. Two methods has been used on bridge deck condition assessment for maintenance: destructive evaluation (DE) and nondestructive evaluation (NDE). Nondestructive evaluation is preferred because it will not jeopardize the future usage of the bridge. Early and accurate detection, location and assessment of damages in reinforced concrete bridge decks may have a positive effect in the scheduling and performance of maintenance and rehabilitation activities, especially early detection ofcorrosion can significantly reduce the damage progression and maintenance costs.
A variety of NDE techniques and methods, such as ground penetrating radar, halfcell potential and ultrasonic testing, emerged and became available during the past few decades; some of which have been applied widely for monitoring the structures, especially on concrete bridge deck. Generally speaking, these testing methods are based on the different physical principles. Each method has its own advantages and disadvantages. The accuracy, reliability and information gained with each NDE technique is not always guaranteed and differs from problem to problem. Combining information regarding the state of the structure with that regarding the quality of the information may significantly enhance the effectiveness and accuracy of the assessments that are needed for managing bridge deck maintenance. Although these NDE techniques have different advantages, no single method can detect all of the defects. Therefore multiple NDE methods are preferred.
The aim of this study is to assess and improve the ability of various NDE methods to detect the defects of concrete bridge deck. Six different NDE methods are selected and periodically applied on the laboratory concrete specimen, which is nominally similar to a typical concrete bridge deck. The testing data from these Six methods are analyzed, compared. The technique of data fusion, either image level or decision level, has been applied on the data analysis from multiple NDE data.
Based on the testing results, multiple NDE application shows some benefits on concrete bridge deck maintenance: early-stage defects, such as corrosion of rebar, can be detected; the sizes and locations of damage areas can be accurately determined and confirmed by one or several NDE methods; the fused data further proved and confirmed the defects that were detected by multiple NDE methods. The fused and enhanced data can be used in the object analysis of life cycle benefit and cost or in a performance assessment based on monitoring ofthe constructed structures.
A variety of NDE techniques and methods, such as ground penetrating radar, halfcell potential and ultrasonic testing, emerged and became available during the past few decades; some of which have been applied widely for monitoring the structures, especially on concrete bridge deck. Generally speaking, these testing methods are based on the different physical principles. Each method has its own advantages and disadvantages. The accuracy, reliability and information gained with each NDE technique is not always guaranteed and differs from problem to problem. Combining information regarding the state of the structure with that regarding the quality of the information may significantly enhance the effectiveness and accuracy of the assessments that are needed for managing bridge deck maintenance. Although these NDE techniques have different advantages, no single method can detect all of the defects. Therefore multiple NDE methods are preferred.
The aim of this study is to assess and improve the ability of various NDE methods to detect the defects of concrete bridge deck. Six different NDE methods are selected and periodically applied on the laboratory concrete specimen, which is nominally similar to a typical concrete bridge deck. The testing data from these Six methods are analyzed, compared. The technique of data fusion, either image level or decision level, has been applied on the data analysis from multiple NDE data.
Based on the testing results, multiple NDE application shows some benefits on concrete bridge deck maintenance: early-stage defects, such as corrosion of rebar, can be detected; the sizes and locations of damage areas can be accurately determined and confirmed by one or several NDE methods; the fused data further proved and confirmed the defects that were detected by multiple NDE methods. The fused and enhanced data can be used in the object analysis of life cycle benefit and cost or in a performance assessment based on monitoring ofthe constructed structures.