Primer for the Inspection and Strength Evaluation of Suspension Bridge Cables

Primer for the Inspection and Strength Evaluation of Suspension Bridge Cables
Title:
Primer for the Inspection and Strength Evaluation of Suspension Bridge Cables
Format:
Paperback
USA Price: 
$26.00
$13.00
Display Foreign Price
Stock:
In stock
GPO Stock Number:
050-002-00114-1
ISBN:
9780160913099
Description

This Primer serves as an initial resource for planning and performing inspection, metallurgical testing, and strength evaluation of suspension bridge cables. Included are an of a simplified strength evaluation, flowcharts illustrating the inspection and strength evaluation procedures, and inspection and strength evaluation forms that can be used or replicated by bridge inspectors and engineers. FHWA Publication No. FHWA-IF-11-045.

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Table of Contents

Table of Contents

FOREWORD ................................................................................................................................. 1
ACKNOWLEDGEMENTS ............................................................................................................ 2
1.0 Introduction ............................................................................................................................ 3
1.1 Documents ....................................................................................................................... 3
1.2 Primer Organization ......................................................................................................... 3
1.3 Suspension Bridge Cables................................................................................................ 4
1.3.1 Bridge Cable Components ...................................................................................... 5
1.3.2 Bridge Cable Protection .......................................................................................... 9
1.3.3 Causes of Cable Deterioration .............................................................................. 10
1.3.4 Cable Wire Corrosion ........................................................................................... 11
2.0 Inspection Guidelines and Laboratory Testing Methods ..................................................... 14
2.1 Cable Inspection............................................................................................................. 14
2.1.1 Levels of Inspection and Inspection Intervals ...................................................... 15
2.1.1.1 Inspections by Maintenance Personnel ............................................... 15
2.1.1.2 Biennial Inspections ............................................................................ 15
2.1.1.3 Internal Inspections ............................................................................. 21
2.1.2 Outline of Internal Inspections.............................................................................. 29
2.1.3 Outline of Inspection and Sampling ..................................................................... 30
2.1.4 Splicing of New Wires into the Cable .................................................................. 31
2.2 Cable Inspection............................................................................................................. 32
2.2.1 Tests of Wire Properties........................................................................................ 32
2.2.1.1 Specimen Preparation ......................................................................... 32
2.2.1.2 Tensile Tests ....................................................................................... 33
2.2.1.3 Obtaining Data for Stress vs. Strain Curves ....................................... 33
2.2.1.4 Fractographic Examination of Suspect Wires ..................................... 33
2.2.1.5 Examination of Fracture Surface for Pre-existing Cracks .................. 34
2.2.2 Zinc Coating Tests ................................................................................................ 34
2.2.2.1 Weight of Zinc Coating ...................................................................... 35
2.2.2.2 Preece Test for Uniformity ................................................................. 35
2.2.3 Chemical Analysis ................................................................................................ 35
2.2.4 Corrosion Analysis................................................................................................ 36
3.0 Evaluation of Field and Laboratory Data overview ............................................................. 37
3.1 Mapping and Estimating Wire Deterioration ................................................................. 37
3.1.1 Number of Rings in the Cable .............................................................................. 37
3.1.2 Number of Wires in Each Ring ............................................................................. 38
3.1.3 Wire Deterioration/Corrosion Mapping ................................................................ 38
3.1.4 Fraction of Cable in Each Corrosion Stage........................................................... 40
3.1.5 Number of Broken Wires ...................................................................................... 41
3.2 Wire Properties .............................................................................................................. 42
3.2.1 Cracked Wires as a Separate Group ...................................................................... 42
3.2.2 Individual Wire Properties .................................................................................... 43
3.2.2.1 Mean Properties .................................................................................. 43
3.2.2.2 Minimum Properties in a Panel Length .............................................. 44
3.2.3 Wire Group Mean Strength and Standard Deviation ............................................ 45
3.3 Wire Redevelopment ..................................................................................................... 45
4.0 Estimation of Cable Strength ............................................................................................... 46
4.1 Wire Groupings .............................................................................................................. 47
4.2 Strength of Unbroken Wires .......................................................................................... 47
4.2.1 Simplified Strength Model .................................................................................... 47
4.2.1.1 Mean Tensile Strength of Uncracked Wires ....................................... 48
4.2.1.2 Cable Strength Using the Simplified Model ....................................... 48
4.2.2 Brittle-Wire Strength Model ................................................................................. 49
4.2.3 Limited Ductility Strength Model ......................................................................... 50
4.3 Non-applicability of Load and Resistance Factor Rating (LRFR) ................................ 51
5.0 Inspection Documentation, Reporting, and Recommendations ........................................... 52
5.1 Maintenance Personnel Inspection Reports ................................................................... 52
5.2 Biennial Inspection Report ............................................................................................ 52
5.3 Internal Inspection Report.............................................................................................. 53
6.0 References ............................................................................................................................ 55
7.0 Appendix A: Strength Evaluation Example ........................................................................ 56
7.1 Prior to Inspection .......................................................................................................... 57
7.1.1 Number of Wires in the Cable .............................................................................. 57
7.1.2 Number of Rings in the Cable .............................................................................. 57
7.1.3 Number of Wires in Each Ring ............................................................................. 59
7.2 Analyzing Inspection Data ............................................................................................. 60
7.2.1 Corrosion Map ...................................................................................................... 63
7.2.2 Broken and Removed Wires for Testing .............................................................. 64
7.2.3 Number of Wires in Each Corrosion Stage ........................................................... 65
7.3 Analyzing Laboratory Testing Data ............................................................................... 69
7.3.1 Test data for Wire Number 609 ............................................................................ 69
7.3.2 Test Data for Wire Number 613 ........................................................................... 71
7.3.3 Summary of all Test Data ..................................................................................... 72
7.3.4 Cracked Wires as a Separate Group ...................................................................... 75
7.4 Cable Strength Evaluation – Simplified Model ............................................................. 75
7.4.1 Estimate of Number of Broken Wires in the Development Length (Panel) ......... 76
7.4.2 Cracked Wires in the Evaluated Panel .................................................................. 77
7.4.3 Estimate of Cable Strength ................................................................................... 78
8.0 Appendix B: Previous Inspection References ..................................................................... 82
9.0 Appendix C: Flowcharts ..................................................................................................... 83
9.1 Inspection Flowchart ...................................................................................................... 83
9.2 Strength Evaluation Flowchart ...................................................................................... 84
10.0 Appendix D: Inspection and Evaluation Forms ............................................................. 85
10.1 Inspection Forms ............................................................................................................ 85
10.2 Strength Evaluation Forms ............................................................................................ 93
11.0 Appendix E: BTC Method for Evaluation of Remaining Strength and Service Life                                                                                                                                                                                                                                                 of Bridge Cables ................................................................................................................... 98
11.1 Introduction .................................................................................................................... 98
iv
11.2 Main Cable Inspection and Sampling ............................................................................ 99
11.2.1 Panel Selection Criterion ...................................................................................... 99
11.2.2 Random Sampling and Sample Size Determination ............................................. 99
11.2.2.1 Random Sampling and Practical Considerations .............................. 100
11.2.2.2 Sampling Size Determination ........................................................... 100
11.2.2.3 Wedge Pattern ................................................................................... 101
11.2.2.4 Sampling Frame of Random Sample ................................................ 101
11.2.3 Inspection Procedures ......................................................................................... 102
11.3 Wire Testing Program .................................................................................................. 104
11.3.1 Enhanced Tensile Strength Test in Standard Wire Specimens ........................... 104
11.3.2 Tensile Strength Test on Long Wire Specimens ................................................. 104
11.3.3 Fracture Toughness Test ..................................................................................... 104
11.3.4 Fractographic and Scanning Electron Microscope (SEM) Evaluation ............... 105
11.4 Cable Strength Evaluation ........................................................................................... 105
11.4.1 BTC Method Inputs ............................................................................................ 105
11.4.2 Choice of Probability Distributions .................................................................... 106
11.4.3 Elongation Threshold Criterion, Mthreshold ........................................................... 106
11.4.4 Determination of Wire Condition ....................................................................... 107
11.4.5 Wire Recovery Length ........................................................................................ 107
11.4.6 Broken Wires ...................................................................................................... 108
11.4.6.1 Exterior Broken Wires ...................................................................... 108
11.4.6.2 Interior Broken Wires ....................................................................... 109
11.4.7 Cracked Wires ..................................................................................................... 109
11.4.8 Strength Evaluation using the BTC Method ....................................................... 109
11.5 BTC Method Forecast of Cable Life ........................................................................... 109
11.5.1 Forecast of Degradation in Intact Wire Strength ................................................ 110
11.5.2 Forecast of Degradation in Cracked Wire Strength ............................................ 110
11.6 Sensitivity Analysis ..................................................................................................... 111
11.6.1 Key Inputs ........................................................................................................... 111
11.6.2 Sensitivity Indices ............................................................................................... 112
11.7 Appendix E References................................................................................................ 112

Audience

This publication would be most interesting and informative for engineers and bridge inspectors.

Product Details

Availability Details:
In Stock
USA Price:
$13.00
International Price:
$18.20
Publisher:
Transportation Dept., Federal Highway Administration
Key Phrases:
  • FHWA IF 11 045
  • Bridges
  • Highway Bridges
Weight:
1
Quantity Price:
Discount
Cover:
Paper
Unit of Issue (US):
1
Unit of Issue (Non-US):
1
Item available Date:
07/12/2012
Last Status Update:
01/17/2018
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