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REPORT
This report is an archived publication and may contain dated technical, contact, and link information
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Publication Number:  FHWA-HRT-16-007    Date:  January 2016
Publication Number: FHWA-HRT-16-007
Date: January 2016

 

Long-Term Bridge Performance (LTBP) Program Protocols, Version 1

Long-Term Bridge Performance Program Logo

Steel Superstructure—Corrosion
LTBP Protocol #: FLD-DC-VIS-002


1.

Data Collected

 
1.1 Description and location of corrosion on a steel superstructure.  

2.

Onsite Equipment and Personnel Requirements

 
2.1 Equipment:  
2.1.1 PRE-PL-LO-004, Personal Health and Safety Plan.  
2.1.2 Ladder, access platform, snooper, bucket truck, man lift, and/or high-reach equipment (if necessary).  
2.1.3 Tape measure.  
2.1.4 6-ft folding rule.  
2.1.5 Scraper.  
2.1.6 Wire brush or hand broom.  
2.1.7 Sounding hammer.  
2.1.8 Lever pit gage.  
2.1.9 Slide caliper.  
2.1.10 Laser measuring device (optional).  
2.1.11 Temporary marker.  
2.1.12 Digital camera.  
2.1.13 Pencil, sketch pad, and clipboard.  
2.2 Personnel: PRE-PL-LO-005, Personnel Qualifications.  

3.

Methodology

 
3.1 Use the segmentation and numbering system for the superstructure (FLD-OP-SC-002, Structure Segmentation and Element Identification System) so defects can be located and noted by the unique element identifier.  
3.2 Use FLD-OP-SC-003, Determination of Local Origins for Elements, to establish a local origin on each element to be used to locate defects.  
3.3 Cleaning:  
3.3.1 Use the scraper and wire brush to clean loose, deteriorated protective coating and surface corrosion, if any are present.  
3.3.2 If after cleaning, section loss to the steel is evident, follow FLD-DC-VIS-003, Steel Superstructure—Section Loss, to record measurements and characteristics of the section loss.  
3.4 Measuring, recording, and evaluating characteristics of corrosive activity:  
3.4.1 Mark the limits of each area with deteriorated coatings on the element with a temporary marker, and mark the corners of a rectangle that encompasses the maximum length and maximum width of the corroded area.  
3.4.1.1 Using the element local origin as point (0,0,0), determine and record the coordinates of the four corners of the rectangle.  
3.4.1.2 Measure the maximum length and width of the area with deteriorated coatings.  
3.4.2 Mark the limits of each corroded area on the element with a temporary marker, and mark the corners of a rectangle that encompasses the maximum length and maximum width of the corroded area.  
3.4.2.1 Using the element local origin as point (0,0,0), determine and record the coordinates of the four corners of the rectangle.  
3.4.2.2 Measure the maximum length and width of the corrosion.  
3.4.3 Determine the extent (depth) and severity of any pitting using a lever pit gage.  
3.5 Documenting defects:  
3.5.1 Take photographs of defects using FLD-DC-PH-002, Photographing for Documentation Purposes, and create a photo log.  
3.5.2 Use sketches as needed to document section loss and cracking and supplement the photographs.  
3.6 Storing data, documents, and images:  
3.6.1 FLD-DS-LS-001, Data, Document, and Image Storage—Local, for local storage.  
3.6.2 FLD-DS-RS-001, Data, Document, and Image Storage—Remote, for remote storage.  
3.7 Reporting: Transfer all metadata, data, documents, and images to Federal Highway Administration (FHWA), and/or upload all metadata, data, documents, and images into the Long-Term Bridge Performance (LTBP) Bridge Portal.  

4.

Data Collection Table

 
4.1 Table:  
# Field Name Data Type Accuracy Unit Field Description Row Color
1 State
Text
 
 
State Code; e.g., Virginia = VA
Green
2 NBI structure number
Text
 
 
Item 8, structure number; from NBI Coding Guide
Green
3 Structure name
Text
 
 
Descriptive name for the bridge; e.g., Route 15 SB over
I–66
Green
4 Protocol name
Text
 
 
Title of the protocol
Green
5 Protocol version
Text
Month and year
 
Month and year the protocol version was published; e.g., May 2015
Green
6 Personnel performing data collection activities
Text
 
 
First name(s) Last name(s)
Green
7 Date data were collected
Text
Exact date
 
mm/dd/yyyy
Green
For Coating Deterioration
Pink
8 Location of deteriorated coating: element type and unique identifier
Text
 
 
Example: Girder, 1A; evaluate and record data for areas of deteriorated coating on each individual element
Blue
9 Location of defect on the element
Text
 
 
Example: bottom flange of girder 1A
Blue
10 Type of defect
Text
 
 
Chalking
Cracking
Loss of adhesion
Peeling
Other (specify)
Yellow
11 Location of corner 1
Number
1
in.
(x,y,z) coordinates of the four corners of a rectangle encompassing the deteriorated area
Yellow
12 Location of corner 2
Number
1
in.
Yellow
13 Location of corner 3
Number
1
in.
Yellow
14 Location of corner 4
Number
1
in.
Yellow
15 Maximum length of deteriorated coating area
Number
1
in.
Measured parallel to the x-axis
Yellow
16 Maximum width of deteriorated coating area
Number
1
in.
Measured parallel to the z-axis
Yellow
17 Defect photos and sketches
BLOB
BLOB
 
Document typical areas of deteriorated coating with photos and/or sketches
Yellow
18 Comments
Text
 
 
 
Orange
For Corrosion
Pink
19 Location of corroded area: element type and unique identifier
Text
 
 
Example: Girder, 1A; evaluate and record data for corroded areas on each individual element
Blue
20 Location of defect on the element
Text
 
 
Example: web of girder 1A
Blue
21 Location of corroded area on member – corner 1
Number
1
in.

(x,y) coordinates of the four corners of a rectangle encompassing the deteriorated area

Yellow
22 Location of corner 2
Number
1
in.
Yellow
23 Location of corner 3
Number
1
in.
Yellow
24 Location of corner 4
Number
1
in.
Yellow
25 Maximum length of corroded area
Number
1
in.
Measured parallel to the x-axis
Yellow
26 Maximum width of corroded area
Number
1
in.
Measured parallel to the z-axis
Yellow
27 Depth of pitting
Number
0.01
in.
 
Yellow
28 Defect photos and sketches
BLOB
 
 
Document typical corroded areas with photos and/or sketches
Yellow
29 Comments
Text
 
 
 
Orange
4.2 Table Key:  
Column Descriptions
#
Sequential number of data item
Field Name
Data field name
Data Type
Type of data, such as text, number, predefined list, binary large object (BLOB), or PDF file
Accuracy
Accuracy to which the data are recorded
Unit
Unit in which a measurement is taken and recorded
Field Description
Commentary on the data or list of items in a predefined list
Row Color Key
Green
Data items only entered once for each protocol for each day the protocol is applied
Pink
Logical breakdown of data by elements or defect types (not always used)
Blue
Data identifying the element being evaluated or the type of defect being identified
Yellow
LTBP data reported individually for each element or defect identified
Orange
Comments on the data collection or data entered

5.

Criteria for Data Validation

 
5.1 Compare measurements with measurements from previous inspections of the same structure to make sure values make sense.  
5.2 Compare measurements with photo documentation to make sure results shown in photos are consistent with items measured.  
5.3 If an element’s condition is improved when compared to the condition documented in a previous inspection, check with the State department of transportation to determine if any maintenance, repair, and/or bridge preservation actions have occurred. If so, document these maintenance, repair, and/or bridge preservation actions using the appropriate protocols.  

6.

Commentary/Background

 
6.1 This protocol provides guidance on identifying corroded areas on steel superstructure elements and documenting their extent and location on the element. Guidance is also provided for measuring the extent and depth of any pitting of the steel is present.  
6.2 Steel superstructures, such as trusses (deck, through, and pony), multigirder beams, girder/floor beam/stringer systems, box girders, etc., that are not built of weathering steel and are not protected by galvanizing or metallizing are usually protected by one or more coats of paint to guard against oxidation (rusting) of the steel.  
6.3 The most common types of defects in bridge coatings include chalking, cracking, loss of adhesion, and peeling. Data collection involves identifying areas where coating defects are evident and documenting the location and size of the affected areas.  
6.4 The main cause of steel corrosion in coated bridges is the lack and/or breakdown of the protective coating. Once this occurs, the exposure to corrosive agents (water, salts, and chemicals) begins a disintegration process on the surface metal. Corrosion grows from a few, small starting points, and then expands as steel molecules that are directly in contact with the corroded area also corrode; eventually, small, medium, and large contiguous areas of corrosion are evident. Data collection involves identifying areas where corrosion is evident and documenting the location and size of the affected areas.  

7.

References

 
7.1 LTBP Protocols:  
7.1.1 PRE-PL-LO-004, Personal Health and Safety Plan.  
7.1.2 PRE-PL-LO-005, Personnel Qualifications.  
7.1.3 FLD-OP-SC-002, Structure Segmentation and Element Identification System.  
7.1.4 FLD-OP-SC-003, Determination of Local Origins for Elements.  
7.1.5 FLD-DC-VIS-003, Steel Superstructure—Section Loss.  
7.1.6 FLD-DC-PH-002, Photographing for Documentation Purposes.  
7.1.7 FLD-DS-LS-001, Data, Document, and Image Storage—Local.  
7.1.8 FLD-DS-RS-001, Data, Document, and Image Storage—Remote.  
7.2 External:  
7.2.1 FHWA-NHI-12-053, Bridge Inspector’s Reference Manual, Federal Highway Administration, Washington, DC, 2012.  

 

 

 

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