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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—Section Loss
LTBP Protocol #: FLD-DC-VIS-003


1.

Data Collected

 
1.1 Description and location of steel section loss 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 Sounding hammer.  
2.1.4 Tape measure.  
2.1.5 6-ft folding rule.  
2.1.6 Scraper.  
2.1.7 Crack comparison card.  
2.1.8 Wire brush or hand broom.  
2.1.9 Slide calipers.  
2.1.10 Web calipers.  
2.1.11 Straight edge or ruler.  
2.1.12 Ultrasonic thickness gage.  
2.1.13 Digital camera.  
2.1.14 Temporary marker.  
2.1.15 Laser measuring device (optional).  
2.1.16 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.  
3.3 Cleaning:  
3.3.1 Use a scraper and/or a hammer to remove exfoliated steel at suspect areas until the base metal is uncovered.  
3.3.2 With a wire brush, clear away loose metal and other debris, if necessary, to allow accurate measurements and photographs.  
3.4 Measuring, recording, and evaluating characteristics of section loss:  
3.4.1 After removing all loose material from the surface, mark the limits of the section loss. Measure the remaining thicknesses of the reduced section with slide calipers or ultrasonic thickness gage. Measure the initial thickness of the element cross section, and calculate the percentage of section remaining.  
3.4.1.1 Measure flange thickness with slide calipers.  
3.4.1.2 Measure web thicknesses with web calipers if feasible. If is not feasible, use an ultrasonic thickness gage on the web; as a last alternative, estimate the loss of thickness using a straight edge and ruler.  
3.4.2 Sample areas of section loss to determine the maximum value of loss (minimum remaining section). To do this, use calipers, or ultrasonic thickness gage. The as-built construction plans can be used to obtain the original thickness of the member at a location where there is no loss of section.  
3.4.3 Mark the limits of each area of section loss on the element with a temporary marker and also mark the corners of a rectangle that encompasses the maximum length and maximum width of the area of section loss.  
3.4.3.1 Using the element local origin as point (0,0,0), determine and record the coordinates of the four corners of the rectangle.  
3.4.3.2 Measure the length and width of each area of section loss with a tape measure.  
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 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
8 Date data were collected
Text
Exact date
 
mm/dd/yyyy
Green
9 Location of section loss: element type and unique identifier
Text
 
 
Example: Girder, 1A; evaluate and record data for areas with section loss on each individual element
Blue
10 Location of defect on the element
Text
 
 
Example: web of girder 1A
Blue
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 section loss
Number
1
in.
 
Yellow
16 Maximum width of section loss
Number
1
in.
 
Yellow
17 Minimum remaining thickness
Number
0.0625
in.
 
Yellow
18 Original thickness
Number
0.0625
in.
 
Yellow
19 Defect photos
BLOB
 
 
If defects are present, document typical defects with photos and/or sketches
Yellow
20 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 appropriate protocols.  

6.

Commentary/Background

 
6.1 This protocol describes the evaluation of steel with section loss, oxidation, or rusting.  
6.2 After a period of exposure to water, salts, and chemical agents, load and/or other factors, advanced deterioration of steel may result in material section loss that can ultimately lead to a perforated section.  
6.3 Data collection involves exposing the areas where section loss has occurred, removing all loose materials, and then determining the thickness of the steel and the amount of the original section still remaining 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-PH-002, Photographing for Documentation Purposes.  
7.1.6 FLD-DS-LS-001, Data, Document, and Image Storage—Local.  
7.1.7 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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