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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

Concrete—Cracking
LTBP Protocol # FLD-DC-VIC-005


1.

Data Collected

 
1.1 Description and location of cracking of concrete bridge elements, including the deck, superstructure, and substructure.  

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 Crack comparison cards (gage).  
2.1.5 Tape measure.  
2.1.6 6-ft folding rule.  
2.1.7 Measuring wheel.  
2.1.8 Laser measuring device (optional).  
2.1.9 Plumb bob.  
2.1.10 Slide caliper.  
2.1.11 Hand compass or other angle-measuring device.  
2.1.12 Level.  
2.1.13 Wire brush or hand broom.  
2.1.14 Waders.  
2.1.15 Small boat.  
2.1.16 Temporary marker.  
2.1.17 Digital camera.  
2.1.18 Pencil, sketch pad, and clipboard.  
2.2 Personnel: PRE-PL-LO-005, Personnel Qualifications  

3.

Methodology

 
3.1 Use the data collection grid (FLD-OP-SC-001, Data Collection Grid and Coordinate System for Bridge Decks) to locate defects on the deck.  
3.2 Use the segmentation and numbering system (FLD-OP-SC-002, Structure Segmentation and Element Identification System) to locate and document defects by unique element identifier.  
3.3 Use FLD-OP-SC-003, Determination of Local Origins for Elements, to establish a local origin on each element on the superstructure and substructure.  
3.4 Cleaning: Use the wire brush or hand broom to clean the concrete element by brushing away any debris so any cracks are visible.  
3.5 On reinforced concrete elements, including decks, for individual cracks with a width equal to or greater than 0.025 inches at the point of the widest opening:  
3.5.1 Mark the ends of the cracks on the bridge component with a temporary marker, and photograph.  
3.5.2 If the crack is on the deck, record the location of the beginning and the end of each crack using (x,y) coordinates from the rectangular grid system following FLD-OP-SC-001, Data Collection Grid and Coordinate System for Bridge Decks. The database calculates the orientation of each crack using the (x,y) coordinates.  
3.5.3 For cracks on other concrete components (other than round pier columns), document the unique element identifier of the superstructure or substructure element on which the crack is located. Use FLD-OP-SC‑003, Determination of Local Origins for Elements, to establish a local origin on each element, and document the beginning and ending points of the crack using the (x,y,z) coordinates.  
3.5.3.1 If the crack is on a round concrete pier column, using the local element origin as point (0,0), determine and record the (z,c) coordinates of the beginning and ending points of the crack.  
3.5.4 Record the length of the crack (from one end to the other in a straight line) in decimal inches using the tape measure, measuring wheel, and/or laser measuring device.  
3.5.5 Record the orientation of the crack (degrees) using a plump bob, compass, or other angle-measuring device.  
3.5.6 Measure the maximum crack width (opening) with the crack comparison card (crack gage).  
3.5.7 If possible, measure or estimate the maximum depth of the crack.  
3.5.8 Identify and record other crack characteristics (if any), such as presence of moisture, efflorescence, rust, or exposed rebar.  
3.5.9 In prestressed concrete bridge structural elements, if the crack exceeds the width of 0.005 inches, then the team leader should notify the bridge owner and Federal Highway Administration (FHWA) Long-Term Bridge Performance (LTBP) Program.  
3.6 On prestressed concrete elements, for individual cracks with a width equal to or greater than 0.005 inches at the point of the widest opening:  
3.6.1 Mark the ends of the cracks on the bridge component with a temporary marker, and photograph.  
3.6.2 Document the unique element identifier of the element on which the crack is located. Use FLD-OP-SC-003, Determination of Local Origins for Elements, to establish a local origin on each element and document the beginning and ending points of the crack using the (x,y,z) coordinates.  
3.6.3 Record the length of the crack (from one end to the other in a straight line) in decimal inches using the tape measure, measuring wheel, and/or laser measuring device.  
3.6.4 Record the orientation of the crack (degrees) using a plump bob, compass, or other angle- measuring device.  
3.6.5 Measure the maximum crack width (opening) with the crack comparison card (crack gage).  
3.6.6 If possible, measure or estimate the maximum depth of the crack.  
3.6.7 Identify and record other crack characteristics (if any), such as presence of moisture, efflorescence, rust, or exposed rebar.  
3.6.8 In prestressed concrete bridge structural elements, if the crack exceeds the width of 0.006 inches, then the team leader should notify the bridge owner and FHWA LTBP.  
3.7 For crack networks (also known as alligator cracking, area cracking, map cracking, or crazing):  
3.7.1 Treat the area of cracking as a single defect in the same manner as area defects, such as scaling, delamination, etc.  
3.7.2 Outline the boundaries of the network cracking on the concrete surface with a temporary marker and photograph it. Document all visible cracks with sketches and/or photographs (FLD-DC-PH‑002, Photographing for Documentation Purposes) that capture the entire area. Also, mark the corners of a rectangle that encompasses the maximum length and maximum width of the area of network cracking.  
3.7.3 Measure and record the dimensions of each area of network cracking at its maximum length and width.  
3.7.3.1 If the area of network cracking is on the deck, determine and record the coordinates of the four corners of the rectangle using (x,y) coordinates from the rectangular grid system created using FLD-OP-SC-001, Data Collection Grid and Coordinate System for Bridge Decks.  
3.7.3.2 For each area of network cracking on other concrete elements (other than round pier columns), document on which superstructure or substructure element and on what area of the element the area of network cracking is located. Using the element local origin as point (0,0,0), determine and record the (x,y,z) coordinates of the four corners of the rectangle.  
3.7.3.3 If the area of network cracking is on a round concrete pier column, using the local element origin as point (0,0), determine and record the (z,c) coordinates of the four corners of the rectangle.  
3.7.4 If possible, measure or estimate the maximum depth of the cracks.  
3.7.5 Identify and record other crack characteristics (if any), such as presence of moisture, efflorescence, rust, or exposed rebar.  
3.8 For areas that show signs of moisture or efflorescence:  
3.8.1 Treat the area of moisture or efflorescence as a single defect in the same manner as area defects, such as scaling, delamination, etc.  
3.8.2 Outline the boundaries of the moisture or efflorescence on the concrete surface with a temporary marker, and photograph it. Also, mark the corners of a rectangle that encompasses the maximum length and maximum width of the area of moisture or efflorescence.  
3.8.3 Measure and record the dimensions of each area of moisture or efflorescence at its maximum length and width.  
3.8.3.1 If the area of moisture or efflorescence is on the deck, determine and record the coordinates of the four corners of the rectangle using (x,y) coordinates from the rectangular grid system created using FLD-OP-SC-001, Data Collection Grid and Coordinate System for Bridge Decks.  
3.8.3.2 For each area of moisture or efflorescence on other concrete elements (other than round pier columns), document which superstructure or substructure element and on what area of the element the area of network cracking is located. Using the element local origin as point (0,0,0), determine and record the (x,y,z) coordinates of the four corners of the rectangle.  
3.8.3.3 If the area of moisture or efflorescence is on a round concrete pier column, using the local element origin as point (0,0), determine and record the (z,c) coordinates of the four corners of the rectangle.  
3.9 Documenting defects:  
3.9.1 Take photographs of cracking using FLD-DC-PH-002, Photographing for Documentation Purposes, and create a photo log.  
3.9.2 Use sketches as needed to document cracking and supplement the photographs.  
3.10 Storing data, documents, and images:  
3.10.1 FLD-DS-LS-001, Data, Document, and Image Storage—Local, for local storage.  
3.10.2 FLD-DS-RS-001, Data, Document, and Image Storage—Remote, for remote storage.  
3.11 Reporting: Transfer all metadata, data, documents, and images to FHWA, and/or upload all metadata, data, documents, and images into the 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 Individual Cracks on the Concrete Deck or Other Concrete Element
Pink
8 Location of crack: span number
Text
 
 
Evaluate each span individually and record data on each individual crack
Blue
9 Location of crack: element type and unique identifier
Text
 
 
Record the bridge element containing the crack (for example, deck, abutment, girder)
Blue
10 Location of crack on the deck or element
Text
 
 
Describe the location of crack on the bridge element (for example, lane number, right or left shoulder, substructure unit, backwall of abutment, web of prestressed concrete girder, etc.)
Blue
11 Location of the beginning of the crack
Number
1
in.

On the deck: (x,y) coordinates of the ends of the crack
On other concrete elements: (x,y,z) coordinates of the ends of the crack

Yellow
12 Location of the end of the crack
Number
1
in.
Yellow
13 Maximum crack depth
Number
0.125
in.
If measurable
Yellow
14 Maximum crack width (opening)
Number
See note
in.
Note: required accuracy depends on the maximum crack width; see section 6.4.3
Yellow
15 Crack length
Number
1
in.
Measured in a straight line from the beginning to the end of crack
Yellow
16 Crack orientation
Number
1
Degrees
 
Yellow
17 Other crack characteristics
Text
 
 
Indicate presence of moisture, efflorescence, rust, exposed rebar, or other (specify under comments)
Yellow
18 Photos or sketches of individual cracks
BLOB
 
 
Document each crack with photo(s) or sketch(es)
Yellow
19 Comments
Text
 
 
 
Orange
For Crack networks on the Concrete Deck or Other Concrete Element
Pink
20 Location of crack network: span number
Text
 
 
Evaluate each span individually and record data on each individual crack network
Blue
21 Location of crack network: element type and unique identifier
Text
 
 
Record the bridge element containing the crack network (for example, deck, abutment, girder)
Blue
22 Location of crack network on the deck or element
Text
 
 
Describe the location of crack network on the bridge element (e.g., lane number, right or left shoulder, substructure unit, backwall of abutment, web of prestressed concrete girder, etc.)
Blue
23 Location of corner 1
Number
1
in.

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

Yellow
24 Location of corner 2
Number
1
in.
Yellow
25 Location of corner 3
Number
1
in.
Yellow
26 Location of corner 4
Number
1
in.
Yellow
27 Maximum crack depth
Number
0.125
in.
If measurable
Yellow
28 Maximum crack width (opening)
Number
See note
in.
Note: required accuracy depends on the maximum crack width; see section 6.4.3
Yellow
29 Crack length
Number
1
in.
Maximum length (opening) of the longest continuous crack
Yellow
30 Other crack characteristics
Text
 
 
Indicate presence of moisture, efflorescence, rust, or other (specify under comments)
Yellow
31 Photos or sketches of typical crack networks
BLOB
 
 
Document typical crack networks with photos or sketches
Yellow
32 Comments
Text
 
 
 
Orange
For Areas of Moisture or Efflorescence on the Concrete Deck or Other Concrete Element
Pink
33 Location of moisture or efflorescence: span number
Text
 
 
Evaluate each span individually and record data on each individual area of moisture or efflorescence
Blue
34 Location of moisture or efflorescence: element type and unique identifier
Text
 
 
Record the bridge element containing the moisture or efflorescence (for example deck, abutment, girder)
Blue
35 Location of moisture or efflorescence on the deck or element
Text
 
 
Describe the location of moisture or efflorescence on the bridge element (e.g., lane number, right or left shoulder, substructure unit, backwall of abutment, web of prestressed concrete girder, etc.)
Blue
36 Location of corner 1
Number
1
in.
(x,y) coordinates of the four corners of a rectangle encompassing the deteriorated area
Yellow
37 Location of corner 2
Number
1
in.
Yellow
38 Location of corner 3
Number
1
in.
Yellow
39 Location of corner 4
Number
1
in.
Yellow
40 Photos or sketches of typical crack networks
BLOB
 
 
Document typical crack networks with photos or sketches
Yellow
41 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 that 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 provides guidance on locating individual cracks as well as areas of map cracking on concrete elements. Instructions are provided for documenting the location, orientation, width, and depth (if possible) of individual cracks and the location and extent of areas of map cracking.  
6.2 Cracks may be due to the following:  
6.2.1 Chemical: alkali-silica reaction (ASR); internal or external sulphate attack.  
6.2.2 Structural (live or dead loads).  
6.2.3 Steel reinforcement or prestressing corrosion.  
6.2.4 Creep or shrinkage.  
6.2.5 Ground motion.  
6.2.6 Collisions, earthquakes, or other sudden and external solicitations.  
6.3 Cracks resulting from any of the conditions in section 6.2 may lead to significant damage and are important to the performance of the element that has cracked.  
6.4 This protocol contains two different values for crack width—one value for reinforced concrete bridge members and a different value for prestressed concrete bridge members. Some States do not allow any tension in prestressed concrete bridge members (pretensioned and posttensioned). Therefore, even a small crack width in a prestressed concrete bridge member is important. States do allow some cracking in reinforced concrete bridge members, and designers assume that the rebars will carry the load in the areas of the member where tension cracks and rebars are present. Therefore, a somewhat larger crack width may be used for reinforced concrete bridge members.  
6.4.1 For reinforced concrete elements, including decks, all cracks where the maximum width of the crack is 0.025 inches or greater will be measured and recorded.  
6.4.2 For prestressed concrete bridge elements (pretensioned and posttensioned), all cracks where the maximum width of the crack is 0.005 inches or greater will be measured and recorded.  
6.4.3 The required accuracy of the crack width measurement will vary according to the maximum width of the crack. This measurement is to be made with a typical crack gage card as follows:  
6.4.3.1 Crack widths less than 0.020 inches – required accuracy is to the nearest 0.002 inches.  
6.4.3.2 Crack widths above 0.020 inches but below 0.040 inches – required accuracy is to the nearest 0.005 inches.  
6.4.3.3 Crack widths above 0.040 inches but below 1.00 inches – required accuracy is to the nearest 0.01inches.  
6.5 The LTBP Program is trying to better understand why bridges deteriorate over time, and the accurate measurement of crack widths is important for research purposes. Because of this, it is important to measure and track the locations, orientations (angles), and widths of cracks over time with sufficient scale to assist in evaluating the performance of concrete elements.  
6.6 The presence of moisture in a concrete component is typically the result of cracks in the concrete wide enough to allow water to follow a path for the full thickness of the component. Efflorescence is the result of moisture passing through concrete that leaves light-colored or brown deposits on the concrete surface where the moisture exits. The deposits are formed by a combination of the calcium carbonate leaching out of the cement and the recrystallization of carbonate and chloride compounds. The following are typical locations to look for signs of water infiltration with efflorescence:  
6.6.1 Bare deck undersides.  
6.6.2 Superstructure: headwalls and spandrel walls.  
6.6.3 Substructure: abutment breastwalls, backwalls, and wingwalls.  
6.7 This evaluation requires that the inspector has arm’s-length access to every part of the structure (arm’s-length access is the generally admitted distance from which cracks of this size are detectable).  

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-001, Data Collection Grid and Coordinate System for Bridge Decks.  
7.1.4 FLD-OP-SC-002, Structure Segmentation and Segmentation and Element System.  
7.1.5 FLD-OP-SC-003, Determination of Local Origins for Elements.  
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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