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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

Determination of Local Origins for Elements
LTBP Protocol #: FLD-OP-SC-003

1.

Data Collected

  
1.1 This protocol provides guidance for locating local origins for data collection on bridge elements other than the deck, deck overlay, or approach slabs.  
1.2 Descriptions, sketches, and/or photographs of the local element origins.  

2.

Onsite Equipment and Personnel Requirements

  
2.1 Equipment:  
2.1.1 PRE-PL-LO-004, Personal Health and Safety Plan.  
2.1.2 Temporary marker.  
2.1.3 Digital camera.  
2.1.4 Pen, sketch pad, and clipboard.  
2.2 Personnel: PRE-PL-LO-005, Personnel Qualifications.  

3.

Methodology

  
3.1 Identify the origin of the rectangular local coordinate system and the data collection grid for the deck (FLD-OP-SC-001, Data Collection Grid and Coordinate System for Bridge Decks).  
3.2 Segment the bridge, the superstructure, and substructure into individual elements such as girders, abutments, bearings, etc. Identify each element with a unique element identifier (FLD‑OP‑SC‑002, Structure Segmentation and Element Identification System).  
3.3 Identify a local origin on each individual element to be evaluated; use this point for locating defects on the element. There are three directions of the triaxial coordinate system that originate at each element local origin:  
3.3.1 X – Longitudinal along the bridge.  
3.3.2 Y – Transverse to the direction of travel.  
3.3.3 Z – Vertical.  
3.4 Establish the local element origins as follows:  
3.4.1 Girders: Establish the local origin for girders at the end of the girder nearest to the deck origin in the “X” direction, as shown in figures 1 through 4.  

This illustration shows an isometric view of a steel beam section, truncated by break lines. A three-dimensional local origin is shown on the bottom right corner of the bottom flange. The x-axis is along the length of the beam. The y-axis is transverse to the beam. The z-axis is in the vertical direction. On the web of the beam a crack is shown, identified by an arrow. The ends of the crack are labeled with a pair of coordinates that take the form (x,y,z). On the top face of the bottom flange, an area of section loss is identified by an arrow. The extents of the area of section loss are estimated with a rectangle, the corners of which are labeled by coordinates that take the form (x,y,z).

Figure 1. Illustration. Location of Local Element Origin and Defect Coordinates on Steel I-Beam – Isometric View.

This illustration shows an elevation view of a steel beam section, truncated by a break line. A two-dimensional local origin is shown on the bottom left corner of the bottom flange. The x-axis is along the length of the beam. The z-axis is in the vertical direction. On the web of the beam a crack is shown, identified by an arrow. The ends of the crack are labeled with a pair of coordinates that take the form (x,y,z).

Figure 2. Illustration. Location of local element origin and defect coordinates on steel I-beam—elevation view.

This illustration shows an isometric view of a concrete beam section, truncated by break lines. A three-dimensional local origin is shown on the bottom right corner of the bottom flange. The x-axis is along the length of the beam. The y-axis is transverse to the beam. The z-axis is in the vertical direction. On the web of the beam a crack is shown, identified by an arrow. The ends of the crack are labeled with a pair of coordinates that take the form (x,y,z). On the top face of the bottom flange, an area of spall is identified by an arrow. The extents of the area of the spall are estimated with a rectangle, the corners of which are labeled by coordinates that take the form (x,y,z).

Figure 3. Illustration. Location of Local Element Origin and Defect Coordinates on Concrete I-Beam – Isometric View.

This illustration shows an elevation view of a concrete beam section, truncated by a break line. A two-dimensional local origin is shown on the bottom left corner of the bottom flange. The x-axis is along the length of the beam. The z-axis is in the vertical direction. On the web of the beam a crack is shown, identified by an arrow. The ends of the crack are labeled with a pair of coordinates that take the form (x,y,z).

Figure 4. Illustration. Location of Local Element Origin and Defect Coordinates on Concrete I-Beam – Elevation View.

3.4.2 Diaphragms: Establish the local origin for the diaphragms at the point nearest to the deck origin in the “Y” direction and at the lowest point possible on the diaphragm in the “Z” direction. When locating defects on the diaphragm, ignore the effects of skew on the x-coordinate.  
3.4.3 Secondary members: Establish the local origin for all secondary members following the same scheme as the diaphragms. If the members are in plane with the deck, then the y- and x- coordinates of the local origin will be closest to the deck origin as possible.  
3.4.4 Girder bays: Establish the local origin for girder bays (stay-in-place forms, or exposed deck undersides) at a point on the underside of the forms or the exposed deck nearest to the deck origin in the “X” and “Y” directions.  
3.4.5 Overhangs: Establish the local origin for overhangs at a point on the underside of the nearest to the deck origin in the “X” and “Y” directions.  
3.4.6 Abutments: Establish the local origin for abutment A on the top of the abutment cap at the point closest to the deck origin in the “X” and “Y” directions (figure 5). Establish the local origin for abutment B on the top of the abutment cap at the point farthest from the deck origin in the “X” and “Y” directions.  

This illustration shows a partial section view of an example bridge. The section view contains a deck with a barrier, resting on three I-Beam girders. The girders are resting on three pedestals, which are on a beam seat on an abutment. To the left of the abutment wall, a wingwall is shown. The origin is identified at top left corner of the abutment wall and the beam seat shelf, at the same elevation of the bottom of the pedestals. The y-axis is in the direction transverse to the roadway, and the z-axis is in the vertical direction.

Figure 5. Illustration. Location of local element origin on abutment stem.
3.4.7 Pier caps: Establish the local origin for pier caps at the bottom corner closest to the deck origin in the “X” and “Y” directions. Locate defects by using the two directions that are in the plane of each face of the pier cap or pier. For example, defects on the top of the pier cap will be located in global “X” and “Y” directions, with the “Z” coordinate value remaining constant regardless of skew or super elevations. Figures 6 through 9 illustrate the location of the origin on typical pier elements.  

This illustration shows an isometric view of a rectangular pier cap and rectangular column. A three-dimensional origin is located on the bottom left corner of the end of the pier cap. The x-axis is through the thickness of the pier cap, along the longitudinal direction of travel. The y-axis is along the width of the pier cap, perpendicular to the longitudinal direction of travel. The z-axis is in the vertical direction. On the right face of the pier cap, a crack is indicated by an arrow. The ends of the crack are labeled with a pair of coordinates that take the form (x,y,z). On the top face of the pier cap, an area of spall is identified by an arrow. The extents of the area of the spall are estimated with a rectangle, the corners of which are labeled by coordinates that take the form (x,y,z).

Figure 6. Illustration. Location of Local Element Origin and Defect Coordinates on Pier Cap with Square End – Isometric View.

This illustration shows a plan view of a concrete beam section, truncated by a break line. A two-dimensional local origin is shown on the top left corner of the pier cap. The x-axis is through the thickness of the pier cap. The y-axis is along the width of the pier cap, perpendicular to the longitudinal direction of travel. On the pier cap a spall is shown, identified by an arrow. The extents of the area of the spall are estimated with a rectangle, the corners of which are labeled by coordinates that take the form (x,y,z).

Figure 7. Illustration. Location of local element origin and defect coordinates on pier cap with square end—plan view.

This illustration shows an isometric view of a rectangular pier cap with a rounded end and rectangular column. A three-dimensional origin is located on the bottom left corner of the end of the pier cap where the rounded portion terminates and becomes straight. The x-axis is through the thickness of the pier cap, along the longitudinal direction of travel. The y-axis is along the width of the pier cap, perpendicular to the longitudinal direction of travel. The z-axis is in the vertical direction. On the right face of the pier cap, a crack is indicated by an arrow. The ends of the crack are labeled with a pair of coordinates that take the form (x,y,z). On the top face of the pier cap, an area of spall is identified by an arrow. The extents of the area of the spall are estimated with a rectangle, the corners of which are labeled by coordinates that take the form (x,y,z).

Figure 8. Illustration. Location of Local Element Origin and Defect on Pier Cap with Rounded End – Isometric View.

This illustration shows a plan view of a concrete beam section, truncated by a break line. A two-dimensional local origin is shown on the top left corner of the pier cap where the rounded portion terminates and becomes straight. The x-axis is through the thickness of the pier cap. The y-axis is along the width of the pier cap, perpendicular to the longitudinal direction of travel. On the pier cap a spall is shown, identified by an arrow. The extents of the area of the spall are estimated with a rectangle, the corners of which are labeled by coordinates that take the form (x,y,z).

Figure 9. Illustration. Location of Local Element Origin and Defect Coordinates on Pier Cap with Rounded End – Plan View.
3.4.8 Rectangular pier columns: Establish the local origin for rectangular pier columns at the top corner of the exposed length of the column closest to the deck origin in all three directions (figure10).  

This illustration shows an isometric view of a rectangular pier cap and rectangular column. A three-dimensional origin is located on the top left corner of the pier cap column at the interface with the underside of the pier cap. The x-axis is through the thickness of the pier cap, along the longitudinal direction of travel. The y-axis is along the width of the pier cap, perpendicular to the longitudinal direction of travel. The z-axis is in the vertical direction downward. On the front face of the pier cap column, a crack is indicated by an arrow. The ends of the crack are labeled with a pair of coordinates that take the form (x,y,z). On the right face of the pier cap column, an area of spall is identified by an arrow. The extents of the area of the spall are estimated with a rectangle, the corners of which are labeled by coordinates that take the form (x,y,z).

Figure 10. Illustration. Location of Local Element Origin and Defect Coordinates on Square Pier Column – Isometric View.
3.4.9 Round pier columns: Establish the local element origin for round columns at the top of the exposed length of the column at the intersection of the circumference of the column and a tangential line parallel to the transverse direction of the cap. The local origin is defined as (0,0) for two dimensions: “z,” vertical on the column face; and “c,” around the circumference of the column (figure 11).  

This illustration shows an isometric view of a rectangular pier cap and circular column. A three-dimensional origin is located on the top column at the interface with the underside of the pier cap, on the left side of the column. The x-axis is along the circumference of the column. The z-axis is in the vertical direction downward. On the column, a crack is indicated by an arrow. The ends of the crack are labeled with a pair of coordinates that take the form (x,z).

Figure 11. Illustration. Location of Local Element Origin and Defect Coordinates on Round Pier Column – Isometric View.

3.4.10 Treat piles visible above ground the same as columns.  
3.4.11 Joints: Locate the local origin for joints at the end of the joint closest to the deck origin in the “Y” direction.  
3.4.12 Bearings: Bearings are not described via coordinates and thus do not need a local element origin.  
3.4.13 Use a temporary marker to mark typical local origins for each type of element. Take photos of each type of local origin using FLD-DC-PH-002, Photographing for Documentation Purposes, and create a photo log.  
3.5 Use sketches as needed to document locations of local origins and to 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 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 element local origins established
Text
Exact date
   mm/dd/yyyy
Green
8 Element number
Text
 
   e.g., P1 (pier 1)
Blue
9 Portion of the element where local origin is being established
Text
 
   e.g., the concrete pier cap of pier P1
Blue
10 Description of local origin
Text
 
   e.g., bottom corner of the pier cap nearest to the local origin on the deck in the “X” and “Y” directions
Yellow
11 Photo
BLOB
 
   Picture of local element origin identified on the element
Yellow
12 Sketch
BLOB
 
   Sketch of the element with local element origin and relevant axis marked
Yellow
13 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 None.  

6.

Commentary/Background

  
6.1 For the elements identified in FLD-OP-SC-002, Structure Segmentation and Element Identification System, it is most efficient for each individual element to have a local origin from which measurements to the location of defects can be made. This protocol provides guidance on locating that origin and using the local origin to measure the location of defects.  
6.2 The local origin on each individual element has the local coordinates x = 0, y = 0, and z = 0.  
6.3 If the theoretical location of the local origin is missing due to loss of section at the local origin’s point on the element, use straight edges to estimate its location for measurement to nearby defects.  
6.4 Many elements will have one or more sets of parallel surfaces to be evaluated. For example:  
6.4.1 A pier cap has top and bottom surfaces, two surfaces at opposite ends of the cap as well as the two opposite sides of the cap.  
6.4.2 A steel I-girder has the two opposing surfaces of the web as well as the bottom surface of the top flange and the top and bottom surfaces of the bottom flange.  
6.4.3 A concrete I-girder has the two opposing surfaces of the web as well as the bottom surface of the beam and the sloped faces of the beam flanges.  
6.5 For each surface of each element being evaluated, the points that describe the location of the defect will have two coordinates with variable values; the third coordinate will have a constant value that does not account for the effects of skew and/or superelevation. For example:  
6.5.1 For a defect on the end face of the square end pier cap, the y-coordinate will be either 0 for the end of the cap nearest the local origin or a value equal to the length of the pier cap for the end of the cap farthest from the local origin.  
6.5.2 For a defect on the long face of the cap, the x-coordinate will be either 0 for the face of the cap nearest the local origin or a value equal to the width of the pier cap for the face of the cap farthest from the local origin.  
6.5.3 For a defect on the top surface of the cap, the z-coordinate will always be a value equal to the depth of the pier cap; for a defect on the underside of the cap, the z-coordinate will always be 0.  
6.6 The location of a linear defect (e.g., an individual crack) on an element is documented by determining the coordinates of the beginning and ending points of the defect on the element. The relevant coordinates—x, y, and/or z—are dependent on the type of element, the surface on which the defect is located, and the type of defect being documented. For example:  
6.6.1 If the defect being documented is a crack located on the face of the web of a girder, the crack location is defined by the x and z coordinates of the beginning and end of the crack, plus a constant value for y. In this example, the orientation of the crack would be the angle between a straight line from the beginning to the end of the crack and the x-axis.  
6.6.2 If the defect being documented is impact damage on the bottom flange of a steel girder, the location of the impact damage is defined by the x-coordinates of the beginning and end of the affected length of the flange.  
6.7 The location of an area defect (such as an irregular spall) is documented by determining the coordinates of the four corners of a rectangle bordering the largest dimensions of the defect on the element.  
6.8 The location of defects on the surface of a round pier column differs from the location of defects on elements or parts of elements that have flat surfaces, such as rectangular pier columns. Unlike the rectangular column, it is not practical to project an x-axis and a y-axis on the face of the column because it is a continuous arc. Therefore, vertical measurements of defect locations are made along the z-axis, and horizontal measurements, “c,” are made on the circumference of the round column. For example:  
6.8.1 To locate a linear defect (such as a crack) on the face of a round column, measure and record the z-coordinates and the circumferential measurement, “c,” at the beginning and end of a crack.  
6.8.2 To locate an irregular defect (such as a spall) on the face of a round column, measure and record the z-coordinates and the circumferential measurement, “c,” of the four corners of a rectangle bordering the largest dimensions of the defect on the column.  

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 Element Identification System.  
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: None.  

 

 

 

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