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REPORT
This report is an archived publication and may contain dated technical, contact, and link information
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

Visual Inspection—Bearings Protocols (VIB)

FLD-DC-VIB-001, Elastomeric Bearings

FLD-DC-VIB-002, Rocker Bearings

Long-Term Bridge Performance Program Logo

Elastomeric Bearings
LTBP Protocol #: FLD-DC-VIB-001


1.

Data Collected

 
1.1 General condition of elastomeric bearings and surrounding components, including:  
1.1.1 Bulging, splitting, and/or tearing of the neoprene pad.  
1.1.2 Condition of the steel reinforcing plates (if visible) if the bearing is a laminated neoprene pad.  
1.1.3 Longitudinal/lateral displacements and rotation of the neoprene pad.  
1.1.4 Excessive strain due to growth in the lengths and widths of unlaminated (plain) neoprene pads.  
1.1.5 Connections between the neoprene pad and the sole plate and masonry plate, between the sole plate and the beam bottom flange, and between the masonry plate and the pier or abutment.  
1.1.6 Cracking, spalls, or delaminations in the abutment seat or pier cap.  
1.1.7 Condition of the anchor bolts.  

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 Wire brush or hand broom.  
2.1.4 Tape measure.  
2.1.5 6-ft folding rule.  
2.1.6 Crack gage.  
2.1.7 Slide caliper.  
2.1.8 Digital level.  
2.1.9 Plumb bob.  
2.1.10 Laser measuring device (optional).  
2.1.11 Hand compass or other angle-measuring device.  
2.1.12 Thermometer.  
2.1.13 Mirror.  
2.1.14 Temporary marker.  
2.1.15 Digital camera.  
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) to identify the bearings being evaluated.  
3.2 Measuring, recording, and evaluating characteristics of bearings:  
3.2.1 Record the ambient temperatures above the deck and at the location of the bearing at the time of visual inspection.  
3.2.2 Record if the bearing is a fixed or a moveable bearing. Examine the bearing. If it is a moveable bearing, does it still allow movement?  
3.2.3 Record if the bearing is still in its proper alignment.  
3.3 Measuring, recording, and evaluating characteristics of neoprene:  
3.3.1 Use a wire brush or hand broom to clean the bearing area to allow close visual inspection.  
3.3.2 Record if the elastomeric bearing is a plain neoprene pad or a laminated neoprene pad.  
3.3.3 Measure bearing thickness, length and width, and any longitudinal and lateral displacements or rotations.  
3.3.4 Examine the neoprene pad (plain or laminated) for defects on contact surfaces, bulging and split or torn surfaces, and excessive longitudinal and/or lateral displacements and rotations.  
3.3.4.1 If there are splits or tears in the neoprene, check for steel shim exposure and condition, if exposed.  
3.3.4.2 If there are splits in the neoprene, measure the length, width, and depth of each split.  
3.3.4.3 If there is bulging, measure the amount of bulge using the slide caliper.  
3.3.4.4 To determine rotation, measure the displacement of the top of the bearing face versus the bottom of the bearing face.  
3.3.4.5 Use a mirror, if necessary, to examine the vertical surface of the bearing closest to the abutment backwall.  
3.3.5 Is there a restraining device to keep the neoprene pad from moving horizontally from its original position? If so, record it and take a photograph of a typical restraining device.  
3.4 Measuring, recording, and evaluating characteristics of the sole plate:  
3.4.1 Examine the connection of the sole plate to the girder. Record any loss of bond and connection between the sole plate and the girder.  
3.4.2 Examine the sole plate, and record any cracks, corrosion, and/or section loss of the sole plate.  
3.5 Measuring, recording, and evaluating characteristics of the masonry plate:  
3.5.1 Examine the connection of the masonry plate to the bearing device and the masonry plate to the abutment or pier. Record any loss of connection.  
3.5.2 Examine the masonry plate, and record any cracks, corrosion, and/or loss of section.  
3.6 Measuring, recording, and evaluating characteristics of the anchor bolt:  
3.6.1 Examine the anchor bolts connecting the masonry plate to the pier or abutment. Record the diameter of the bolts.  
3.6.2 Record any missing bolts, nuts, or washers.  
3.6.3 Record any rust or corrosion of the bolts.  
3.6.4 Examine the concrete around the anchor bolt and record if any part of the main body (shank) of the anchor bolt is exposed.  
3.7 Measuring, recording, and evaluating characteristics of concrete surface (under and next to the bearing):  
3.7.1 Check the condition of the concrete surfaces under and next to the bearing and record any defects.  
3.7.2 Check for spalls and/or cracks in the pier or abutment top surface.  
3.8 Documenting defects:  
3.8.1 Take photographs of defects using FLD-DC-PH-002, Photographing for Documentation Purposes, and create a photo log.  
3.8.2 Use sketches to document spalls and cracking and supplement the photographs.  
3.9 Storing data, documents, and images:  
3.9.1 FLD-DS-LS-001, Data, Document, and Image Storage—Local, for local storage.  
3.9.2 FLD-DS-RS-001, Data, Document, and Image Storage—Remote, for remote storage.  
3.10 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
8 Ambient temperature above deck
Number
1
°F
 
Green
9 Bearing number
Text
 
 
Evaluate and record data for each individual bearing
Blue
10 Ambient temperature at bearing location
Number
1
°F
 
Yellow
11 Is the bearing fixed or moveable?
Predefined list
 
 
Fixed or Movable
Yellow
12 If it is a moveable bearing, does it still allow movement?
Predefined list
 
 
Yes, No, or Not Applicable
Yellow
13 Is the bearing still in its proper alignment?
Predefined list
 
 
Yes or No
Yellow
14 Is bearing plain neoprene pad or a laminated neoprene pad?
Predefined list
 
 
Plain or laminated
Yellow
15 Neoprene condition
Text
 
 
Indicate no visible defects or document the presence of splits or tears, bulging, steel shim (plate) exposure, corroded shims (steel plates), presence of oxidation, and/or other defect (specify under comments)
Yellow
16 Sole plate connection to girder—surface bond condition
Text
 
 
Indicate no visible defects or document the presence of bond or no bond, movement of sole plate, and/or other defect (specify under comments)
Yellow
17 Sole plate condition
Text
 
 
Record any corrosion or section loss
Yellow
18 Masonry plate connection to the abutment or pier
Text
 
 
Record any loss of connection
Yellow
19 Masonry plate condition
Text
 
 
Record any corrosion or section loss
Yellow
20 Diameter of anchor bolts
Number
0.125
in.
 
Yellow
21 Condition of the anchor bolts
Text
 
 
Record any missing bolts, nuts, or washers; any rust or corrosion of the bolts; if the anchor bolt is partially exposed
Yellow
22 Condition of the concrete under and next to the bearing
Text
 
 
Indicate no visible defects or document the presence of shear cracks, spalling, on abutment seat or pier cap, and/or other defect (specify under comments)
Yellow
23 Rotation of neoprene pad
Number
1
Degrees
 
Yellow
24 Longitudinal displacement of neoprene pad
Number
0.125
in.
 
Yellow
25 Lateral displacement of neoprene pad
Number
0.125
in.
 
Yellow
26 Length of neoprene pad
Number
0.125
in.
 
Yellow
27 Width of neoprene pad
Number
0.125
in.
 
Yellow
28 Height (thickness) measurement of pad
Number
0.125
in.
 
Yellow
29 Defect photos
BLOB
 
 
 
Yellow
30 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 evaluating the condition of elastomeric bearings and for collecting data that help determine if the bearing is functioning as intended.  
6.2 Elastomeric bearings are either reinforced (laminated) or nonreinforced (unlaminated). Steel plates (shims) are used as the reinforcing material in the rubber (neoprene) pad.  
6.3 Sole plates are attached to the underside of bridge girders and transfer the force from the bridge girder to the bearing device.  
6.4 The bearing device sits on top of a masonry plate. Masonry plates are attached to piers and abutments and transfer the force from the bearing device to the pier or abutment.  
6.5 Anchor bolts are used to attach the masonry plate to the pier or abutment. The body of an anchor bolt (shank) should not be visible. Only the head of the anchor bolt, a nut, and a washer should be visible. If the body (shank) of the anchor bolt is visible, then the anchor bolts are said to be exposed.  

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-DC-PH-002, Photographing for Documentation Purposes.  
7.1.5 FLD-DS-LS-001, Data, Document, and Image Storage—Local.  
7.1.6 FLD-DS-RS-001, Data, Document, and Image Storage—Remote.  
7.2 External:  
7.2.1 FHWA. (2012). Bridge Inspector’s Reference Manual – Report No. FHWA-NHI-12-053, Federal Highway Administration, Washington, DC.  

 

 

 

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