ASTM D5977-23
(Specification)Standard Specification for High Load Rotational Spherical Bearings for Bridges and Structures
Standard Specification for High Load Rotational Spherical Bearings for Bridges and Structures
ABSTRACT
This specification covers bridge bearings that consist of a spherical rotational element, where a stainless steel convex surface slides against a concave carbon steel plate covered with woven or sheet polytetrafluoroethylene (PTFE). The function of the bearing is to transfer loads and to accommodate any relative movement, including rotation between a bridge superstructure and its supporting structure, or both. The requirements of spherical bearings with a standard horizontal load (a maximum of 10 % of vertical) are discussed. The bearings are furnished in three types: fixed spherical bearing which is for rotation only, unidirectional sliding spherical bearing which is for rotation plus movement in one direction, and multi-directional sliding spherical bearing which is for rotation plus movement in all directions. The materials to be used in producing the bearings include: steel, stainless steel (flat sliding surface and convex surface), woven fabric polytetrafluoroethylene, and sheet polytetrafluoroethylene. The following different test methods shall be performed: proof load and rotation tests for fixed and expansion bearings, coefficient of friction test for expansion bearings only, PTFE (woven or sheet) bond test for expansion bearings only, and physical property test of both PTFEs for fixed and expansion bearings.
SCOPE
1.1 This specification covers bridge bearings that consist of a spherical rotational element, where a stainless steel convex surface slides against a concave carbon steel plate covered with woven or sheet polytetrafluoroethylene (PTFE). The function of the bearing is to transfer loads and to accommodate any relative movement, including rotation between a bridge superstructure and its supporting structure, or both.
1.2 This specification covers the requirements of spherical bearings with a standard horizontal load (a maximum of 10 % of vertical).
1.3 The requirements stated in this specification are the minima necessary for the manufacture of quality bearing devices. It may be necessary to increase these minimum values due to other design conditions.
1.4 Units—The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical conversions to SI units that are provided for information only and are not considered standard.
1.5 The text of this standard references notes and footnotes which provide explanatory material. These notes and footnotes (excluding those in tables and figures) shall not be considered as requirements of the standard.
1.6 The following safety hazards caveat pertains only to the test method portion, Section 7, of this specification: This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.
1.7 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
General Information
- Status
- Published
- Publication Date
- 30-Apr-2023
- Technical Committee
- D04 - Road and Paving Materials
- Drafting Committee
- D04.32 - Bridges and Structures
Relations
- Effective Date
- 01-Nov-2023
- Effective Date
- 01-Jul-2019
- Effective Date
- 01-Nov-2017
- Effective Date
- 01-Sep-2017
- Effective Date
- 01-Sep-2017
- Effective Date
- 01-Dec-2016
- Effective Date
- 01-Dec-2016
- Effective Date
- 01-May-2016
- Effective Date
- 01-May-2016
- Effective Date
- 15-Feb-2016
- Effective Date
- 01-Nov-2015
- Effective Date
- 01-Jul-2015
- Effective Date
- 01-Mar-2015
- Effective Date
- 01-Jan-2015
- Effective Date
- 01-May-2014
Overview
ASTM D5977-23 is the Standard Specification for High Load Rotational Spherical Bearings for Bridges and Structures. Published by ASTM International, this standard sets out the minimum requirements for the design, materials, manufacturing, and testing of spherical bearings used in bridges and similar structures. The primary purpose of these spherical bridge bearings is to efficiently transfer loads from bridge superstructures to their supporting structures while accommodating relative movements such as rotation and translation.
Spherical bearings under this standard feature a stainless steel convex surface sliding over a concave carbon steel plate, with woven or sheet polytetrafluoroethylene (PTFE) acting as a low-friction interface. The standard provides guidance for horizontal load tolerances, material selection, bearing types, testing, and acceptance criteria, supporting the construction and maintenance of safe, durable, and efficient bridge bearings.
Key Topics
Bearing Types:
- Fixed Spherical Bearing: Permits rotational movement only.
- Unidirectional Sliding Spherical Bearing: Allows rotation and movement in one direction.
- Multi-directional Sliding Spherical Bearing: Accommodates rotation and movement in all directions.
Material Requirements:
- Structural steel for primary plates, conforming to standards such as ASTM A36, A572, A588, or A709.
- Stainless steel (Type 304, flat and convex surfaces) as per ASTM A240, for sliding and rotational elements.
- Woven fabric or sheet PTFE, ensuring low friction and high durability.
- Mechanical and epoxy bonding systems for PTFE attachment to substrates.
Load Capacities:
- Spherical bearings must handle vertical loads with the standard horizontal load limited to a maximum of 10% of the vertical load.
Testing and Quality Control:
- Rigorous proof load, rotation, friction coefficient, and PTFE bond tests.
- Verification of material physical properties.
- Thorough inspection against criteria for deformation, separation, and functional integrity.
Product Marking:
- Bearings must be clearly labeled with manufacturer, identification, and placement details for proper installation and traceability.
Applications
ASTM D5977-23 is essential for the following applications:
Bridge Engineering:
Spherical bearings designed per this standard are widely used in highway bridges, railway bridges, and other transportation-related structures. They ensure safe transfer of structural loads and accommodate movements caused by traffic, temperature variation, wind, and seismic events.Civil Infrastructure:
Beyond bridges, these bearings support movement and load transfer in large civil structures such as stadiums, high-rise buildings with structural articulation, and infrastructure requiring high load rotational or translational capability.Rehabilitation and Upgrades:
The standard’s requirements guide the selection and upgrade of bearings in maintenance, refurbishment, and seismic retrofitting projects, ensuring compliance with current best practices for safety and durability.
Related Standards
Several important ASTM, AASHTO, and AWS standards are cited and relate closely to ASTM D5977-23, including:
- ASTM A36/A36M: Carbon Structural Steel Specification
- ASTM A240/A240M: Chromium and Chromium-Nickel Stainless Steel Plate, Sheet, and Strip
- ASTM D638: Test Method for Tensile Properties of Plastics
- ASTM D1777: Test Method for Thickness of Textile Materials
- AASHTO Standard Specifications for Highway Bridges
- AWS D1.5: ANSI/AASHTO/AWS Bridge Welding Code
Practical Value
By following ASTM D5977-23, engineers, manufacturers, and infrastructure owners can ensure:
- Enhanced durability and safety for bridge bearings, even under high loads and demanding environmental conditions.
- Consistent material and manufacturing quality through referenced specifications and standardized testing protocols.
- Effective movement accommodation and long-term performance, reducing maintenance and lifecycle costs.
- Clear guidelines for marking and traceability, aiding quality control and future maintenance.
Keywords: spherical bridge bearings, high load rotational bearings, PTFE bearings, bridge bearing standards, ASTM D5977, bearing devices, stainless steel sliding surface, civil infrastructure bearings, bridge structures.
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Frequently Asked Questions
ASTM D5977-23 is a technical specification published by ASTM International. Its full title is "Standard Specification for High Load Rotational Spherical Bearings for Bridges and Structures". This standard covers: ABSTRACT This specification covers bridge bearings that consist of a spherical rotational element, where a stainless steel convex surface slides against a concave carbon steel plate covered with woven or sheet polytetrafluoroethylene (PTFE). The function of the bearing is to transfer loads and to accommodate any relative movement, including rotation between a bridge superstructure and its supporting structure, or both. The requirements of spherical bearings with a standard horizontal load (a maximum of 10 % of vertical) are discussed. The bearings are furnished in three types: fixed spherical bearing which is for rotation only, unidirectional sliding spherical bearing which is for rotation plus movement in one direction, and multi-directional sliding spherical bearing which is for rotation plus movement in all directions. The materials to be used in producing the bearings include: steel, stainless steel (flat sliding surface and convex surface), woven fabric polytetrafluoroethylene, and sheet polytetrafluoroethylene. The following different test methods shall be performed: proof load and rotation tests for fixed and expansion bearings, coefficient of friction test for expansion bearings only, PTFE (woven or sheet) bond test for expansion bearings only, and physical property test of both PTFEs for fixed and expansion bearings. SCOPE 1.1 This specification covers bridge bearings that consist of a spherical rotational element, where a stainless steel convex surface slides against a concave carbon steel plate covered with woven or sheet polytetrafluoroethylene (PTFE). The function of the bearing is to transfer loads and to accommodate any relative movement, including rotation between a bridge superstructure and its supporting structure, or both. 1.2 This specification covers the requirements of spherical bearings with a standard horizontal load (a maximum of 10 % of vertical). 1.3 The requirements stated in this specification are the minima necessary for the manufacture of quality bearing devices. It may be necessary to increase these minimum values due to other design conditions. 1.4 Units—The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical conversions to SI units that are provided for information only and are not considered standard. 1.5 The text of this standard references notes and footnotes which provide explanatory material. These notes and footnotes (excluding those in tables and figures) shall not be considered as requirements of the standard. 1.6 The following safety hazards caveat pertains only to the test method portion, Section 7, of this specification: This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use. 1.7 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
ABSTRACT This specification covers bridge bearings that consist of a spherical rotational element, where a stainless steel convex surface slides against a concave carbon steel plate covered with woven or sheet polytetrafluoroethylene (PTFE). The function of the bearing is to transfer loads and to accommodate any relative movement, including rotation between a bridge superstructure and its supporting structure, or both. The requirements of spherical bearings with a standard horizontal load (a maximum of 10 % of vertical) are discussed. The bearings are furnished in three types: fixed spherical bearing which is for rotation only, unidirectional sliding spherical bearing which is for rotation plus movement in one direction, and multi-directional sliding spherical bearing which is for rotation plus movement in all directions. The materials to be used in producing the bearings include: steel, stainless steel (flat sliding surface and convex surface), woven fabric polytetrafluoroethylene, and sheet polytetrafluoroethylene. The following different test methods shall be performed: proof load and rotation tests for fixed and expansion bearings, coefficient of friction test for expansion bearings only, PTFE (woven or sheet) bond test for expansion bearings only, and physical property test of both PTFEs for fixed and expansion bearings. SCOPE 1.1 This specification covers bridge bearings that consist of a spherical rotational element, where a stainless steel convex surface slides against a concave carbon steel plate covered with woven or sheet polytetrafluoroethylene (PTFE). The function of the bearing is to transfer loads and to accommodate any relative movement, including rotation between a bridge superstructure and its supporting structure, or both. 1.2 This specification covers the requirements of spherical bearings with a standard horizontal load (a maximum of 10 % of vertical). 1.3 The requirements stated in this specification are the minima necessary for the manufacture of quality bearing devices. It may be necessary to increase these minimum values due to other design conditions. 1.4 Units—The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical conversions to SI units that are provided for information only and are not considered standard. 1.5 The text of this standard references notes and footnotes which provide explanatory material. These notes and footnotes (excluding those in tables and figures) shall not be considered as requirements of the standard. 1.6 The following safety hazards caveat pertains only to the test method portion, Section 7, of this specification: This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use. 1.7 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
ASTM D5977-23 is classified under the following ICS (International Classification for Standards) categories: 93.040 - Bridge construction. The ICS classification helps identify the subject area and facilitates finding related standards.
ASTM D5977-23 has the following relationships with other standards: It is inter standard links to ASTM A240/A240M-23a, ASTM D1777-96(2019), ASTM A240/A240M-17, ASTM A709/A709M-17e1, ASTM A709/A709M-17, ASTM A304-16, ASTM A240/A240M-16a, ASTM A709/A709M-16a, ASTM A240/A240M-16, ASTM A709/A709M-16, ASTM A240/A240M-15b, ASTM D1777-96(2015), ASTM A240/A240M-15a, ASTM A240/A240M-15, ASTM A240/A240M-14. Understanding these relationships helps ensure you are using the most current and applicable version of the standard.
ASTM D5977-23 is available in PDF format for immediate download after purchase. The document can be added to your cart and obtained through the secure checkout process. Digital delivery ensures instant access to the complete standard document.
Standards Content (Sample)
This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: D5977 − 23
Standard Specification for
High Load Rotational Spherical Bearings for Bridges and
Structures
This standard is issued under the fixed designation D5977; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope mendations issued by the World Trade Organization Technical
Barriers to Trade (TBT) Committee.
1.1 This specification covers bridge bearings that consist of
a spherical rotational element, where a stainless steel convex
2. Referenced Documents
surface slides against a concave carbon steel plate covered with
2.1 ASTM Standards:
woven or sheet polytetrafluoroethylene (PTFE). The function
A36/A36M Specification for Carbon Structural Steel
of the bearing is to transfer loads and to accommodate any
A167 Specification for Stainless and Heat-Resisting
relative movement, including rotation between a bridge super-
Chromium-Nickel Steel Plate, Sheet, and Strip (With-
structure and its supporting structure, or both.
drawn 2014)
1.2 This specification covers the requirements of spherical
A240/A240M Specification for Chromium and Chromium-
bearings with a standard horizontal load (a maximum of 10 %
Nickel Stainless Steel Plate, Sheet, and Strip for Pressure
of vertical).
Vessels and for General Applications
A304 Specification for Carbon and Alloy Steel Bars Subject
1.3 The requirements stated in this specification are the
to End-Quench Hardenability Requirements
minima necessary for the manufacture of quality bearing
A572/A572M Specification for High-Strength Low-Alloy
devices. It may be necessary to increase these minimum values
Columbium-Vanadium Structural Steel
due to other design conditions.
A588/A588M Specification for High-Strength Low-Alloy
1.4 Units—The values stated in inch-pound units are to be
Structural Steel, up to 50 ksi [345 MPa] Minimum Yield
regarded as standard. The values given in parentheses are
Point, with Atmospheric Corrosion Resistance
mathematical conversions to SI units that are provided for
A709/A709M Specification for Structural Steel for Bridges
information only and are not considered standard.
D638 Test Method for Tensile Properties of Plastics
1.5 The text of this standard references notes and footnotes
D792 Test Methods for Density and Specific Gravity (Rela-
which provide explanatory material. These notes and footnotes
tive Density) of Plastics by Displacement
(excluding those in tables and figures) shall not be considered
D1457 Specification for Polytetrafluoroethylene (PTFE)
as requirements of the standard.
Molding and Extrusion Materials (Withdrawn 1996)
D1777 Test Method for Thickness of Textile Materials
1.6 The following safety hazards caveat pertains only to the
test method portion, Section 7, of this specification: This D2256/D2256M Test Method for Tensile Properties of Yarns
by the Single-Strand Method
standard does not purport to address all of the safety concerns,
if any, associated with its use. It is the responsibility of the user 2.2 AASHTO Standard:
AASHTO Standard Specifications for Highway Bridges
of this standard to establish appropriate safety, health, and
environmental practices and determine the applicability of 2.3 AWS Standards:
C2.2-67 Metalizing with Aluminum and Zinc for Protection
regulatory limitations prior to use.
1.7 This international standard was developed in accor- of Iron and Steel
dance with internationally recognized principles on standard-
ization established in the Decision on Principles for the
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Development of International Standards, Guides and Recom-
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website.
The last approved version of this historical standard is referenced on
This specification is under the jurisdiction of ASTM Committee D04 on Road www.astm.org.
and Paving Materials and is the direct responsibility of Subcommittee D04.32 on Available from American Association of State Highway and Transportation
Bridges and Structures. Officials (AASHTO), 444 N. Capitol St., NW, Suite 249, Washington, DC 20001,
Current edition approved May 1, 2023. Published May 2023. Originally http://www.transportation.org.
approved in 1996. Last previous edition approved in 2015 as D5977 – 15. DOI: Available from American Welding Society (AWS), 550 NW LeJeune Rd.,
10.1520/D5977-23. Miami, FL 33126, http://www.aws.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D5977 − 23
TABLE 1 Physical Property Requirements for Woven PTFE
D1.5 ANSI/AASHTO/AWS Bridge Welding Code
Physical Properties Test Method Requirement
3. Classification
Ultimate tensile strength, min, psi (MPa) D2256/D2256M 24 000 (165.4)
Ultimate elongation, min, % D2256/D2256M >10 % #35 %
3.1 The bearings are furnished in three types, as follows:
3.1.1 Fixed Spherical Bearing—Rotation only.
3.1.2 Unidirectional Sliding Spherical Bearing—Rotation
plus movement in one direction.
ments of Specification D1457. The PTFE shall be resistant to
3.1.3 Multi-Directional Sliding Spherical Bearing—
acids, alkalis, petroleum products, and nonabsorbtion of water.
Rotation plus movement in all directions.
It shall be stable for temperatures up to 500 °F (260 °C) and
shall be nonflammable. When used in PTFE surfaces used for
4. Material Specifications
guide bars only, filler material shall be composed of milled
4.1 Steel—The steel used for all major plates shall be
glass fibers or carbon.
structural steel conforming to Specification A36/A36M, A588/
4.4.1 The thickness of the sheet PTFE shall be a minimum
A588M, A572/A572M, or A709/A709M, as required. All
of ⁄8 in. (3.17 mm) and shall be recessed at least one half of its
exposed surfaces shall be zinc metalized according to AWS
thickness.
C2.2-67 (with no chipping), having a minimum thickness of
4.4.2 The PTFE for the principal slide surface and for guide
6 mil (0.152 mm) or treated with other project-approved
bars shall conform to the physical requirements listed in Table
coating systems such as coal tar or inorganic zinc paint. The
2.
dry film thickness (DFT) of the approved paint system must be
specified by the owner.
A
TABLE 2 Physical Property Requirements for Sheet PTFE
4.2 Stainless Steel:
Physical Properties Test Method Requirement
4.2.1 Flat Sliding Surface—The sheet stainless steel used as
Ultimate tensile strength, min, psi (MPa) D638 2800 (19.3)
the mating sliding surface to the woven fabric PTFE or sheet
Ultimate elongation, min, % D638 200
PTFE in the sliding spherical bearings shall conform to
Specific gravity, min D792 2.12
Specification A167 or A240/A240M, type 304, 20 μin. A
15 % glass-filled PTFE may be used for guide bar surfaces (Specification
(0.5 μm) rms finish. D1457).
4.2.2 Convex Surface—The solid stainless steel plate or
sheet stainless steel used as the mating rotational convex
surface to the woven fabric PTFE or sheet PTFE shall conform
5. Design Requirements
to Specification A167 or A240/A240M, type 304. The surface
NOTE 1—To Designer: The bearing details shall be designed in
shall be machined to a surface finish of 20 μin. (0.5 μm) rms or
accordance with the requirements of the current edition with interims of
less.
the AASHTO Standard Specifications for Highway Bridges or other
governing design procedures.
4.3 Woven Fabric Polytetrafluoroethylene (PTFE)—The
5.1 Rotational Elements:
woven fabric PTFE shall be made from virgin PTFE oriented
multifilament fibers with or without a high-strength backing. 5.1.1 The spherical radius shall be determined such that the
resulting geometry of the bearing is capable of withstanding
4.3.1 The thickness of the woven fabric PTFE in the free
state shall be a minimum of ⁄32 in. (2.38 mm) when measured the greatest ratio of the horizontal load to vertical load under all
loading conditions to prevent the unseating (separation at the
in accordance with Test Method D1777.
4.3.2 The thickness of the bonded woven fabric PTFE under edges) of the convex/concave elements.
5.1.2 Unseating of the curved spherical surfaces relative to
the application of vertical load (excluding any backing mate-
rial) shall be a minimum of the following: each other shall be prevented by transferring horizontal forces
through specifically designed restraints or by control of the
(1) ⁄16 in. (1.59 mm) from 0 psi (0 N/mm ) to 3500 psi
(24.1 N/mm ). spherical radius.
5.1.3 Acceptable spherical radius control shall be given
(2) ⁄64 in. (1.19 mm) from 3501 psi (24.1 N/mm ) to 4500
psi (31.0 N/mm ). when the configuration of the woven fabric PTFE concave
radius follows the following design:
4.3.3 The woven fabric PTFE shall be mechanically inter-
locked and epoxy-bonded to the substrate using a system that
ratio # tan α (1)
prevents migration of the epoxy through the fabric. The use of
where:
a mechanical interlock system along with the epoxy increases
the bond strength, providing a redundancy for the prevention of ratio = worst-case ratio of horizontal to vertical loads.
migration of the PTFE material. Any edges, other than the
d/2
α 5 arcsin 2 design rotation (2)
selvedge (woven edge), shall be oversewn so that no cut fabric S S DD ~ !
Rmax
edges are exposed.
where:
4.3.4 The individual PTFE filaments used in making the
d = projected diameter of the woven fabric
woven PTFE fabric shall conform to the physical requirements
of Table 1. PTFE,
design rotation = design rotation of the bearing (in degrees),
4.4 Sheet Polytetrafluoroethylene (PTFE)—The sheet PTFE
and
shall be virgin material (not reprocessed) meeting the require-
D5977 − 23
capable of resisting the frictional force set up in the bearing.
Rmax = maximum allowable radius to prevent up-
Welding must be in accordance with ANSI/AASHTO/AWS
lift within the bearing during the worst
D1.5.
horizontal to vertical load case.
5.2.3 The backing plate shall extend beyond the edge of the
5.1.4 Calculations showing determination of the radius shall
stainless steel sheet to accommodate the weld; also, the weld
be submitted for approval.
must not protrude above the stainless steel sheet. TIG welding
5.1.5 The radius of the convex plate shall be less than the
of the stainless steel sheet is highly recommended to achieve
radius calculated for the woven fabric PTFE (concave plate) by
this connection.
a value equal to the thickness of the PTFE.
5.2.4 The flat horizontal stainless steel sliding surface shall
5.1.6 The concave surface shall face down whenever the
cover the PTFE surface completely in all operations, plus one
resulting center of rotation is not detrimental to the system
additional inch (25.4 mm) in all directions of movement. For a
geometry. See Fig. 1.
guided bearing with which there is no transverse movement,
5.1.7 The minimum thickness at the center of the concave
this requirement does not apply in the transverse direction.
spherical element shall be ⁄4 in. (19 mm).
5.1.8 The minimum thickness at the edge of the convex 5.3 Woven Fabric PTFE Concave or Sliding Surfaces, or
spherical element shall be ⁄2 in. (12.7 mm).
Both:
5.1.9 Vertical and horizontal clearance betwee
...
This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: D5977 − 15 D5977 − 23
Standard Specification for
High Load Rotational Spherical Bearings for Bridges and
Structures
This standard is issued under the fixed designation D5977; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope
1.1 This specification covers bridge bearings that consist of a spherical rotational element, where a stainless steel convex surface
slides against a concave carbon steel plate covered with woven or sheet polytetrafluoroethylene (PTFE). The function of the
bearing is to transfer loads and to accommodate any relative movement, including rotation between a bridge superstructure and
its supporting structure, or both.
1.2 This specification covers the requirements of spherical bearings with a standard horizontal load (a maximum of 10 % of
vertical).
1.3 The requirements stated in this specification are the minima necessary for the manufacture of quality bearing devices. It may
be necessary to increase these minimum values due to other design conditions.
1.4 Units—The values stated in inch-pound units are to be regarded as the standard. The values given in parentheses are for
information only.mathematical conversions to SI units that are provided for information only and are not considered standard.
1.5 The text of this standard references notes and footnotes which provide explanatory material. These notes and footnotes
(excluding those in tables and figures) shall not be considered as requirements of the standard.
1.6 The following safety hazards caveat pertains only to the test method portion, Section 7, of this specification: This standard
does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this
standard to establish appropriate safety and healthsafety, health, and environmental practices and determine the applicability of
regulatory limitations prior to use.
1.7 This international standard was developed in accordance with internationally recognized principles on standardization
established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued
by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
2. Referenced Documents
2.1 ASTM Standards:
A36/A36M Specification for Carbon Structural Steel
This specification is under the jurisdiction of ASTM Committee D04 on Road and Paving Materials and is the direct responsibility of Subcommittee D04.32 on Bridges
and Structures.
Current edition approved June 1, 2015May 1, 2023. Published July 2015May 2023. Originally approved in 1996. Last previous edition approved in 20122015 as
D5977 – 03 (2012).D5977 – 15. DOI: 10.1520/D5977-15.10.1520/D5977-23.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D5977 − 23
A167 Specification for Stainless and Heat-Resisting Chromium-Nickel Steel Plate, Sheet, and Strip (Withdrawn 2014)
A240/A240M Specification for Chromium and Chromium-Nickel Stainless Steel Plate, Sheet, and Strip for Pressure Vessels and
for General Applications
A304 Specification for Carbon and Alloy Steel Bars Subject to End-Quench Hardenability Requirements
A572/A572M Specification for High-Strength Low-Alloy Columbium-Vanadium Structural Steel
A588/A588M Specification for High-Strength Low-Alloy Structural Steel, up to 50 ksi [345 MPa] Minimum Yield Point, with
Atmospheric Corrosion Resistance
A709/A709M Specification for Structural Steel for Bridges
D638 Test Method for Tensile Properties of Plastics
D792 Test Methods for Density and Specific Gravity (Relative Density) of Plastics by Displacement
D1457 Specification for Polytetrafluoroethylene (PTFE) Molding and Extrusion Materials (Withdrawn 1996)
D1777 Test Method for Thickness of Textile Materials
D2256D2256/D2256M Test Method for Tensile Properties of Yarns by the Single-Strand Method
2.2 AASHTO Standard:
AASHTO Standard Specifications for Highway Bridges
2.3 AWS Standards:
C.2.2-67C2.2-67 Metalizing with Aluminum and Zinc for Protection of Iron and Steel
D.1.5D1.5 ANSI/AASHTO/AWS Bridge Welding Code
3. Classification
3.1 The bearings are furnished in three types, as follows:
3.1.1 Fixed Spherical Bearing—Rotation only.
3.1.2 Uni-DirectionalUnidirectional Sliding Spherical Bearing—Rotation plus movement in one direction.
3.1.3 Multi-Directional Sliding Spherical Bearing—Rotation plus movement in all directions.
4. Material Specifications
4.1 Steel—The steel used for all major plates shall be structural steel conforming to SpecificationsSpecification A36/A36M,
A588/A588M, A572/A572M, or A709/A709M, as required. All exposed surfaces shall be zinc metalized according to AWS
C.2.2-67C2.2-67 (with no chipping), having a minimum thickness of 6 mil 6 mil (0.152 mm) or treated with other project-approved
coating systems such as coal tar or inorganic zinc paint. The dry film thickness (DFT) of the approved paint system must be
specified by the owner.
4.2 Stainless Steel:
4.2.1 Flat Sliding Surface—The sheet stainless steel used as the mating sliding surface to the woven fabric PTFE or sheet PTFE
in the sliding spherical bearings shall conform to Specification A167 or A240/A240M, type 304, 20-μin. (0.5-μm) 20 μin. (0.5 μm)
rms finish.
4.2.2 Convex Surface—The solid stainless steel plate or sheet stainless steel used as the mating rotational convex surface to the
woven fabric PTFE or sheet PTFE shall conform to Specification A167 or A240/A240M, type 304. The surface shall be machined
to a surface finish of 20-μin. (0.5-μm) 20 μin. (0.5 μm) rms or less.
4.3 Woven Fabric Polytetrafluoroethylene (PTFE)—The woven fabric PTFE shall be made from virgin PTFE oriented
multifilament fibers with or without a high-strength backing.
4.3.1 The thickness of the woven fabric PTFE in the free state shall be a minimum of ⁄32 in. (2.38 mm) when measured in
accordance with Test Method D1777.
The last approved version of this historical standard is referenced on www.astm.org.
Available from American Association of State Highway and Transportation Officials (AASHTO), 444 N. Capitol St., NW, Suite 249, Washington, DC 20001,
http://www.transportation.org.
Available from American Welding Society (AWS), 550 NW LeJeune Rd., Miami, FL 33126, http://www.aws.org.
D5977 − 23
4.3.2 The thickness of the bonded woven fabric PTFE under the application of vertical load (excluding any backing material) shall
be a minimum of the following:
2 2
(1) ⁄16 in. (1.59 mm) from 0 psi (0 N/mm ) to 3500 psi (24.1 N/mm ).
2 2
(2) ⁄64 in. (1.19 mm) from 3501 psi (24.1 N/mm ) to 4500 psi (31.0 N/mm ).
4.3.3 The woven fabric PTFE shall be mechanically interlocked and epoxy-bonded to the substrate using a system that prevents
migration of the epoxy through the fabric. The use of a mechanical interlock system along with the epoxy increases the bond
strength, providing a redundancy for the prevention of migration of the PTFE material. Any edges, other than the selvedge (woven
edge), shall be oversewn so that no cut fabric edges are exposed.
4.3.4 The individual PTFE filaments used in making the woven PTFE fabric shall conform to the physical requirements of Table
1.
4.4 Sheet Polytetrafluoroethylene (PTFE)—The sheet PTFE shall be virgin material (not reprocessed) meeting the requirements
of Specification D1457. The PTFE shall be resistant to acids, alkalis, petroleum products, and nonabsorbtion of water. It shall be
stable for temperatures up to 500°F (260°C)500 °F (260 °C) and shall be nonflammable. When used in PTFE surfaces used for
guide bars only, filler material shall be composed of milled glass fibers or carbon.
4.4.1 The thickness of the sheet PTFE shall be a minimum of ⁄8 in. (3.17 mm) and shall be recessed at least one-half one half
of its thickness.
4.4.2 The PTFE for the principal slide surface and for guide bars shall conform to the physical requirements listed in Table 2.
A
TABLE 2 Physical Property Requirements for Sheet PTFE
Physical Properties Test Method Requirement
Ultimate tensile strength, min, psi (MPa) D638 2800 (19.3)
Ultimate elongation, min, % D638 200
Specific gravity, min D792 2.12
A
15 % glass-filled PTFE may be used for guide bar surfaces (Specification
D1457).
5. Design Requirements
NOTE 1—To Designer: The bearing details shall be designed in accordance with the requirements of the current edition with interims of the AASHTO
Standard Specifications for Highway Bridges or other governing design procedures.
5.1 Rotational Elements:
5.1.1 The spherical radius shall be determined such that the resulting geometry of the bearing is capable of withstanding the
greatest ratio of the horizontal load to vertical load under all loading conditions to prevent the unseating (separation at the edges)
of the convex/concave elements.
5.1.2 Unseating of the curved spherical surfaces relative to each other shall be prevented by transferring horizontal forces through
specifically designed restraints or by control of the spherical radius.
5.1.3 Acceptable spherical radius control shall be given when the configuration of the woven fabric PTFE concave radius follows
the following design:
TABLE 1 Physical Property Requirements for Woven PTFE
Physical Properties Test Method Requirement
Ultimate tensile strength, min, psi (MPa) D2256 24 000 (165.4)
Ultimate elongation, min, % D2256 >10 % # 35 %
TABLE 1 Physical Property Requirements for Woven PTFE
Physical Properties Test Method Requirement
Ultimate tensile strength, min, psi (MPa) D2256/D2256M 24 000 (165.4)
Ultimate elongation, min, % D2256/D2256M >10 % #35 %
D5977 − 23
ratio # tan α (1)
where:
ratio = worst case ratio of horizontal to vertical loads.
ratio = worst-case ratio of horizontal to vertical loads.
d/2
α5 arcsin 2 design rotation (2)
S S DD ~ !
Rmax
where:
d = projected diameter of the woven fabric PTFE,
design rotation = design rotation of the bearing (in degrees), and
Rmax = maximum allowable radius to prevent uplift within the bearing during the worst horizontal to vertical load
case.
5.1.4 Calculations showing determination of the radius shall be submitted for approval.
5.1.5 The radius of the convex plate shall be less than the radius calculated for the woven fabric PTFE (concave plate) by a value
equal to the thickness of the PTFE.
5.1.6 The concave surface shall face down whenever the resulting center of rotation is not detrimental to the system geometry.
See Fig. 1.
5.1.7 The minimum thickness at the center of the concave spherical element shall be ⁄4 in. (19 mm).
5.1.8 The minimum thickness at the edge of the convex spherical element shall be ⁄2 in. (12.7 mm).
5.1.9 Vertical and horizontal clearance between the rotating (attached to the superstructure) and non-rotating (attached to the
substructure) spherical bearing components, including fasteners, shall be no less than ⁄8 in. (3.17 mm) when rotated to 150 % of
the design rotation.
NOTE 2—To Designer: The spherical PTFE pad may be damaged at 150 % of the design rotation.
5.1.10 The concave radius shall be machined to a tolerance of − 0.000, + 0.010 in. (−0, + 0.25of −0.000, +0.010 in. (−0, +0.25
mm).
FIG. 1 Views of a Spherical Bearing
D5977 − 23
5.1.11 The convex radius shall be machined
...
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