1、Designation: D 5977 03 (Reapproved 2007)Standard Specification forHigh Load Rotational Spherical Bearings for Bridges andStructures1This standard is issued under the fixed designation D 5977; the number immediately following the designation indicates the year oforiginal adoption or, in the case of r
2、evision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This specification covers bridge bearings that consist ofa spherical rotational element, where a
3、 stainless steel convexsurface slides against a concave carbon steel plate covered withwoven or sheet polytetrafluoroethylene (PTFE). The functionof the bearing is to transfer loads and to accommodate anyrelative movement, including rotation between a bridge super-structure and its supporting struct
4、ure, or both.1.2 This specification covers the requirements of sphericalbearings with a standard horizontal load (a maximum of 10 %of vertical).1.3 The requirements stated in this specification are theminima necessary for the manufacture of quality bearingdevices. It may be necessary to increase the
5、se minimum valuesdue to other design conditions.1.4 The values stated in inch-pound units are to be regardedas the standard. The values given in parentheses are forinformation only.1.5 The following safety hazards caveat pertains only to thetest method portion, Section 7, of this specification: This
6、standard does not purport to address all of the safety concerns,if any, associated with its use. It is the responsibility of the userof this standard to establish appropriate safety and healthpractices and determine the applicability of regulatory limita-tions prior to use.2. Referenced Documents2.1
7、 ASTM Standards:2A 36/A 36M Specification for Carbon Structural SteelA 167 Specification for Stainless and Heat-ResistingChromium-Nickel Steel Plate, Sheet, and StripA 240/A 240M Specification for Chromium andChromium-Nickel Stainless Steel Plate, Sheet, and Stripfor Pressure Vessels and for General
8、 ApplicationsA 572/A 572M Specification for High-Strength Low-AlloyColumbium-Vanadium Structural SteelA 588/A 588M Specification for High-Strength Low-AlloyStructural Steel, up to 50 ksi 345 MPa Minimum YieldPoint, with Atmospheric Corrosion ResistanceA 709/A 709M Specification for Structural Steel
9、forBridgesD 638 Test Method for Tensile Properties of PlasticsD 792 Test Methods for Density and Specific Gravity (Rela-tive Density) of Plastics by DisplacementD 1457 Specification for Polytetrafluoroethylene (PTFE)Molding and Extrusion MaterialsD 1777 Test Method for Thickness of Textile Materials
10、D 2256 Test Method for Tensile Properties of Yarns by theSingle-Strand Method2.2 AASHTO Standard:3AASHTO Standard Specifications for Highway Bridges2.3 AWS Standards:4C.2.2-67 Metalizing with Aluminum and Zinc for Protec-tion of Iron and SteelD.1.5 ANSI/AASHTO/AWS Bridge Welding Code3. Classificatio
11、n3.1 The bearings are furnished in three types, as follows:3.1.1 Fixed Spherical BearingRotation only.3.1.2 Uni-Directional Sliding Spherical BearingRotationplus movement in one direction.3.1.3 Multi-Directional Sliding Spherical BearingRotation plus movement in all directions.4. Material Specificat
12、ions4.1 SteelThe steel used for all major plates shall bestructural steel conforming to Specifications A 36/A 36M, A588/A 588M, A 572/A 572M, or A 709/A 709M, as required.All exposed surfaces shall be zinc metalized according toAWSC.2.2-67 (with no chipping), having a minimum thickness of 6mil (0.15
13、2 mm) or treated with other project-approved coating1This specification is under the jurisdiction of ASTM Committee D04 on Roadand Paving Materials and is the direct responsibility of Subcommittee D04.32 onBridges and Structures.Current edition approved Dec. 1, 2007. Published January 2008. Original
14、lyapproved in 1996. Last previous edition approved in 2003 as D 5977 03.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe AS
15、TM website.3Available from American Association of State Highway and TransportationOfficials (AASHTO), 444 N. Capitol St., NW, Suite 249, Washington, DC 20001,http:/www.transportation.org.4Available from American Welding Society (AWS), 550 NW LeJeune Rd.,Miami, FL 33126, http:/www.aws.org.1Copyright
16、 ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.systems such as coal tar or inorganic zinc paint. The dry filmthickness (DFT) of the approved paint system must be speci-fied by the owner.4.2 Stainless Steel:4.2.1 Flat Sliding SurfaceThe sheet
17、stainless steel used asthe mating sliding surface to the woven fabric PTFE or sheetPTFE in the sliding spherical bearings shall conform toSpecification A 167 or A 240/A 240M, type 304, 20-in. (0.5-m) rms finish.4.2.2 Convex SurfaceThe solid stainless steel plate orsheet stainless steel used as the m
18、ating rotational convexsurface to the woven fabric PTFE or sheet PTFE shall conformto Specification A 167 or A 240/A 240M, type 304. Thesurface shall be machined to a surface finish of 20-in.(0.5-m) rms or less.4.3 Woven Fabric Polytetrafluoroethylene (PTFE)Thewoven fabric PTFE shall be made from vi
19、rgin PTFE orientedmultifilament fibers with or without a high-strength backing.4.3.1 The thickness of the woven fabric PTFE in the freestate shall be a minimum of332 in. (2.38 mm) when measuredin accordance with Method D 1777.4.3.2 The thickness of the bonded woven fabric PTFE underthe application o
20、f vertical load shall be a minimum of thefollowing:(1)116 in. (1.59 mm) from 0 psi (0 N/mm2) to 3500 psi(24.1 N/mm2).(2)364 in. (1.19 mm) from 3501 psi (24.1 N/mm2) to 4500psi (31.0 N/mm2).4.3.3 The woven fabric PTFE shall be mechanically inter-locked and epoxy-bonded to the substrate using a system
21、 thatprevents migration of the epoxy through the fabric. The use ofa mechanical interlock system along with the epoxy increasesthe bond strength, providing a redundancy for the prevention ofmigration of the PTFE material. Any edges, other than theselvedge (woven edge), shall be oversewn so that no c
22、ut fabricedges are exposed.4.3.4 The individual PTFE filaments used in making thewoven PTFE fabric shall conform to the physical requirementsof Table 1.4.4 Sheet Polytetrafluoroethylene (PTFE)The sheet PTFEshall be virgin material (not reprocessed) meeting the require-ments of Specification D 1457.
23、The PTFE shall be resistant toacids, alkalis, petroleum products, and nonabsorbtion of water.It shall be stable for temperatures up to 500F (260C) andshall be nonflammable. When used in PTFE surfaces used forguide bars only, filler material shall be composed of milledglass fibers or carbon.4.4.1 The
24、 thickness of the sheet PTFE shall be a minimumof18 in. (3.17 mm) and shall be recessed at least one-half of itsthickness.4.4.2 The PTFE for the principal slide surface and for guidebars shall conform to the physical requirements listed in Table2.5. Design Requirements Design RequirementsNOTE 1To De
25、signer: The bearing details shall be designed in accor-dance with the requirements of the current edition with interims of theAASHTO Standard Specifications for Highway Bridges or other govern-ing design procedures.5.1 Rotational Elements:5.1.1 The spherical radius shall be determined such that ther
26、esulting geometry of the bearing is capable of withstandingthe greatest ratio of the horizontal load to vertical load under allloading conditions to prevent the unseating (separation at theedges) of the convex/concave elements.5.1.2 Unseating of the curved spherical surfaces relative toeach other sh
27、all be prevented by transferring horizontal forcesthrough specifically designed restraints or by control of thespherical radius.5.1.3 Acceptable spherical radius control shall be givenwhen the configuration of the woven fabric PTFE concaveradius follows the following design:ratio#tan a (1)where:rati
28、o = worst case ratio of horizontal to vertical loads.a5SarcsinSd/2RmaxDD2 design rotation! (2)where:d = projected diameter of the woven fabricPTFE,design rotation = design rotation of the bearing (in de-grees), andRmax = maximum allowable radius to preventuplift within the bearing during theworst ho
29、rizontal to vertical load case.5.1.4 Calculations showing determination of the radius shallbe submitted for approval.5.1.5 The radius of the convex plate shall be less than theradius calculated for the woven fabric PTFE (concave plate) bya value equal to the thickness of the PTFE.5.1.6 The concave s
30、urface shall face down whenever theresulting center of rotation is not detrimental to the systemgeometry. See Fig. 15.1.7 The minimum thickness at the center of the concavespherical element shall be34 in. (19 mm).5.1.8 The minimum thickness at the edge of the convexspherical element shall be12 in. (
31、12.7 mm).5.1.9 Vertical and horizontal clearance between the rotating(attached to the superstructure) and non-rotating (attached tothe substructure) spherical bearing components, includingfasteners, shall be no less than18 in. (3.17 mm) when rotatedto 150 % of the design rotation.TABLE 1 Physical Pr
32、operty Requirements for Woven PTFEPhysical Properties Test Method RequirementUltimate tensile strength, min, psi (MPa) D 2256 24 000 (165.4)Ultimate elongation, min, % D 2256 35TABLE 2 Physical Property Requirements for Sheet PTFEAPhysical Properties Test Method RequirementUltimate tensile strength,
33、 min, psi (MPa) D 638 2800 (19.3)Ultimate elongation, min, % D 638 200Specific gravity, min D 792 2.12A15 % glass-filled PTFE may be used for guide bar surfaces (SpecificationD 1457).D 5977 03 (2007)2NOTE 2To Designer: The spherical PTFE pad may be damaged at150 % of the design rotation.5.1.10 The c
34、oncave radius shall be machined to a toleranceof 0.000, + 0.010 in. (0, + 0.25 mm).5.1.11 The convex radius shall be machined to a toleranceof 0.010, + 0.000 in. (0.25, + 0 mm).5.2 Stainless Steel Sliding Surface:5.2.1 The thickness of the stainless steel sheet shall be 11gage, with a manufacturers
35、minimum thickness of 0.059 in.(1.5 mm).5.2.2 Fixing of the Stainless Steel SheetThe stainless steelsheet shall be attached to its backing plate by continuous filletwelding along its edges. It is essential that the stainless steelsheet remain in contact with the base metal throughout itsservice life
36、and that interface corrosion cannot occur. Theattachment of the stainless steel to its back-up plate shall becapable of resisting the frictional force set up in the bearing.Welding must be in accordance with ANSI/AASHTO/AWSD1.5.5.2.3 The backing plate shall extend beyond the edge of thestainless ste
37、el sheet to accommodate the weld; also, the weldmust not protrude above the stainless steel sheet. TIG weldingof the stainless steel sheet is highly recommended to achievethis connection.5.2.4 The flat horizontal stainless steel sliding surface shallcover the PTFE surface completely in all operation
38、s, plus oneadditional in. (25.4 mm) in all directions of movement. For aguided bearing with which there is no transverse movement,this requirement does not apply in the transverse direction.5.3 Woven Fabric PTFE Concave or Sliding Surfaces, orBoth:5.3.1 The woven fabric PTFE shall be mechanically in
39、ter-locked to the steel substrate. An epoxy bond system shall beused for additional security. After completion of the bondingoperation, the PTFE surface shall be smooth and free fromblisters, bubbles, and evidence that any epoxy has migratedthrough the woven fabric PTFE.5.3.2 The area of the woven f
40、abric PTFE shall be designedfor a maximum average working stress of 4500 psi (31.0N/mm2).5.3.3 The maximum edge pressure on the woven fabricPTFE shall not exceed 10 000 psi (68.8 N/mm2).5.4 Sheet PTFE on Concave or Sliding Surfaces, or Both:5.4.1 The sheet PTFE shall be pure virgin, unfilled, meetin
41、gthe requirements of Specification D 1457. The sheet PTFEshall be recessed to one-half of its thickness and epoxy bondedto the steel substrate. The PTFE surface shall be smooth andfree from blisters or bubbles after completion of the bondingoperation.5.4.2 The area of the sheet PTFE shall be designe
42、d for amaximum average working stress of 3500 psi (24.1 N/mm2).5.4.3 The maximum edge pressure on the sheet PTFE shallnot exceed 5000 psi (34.4 N/mm2).5.4.4 The surface of the PTFE sheet to be epoxy bondedshall be etched using the sodium naphthalene or sodiumammonia etching process.5.5 Sheet PTFE Gu
43、iding Surfaces:5.5.1 Attachment of the sheet PTFE to the steel substrate ofthe guiding surface shall be performed by epoxy bonding andmechanical fastening. The mechanical fastening shall consistof a minimum of two stainless steel screws (SpecificationA 304) located on the centerline of the strip of
44、PTFE andlocated12 in. (12.7 mm) from each end of the PTFE strip. Thetop of the screws shall be recessed a minimum of 50 % of theamount of protrusion of the PTFE above the steel substrate.5.5.2 The surface of the PTFE sheet to be epoxy bondedshall be etched using the sodium naphthalene or sodiumammon
45、ia etching process.5.6 Guide Bars:5.6.1 Each guide bar shall be manufactured from a mono-lithic piece of steel. Guide bars may be made integral bymachining from the solid shape or fabricated from solid barsthat are welded, bolted, or recessed into the guiding plate, orsome combination thereof.5.6.2
46、Guided surfaces shall be faced with opposing strips ofstainless steel and sheet PTFE. No metal-to-metal contact shallbe permitted. The sheet PTFE may be fastened to either theconcave plate or guide bars, with opposing stainless steel onthe guide bars or concave plate, respectively. The sheet PTFEsha
47、ll be bonded as well as fastened mechanically with stainlesssteel screws (see 5.5.1). The maximum total gap allowedbetween the guiding surfaces shall be116 in. (1.59 mm).5.6.3 The guide bars and their connections to the sliding/sole plate shall be designed for the horizontal forces on thebearing but
48、 not less than 10 % of the maximum working stressload on the bearing.5.6.4 Guiding arrangements shall be designed so that thePTFE-covered guide surface is kept parallel and always withinthe limits of the stainless steel-covered guides at all points oftranslation and rotation of the bearing. Guiding
49、against thefixed base or any extension of it is not recommended.5.7 FlatnessAll bearing load carrying surfaces in contactwith one another shall be flat within 0.006 in. (0.13 mm) perany 12 in. (305 mm), as determined by a precision straightedgeand feeler gages or by other approved methods.FIG. 1 Views of a Spherical BearingD 5977 03 (2007)36. Sampling6.1 Lot Size:6.1.1 Sampling, testing, and acceptance consideration willbe made on a lot basis prior to shipment by the manufacturer.Alot shall be defined as those bearings presented for inspection
