1、Designation: D5977 15Standard Specification forHigh Load Rotational Spherical Bearings for Bridges andStructures1This standard is issued under the fixed designation D5977; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of
2、 last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () 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 stainless steel conv
3、exsurface 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 structure, or both.1.2 This
4、 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 these minimum valuesdue
5、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: Thisstandard does not pur
6、port 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 ASTM Standards:2A36/
7、A36M Specification for Carbon Structural SteelA167 Specification for Stainless and Heat-ResistingChromium-Nickel Steel Plate, Sheet, and Strip (With-drawn 2014)3A240/A240M Specification for Chromium and Chromium-Nickel Stainless Steel Plate, Sheet, and Strip for PressureVessels and for General Appli
8、cationsA572/A572M Specification for High-Strength Low-AlloyColumbium-Vanadium Structural SteelA588/A588M Specification for High-Strength Low-AlloyStructural Steel, up to 50 ksi 345 MPa Minimum YieldPoint, with Atmospheric Corrosion ResistanceA709/A709M Specification for Structural Steel for BridgesD
9、638 Test Method for Tensile Properties of PlasticsD792 Test Methods for Density and Specific Gravity (Rela-tive Density) of Plastics by DisplacementD1457 Specification for Polytetrafluoroethylene (PTFE)Molding and Extrusion Materials (Withdrawn 1996)3D1777 Test Method for Thickness of Textile Materi
10、alsD2256 Test Method for Tensile Properties of Yarns by theSingle-Strand Method2.2 AASHTO Standard:4AASHTO Standard Specifications for Highway Bridges2.3 AWS Standards:5C.2.2-67 Metalizing withAluminum and Zinc for Protectionof Iron and SteelD.1.5 ANSI/AASHTO/AWS Bridge Welding Code3. Classification
11、3.1 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.1This specification is
12、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 June 1, 2015. Published July 2015. Originally approvedin 1996. Last previous edition approved in 2012 as D5977 03 (2012).
13、 DOI:10.1520/D5977-15.2For 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 ASTM website.3The last approved version of this hist
14、orical standard is referenced onwww.astm.org.4Available from American Association of State Highway and TransportationOfficials (AASHTO), 444 N. Capitol St., NW, Suite 249, Washington, DC 20001,http:/www.transportation.org.5Available from American Welding Society (AWS), 550 NW LeJeune Rd.,Miami, FL 3
15、3126, http:/www.aws.org.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States14. Material Specifications4.1 SteelThe steel used for all major plates shall bestructural steel conforming to Specifications A36/A36M,A588/A588M, A572/A572M,orA70
16、9/A709M, as required.All exposed surfaces shall be zinc metalized according toAWSC.2.2-67 (with no chipping), having a minimum thickness of 6mil (0.152 mm) or treated with other project-approved coatingsystems such as coal tar or inorganic zinc paint. The dry filmthickness (DFT) of the approved pain
17、t system must be speci-fied by the owner.4.2 Stainless Steel:4.2.1 Flat Sliding SurfaceThe sheet stainless steel used asthe mating sliding surface to the woven fabric PTFE or sheetPTFE in the sliding spherical bearings shall conform toSpecification A167 or A240/A240M, type 304, 20-in. (0.5-m) rms fi
18、nish.4.2.2 Convex SurfaceThe solid stainless steel plate orsheet stainless steel used as the mating rotational convexsurface to the woven fabric PTFE or sheet PTFE shall conformto Specification A167 or A240/A240M, type 304. The surfaceshall be machined to a surface finish of 20-in. (0.5-m) rms orles
19、s.4.3 Woven Fabric Polytetrafluoroethylene (PTFE)Thewoven fabric PTFE shall be made from virgin 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 wi
20、th Method D1777.4.3.2 The thickness of the bonded woven fabric PTFE underthe application of vertical load (excluding any backing mate-rial) shall be a minimum of the following:(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
21、 (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 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 th
22、e prevention ofmigration of the PTFE material. Any edges, other than theselvedge (woven edge), shall be oversewn so that no cut 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 Polytetrafluo
23、roethylene (PTFE)The sheet PTFEshall be virgin material (not reprocessed) meeting the require-ments of Specification D1457. 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. Whe
24、n used in PTFE surfaces used forguide bars only, filler material shall be composed of milledglass fibers or carbon.4.4.1 The 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
25、 guidebars shall conform to the physical requirements listed in Table2.5. Design RequirementsNOTE 1To Designer: The bearing details shall be designed inaccordance with the requirements of the current edition with interims ofthe AASHTO Standard Specifications for Highway Bridges or othergoverning des
26、ign procedures.5.1 Rotational Elements:5.1.1 The spherical radius shall be determined such that theresulting 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 t
27、he convex/concave elements.5.1.2 Unseating of the curved spherical surfaces relative toeach other shall 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 configu
28、ration of the woven fabric PTFE concaveradius follows the following design:ratio# tan (1)where:ratio = worst case ratio of horizontal to vertical loads. 5SarcsinSd/2RmaxDD2 design rotation! (2)where:d = projected diameter of the woven fabricPTFE,design rotation = design rotation of the bearing (inde
29、grees), andRmax = maximum allowable radius to preventuplift within the bearing during the worsthorizontal 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 w
30、oven fabric PTFE (concave plate) bya value equal to the thickness of the PTFE.5.1.6 The concave surface shall face down whenever theresulting center of rotation is not detrimental to the systemgeometry. See Fig. 1TABLE 1 Physical Property Requirements for Woven PTFEPhysical Properties Test Method Re
31、quirementUltimate tensile strength, min, psi (MPa) D2256 24 000 (165.4)Ultimate elongation, min, % D2256 10 % # 35 %TABLE 2 Physical Property Requirements for Sheet PTFEAPhysical Properties Test Method RequirementUltimate tensile strength, min, psi (MPa) D638 2800 (19.3)Ultimate elongation, min, % D
32、638 200Specific gravity, min D792 2.12A15 % glass-filled PTFE may be used for guide bar surfaces (SpecificationD1457).D5977 1525.1.7 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
33、 be12 in. (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.NOTE 2To
34、 Designer: The spherical PTFE pad may be damaged at150 % of the design rotation.5.1.10 The concave 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 Sur
35、face:5.2.1 The thickness of the stainless steel sheet shall be 11gage, with a manufacturers 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 tha
36、t the stainless steelsheet remain in contact with the base metal throughout itsservice life 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
37、ANSI/AASHTO/AWSD1.5.5.2.3 The backing plate shall extend beyond the edge of thestainless steel 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 horizo
38、ntal stainless steel sliding surface shallcover the PTFE surface completely in all operations, 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 P
39、TFE Concave or Sliding Surfaces, orBoth:5.3.1 The woven fabric PTFE shall be mechanically inter-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 evi
40、dence that any epoxy has migratedthrough the woven fabric PTFE.5.3.2 The area of the woven fabric 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 Conc
41、ave or Sliding Surfaces, or Both:5.4.1 The sheet PTFE shall be pure virgin, unfilled, meetingthe requirements of Specification D1457. The sheet PTFE shallbe recessed to one-half of its thickness and epoxy bonded to thesteel substrate. The PTFE surface shall be smooth and freefrom blisters or bubbles
42、 after completion of the bondingoperation.5.4.2 The area of the sheet PTFE shall be designed 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 bondedshal
43、l be etched using the sodium naphthalene or sodiumammonia etching process.5.5 Sheet PTFE Guiding 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
44、 two stainless steel screws (SpecificationA304) located on the centerline of the strip of 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 th
45、e PTFE sheet to be epoxy bondedshall be etched using the sodium naphthalene or sodiumammonia 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
46、 are welded, bolted, or recessed into the guiding plate, orsome combination thereof.5.6.2 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 o
47、pposing stainless steel onthe guide bars or concave plate, respectively. The sheet PTFEshall 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 connectio
48、ns to the sliding/sole plate shall be designed for the horizontal forces on thebearing but not less than 10 % of the maximum working stressload on the bearing.FIG. 1 Views of a Spherical BearingD5977 1535.6.4 Guiding arrangements shall be designed so that thePTFE-covered guide surface is kept parall
49、el and always withinthe limits of the stainless steel-covered guides at all points oftranslation and rotation of the bearing. Guiding 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.6. Sampling6.1 Lot Size:6.1.1 Sampling, testing, and acceptance consideration willbe made on a lot basis prior to shipmen
