1、Designation: D 5977 03Standard 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 revision, the year
2、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 stainless steel c
3、onvexsurface 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 T
4、his 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 valuesd
5、ue 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
6、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 ASTM Standards:A
7、36/A 36M Specification for Carbon Structural Steel2A 167 Specification for Stainless and Heat-ResistingChromium-Nickel Steel Plate, Sheet, and Strip3A 240/A 240M Specification for Chromium andChromium-Nickel Stainless Steel Plate, Sheet, and Stripfor Pressure Vessels and General Applications3A 572/A
8、 572M Specification for High-Strength Low-AlloyColumbium-Vanadium Structural Steel2A 588/A 588M Specification for High-Strength Low-AlloyStructural Steel with 50 ksi 345 MPa Minimum YieldPoint to 4 in. 100 mm Thick2A 709/A 709M Specification for Carbon and High-StrengthLow-Alloy Structural Steel Sha
9、pes, Plates, and Bars andQuenched-and-Tempered Alloy Structural Steel Plates forBridges2D 638 Test Method for Tensile Properties of Plastics4D 792 Test Methods for Density and Specific Gravity (Rela-tive Density) of Plastics by Displacement4D 1457 Specification for Polytetrafluoroethylene (PTFE)Mold
10、ing and Extrusion Materials4D 1777 Method for Measuring Thickness of Textile Mate-rials5D 2256 Test Method for Tensile Properties of Yarns by theSingle-Strand Method52.2 AASHTO Standard:AASHTO Standard Specifications for Highway Bridges62.3 AWS Standards:7C.2.2-67 Metalizing with Aluminum and Zinc f
11、or Protec-tion of Iron and SteelD.1.5 ANSI/AASHTO/AWS Bridge Welding Code3. Classification3.1 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
12、 Sliding Spherical BearingRotation plus movement in all directions.4. Material Specifications4.1 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 metal
13、ized according to AWSC.2.2-67 (with no chipping), having a minimum thickness of 61This 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 Feb. 10, 2003. Pu
14、blished May 2003. Originallyapproved in 1996. Last previous edition approved in 1996 as D 5977-96.2Annual Book of ASTM Standards, Vol 01.04.3Annual Book of ASTM Standards, Vol 01.03.4Annual Book of ASTM Standards, Vol 08.01.5Annual Book of ASTM Standards, Vol 07.01.6Available from American Associati
15、on of State Highway and TransportationOfficials (AASHTO), 444 N. Capitol St., NW, Suite 249, Washington, DC 20001.7Available from American Welding Society, 550 N.W. Lejeune Rd., Miami, FL33135.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United
16、 States.mil (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 paint system must be speci-fied by the owner.4.2 Stainless Steel:4.2.1 Flat Sliding SurfaceThe sheet stainless steel used asthe mating sl
17、iding 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 mating rotational convexsurface to th
18、e 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 virgin PTFE orientedmultifilament fibe
19、rs with or without a high-strength backing.4.3.1 The thickness of the woven fabric PTFE in the freestate shall be a minimum of332in. (2.38 mm) when measuredin accordance with Method D 1777.4.3.2 The thickness of the bonded woven fabric PTFE underthe application of vertical load shall be a minimum of
20、 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 thatprevents migration of the epoxy
21、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 cut fabricedges are exposed.4.3.4 The
22、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. The PTFE shall be resistant toacids,
23、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 thickness of the sheet PTFE shall be
24、 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 RequirementsNOTE 1To Designer: The bearing details shall be designed in accor-da
25、nce 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 theresulting geometry of the bearing is capable of withstandi
26、ngthe 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 shall be prevented by transferring horizontal forcesthrough
27、 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:ratio = worst case ratio of horizontal to vertical loads.a5
28、SarcsinSd/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 horizontal to vertical load case.5.1.4 Calculations showi
29、ng 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 surface shall face down whenever theresulting center of
30、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. (12.7 mm).TABLE 1 Physical Property Requirements for Wov
31、en 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, min, psi (MPa) D 638 2800
32、(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).D59770325.1.9 Vertical and horizontal clearance between the rotating(attached to the superstructure) and non-rotating (attached tothe substructu
33、re) spherical bearing components, includingfasteners, shall be no less than18 in. (3.17 mm) when rotatedto 150 % of the design rotation.NOTE 2To 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
34、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 minimum thickness of 0.059 in.(1.5 mm).5.2.2 Fixing of the Stain
35、less 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 and that interface corrosion cannot occur. Theattachment of the
36、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 steel sheet to accommodate the weld; also, the weldmust not protrud
37、e 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 operations, plus oneadditional in. (25.4 mm) in all directions of movemen
38、t. 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 inter-locked to the steel substrate. An epoxy bond system shall be
39、used 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 fabric PTFE shall be designedfor a maximum average working stress
40、 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, meetingthe requirements of Specification D 1457. The sheet PTFEshall b
41、e 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 designed for amaximum average working stress of 3500 psi (24.1 N/mm2).5
42、.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 Guiding Surfaces:5.5.1 Attachment of the sheet PTFE to the steel s
43、ubstrate 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 PTFE andlocated12 in. (12.7 mm) from each end of the PTFE strip.
44、 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 sodiumammonia etching process.5.6 Guide Bars:5.6.1 Each guide bar shall be
45、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 Guided surfaces shall be faced with opposing strips ofstainless
46、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 PTFEshall be bonded as well as fastened mechanically with stainlessstee
47、l screws (see 5.5.1). The maximum total gap allowedbetween the guiding surfaces shall be116in. (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 not less than 10 % of the maximum working stressload on the bear
48、ing.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 against thefixed base or any extension of it is not recommended.F
49、IG. 1 Views of a Spherical BearingD59770335.7 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 shipment by the manufacturer.A lot shall be defined as those bearings presented for inspectionat a specific time and date.6.1.2 A lot shall not exceed 25 bearings.6.1.3 A lo
