1、Standard Specification for Plain and Laminated Elastomeric Bridge Bearings AASHTO Designation: M 251-06 (2016)1Release: Group 2 (June 2016) American Association of State Highway and Transportation Officials 444 North Capitol Street N.W., Suite 249 Washington, D.C. 20001 TS-4e M 251-1 AASHTO Standard
2、 Specification for Plain and Laminated Elastomeric Bridge Bearings AASHTO Designation: M 251-06 (2016)1Release: Group 2 (June 2016) 1. SCOPE 1.1. This specification covers the material requirements for plain and laminated elastomeric bridge bearings. Elastomeric bearings furnished under this specifi
3、cation shall adequately provide for thermal expansion and contraction, rotation, camber changes, and creep and shrinkage, where applicable, of structural members. Elastomeric bearings as herein defined shall include plain pads (consisting of elastomer only) and laminated bearings with steel or fabri
4、c laminates. 2. REFERENCED DOCUMENTS 2.1. AASHTO Publications: Standard Specifications for Highway Bridges AASHTO LRFD Bridge Design Specifications 2.2. ASTM Standards: A36/A36M, Standard Specification for Carbon Structural Steel A1011/A1011M, Standard Specification for Steel, Sheet and Strip, Hot-R
5、olled, Carbon, Structural, High-Strength Low-Alloy, High-Strength Low-Alloy with Improved Formability, and Ultra-High Strength D412, Standard Test Methods for Vulcanized Rubber and Thermoplastic ElastomersTension D746, Standard Test Method for Brittleness Temperature of Plastics and Elastomers by Im
6、pact D751, Standard Test Methods for Coated Fabrics D3183, Standard Practice for RubberPreparation of Pieces for Test Purposes from Products D4014, Standard Specification for Plain and Steel-Laminated Elastomeric Bearings for Bridges E4, Standard Practices for Force Verification of Testing Machines
7、E29, Standard Practice for Using Significant Digits in Test Data to Determine Conformance with Specifications 2.3. ANSI Standard: ANSI B46.1, Surfaces and Surfacing 2.4. The Association for Rubber Products Manufacturers (ARPM):2 The ARPM Rubber Handbook for Molded, Extruded, Lathe Cut and Cellular P
8、roducts, MO-1 (https:/ 2016 by the American Association of State Highway and Transportation Officials. All rights reserved. Duplication is a violation of applicable law.TS-4e M 251-2 AASHTO Table 6RMA Drawing Designation for Finish, RMA F2, Satin Finish Table 6RMA Drawing Designation for Finish, RMA
9、 F3, Commercial Finish Table 7RMA Drawing Designation for Flash Extension, RMA T 1.60 mm T .063, Normal Tear Trim Tolerance 2.5. The Society for Protective Coatings (SSPC) Specification:3 SSPC-VIS 1-01, Visual Standard for Abrasive Blast Cleaned Steel 3. GENERAL REQUIREMENTS 3.1. All bearings shall
10、be designed in accordance with specifications contained in the latest edition of AASHTOs Standard Specifications for Highway Bridges or the AASHTO LRFD Bridge Design Specifications. 3.2. The dimensions of the furnished bearings shall be the dimensions required by the design documents within the tole
11、rances shown in Section 6 of this specification. The bearings shall be composed of the specified materials, shall be tested at the appropriate level, and shall satisfy any special requirements of the purchaser. 3.3. The contractor shall provide the purchaser with written notification 30 days prior t
12、o the start of bearing production. This notification shall include the contract number, quantity, and size of bearings being produced, as well as the manufacturers name, location, and the representative who will coordinate production, inspection, sampling, and testing with the purchaser. 3.4. Testin
13、g for the physical properties of the elastomer may require the destruction of one or more bearings from a lot. In these instances, the cost of providing additional bearings for testing purposes shall be borne by the supplier. 3.5. At the owners discretion, bearings specified by hardness and designed
14、 in accordance with Method A of the AASHTO LRFD Bridge Design Specifications or AASHTOs Standard Specifications for Highway Bridges may be tested and accepted in accordance with Appendix X1 in lieu of Section 8. 3.6. In addition to material requirements for the bearings individual components, this s
15、pecification provides acceptance criteria for finished bearings. 3.7. Perform calculations using significant digits in accordance with ASTM E29 using the rounding method for determining compliance to the specification requirements herein, unless otherwise specified by the purchaser. 4. MATERIALS 4.1
16、. Properties of the ElastomerThe elastomer compound used in the construction of these bearings shall contain only virgin crystallization resistant polychloroprene (neoprene) or virgin natural polyisoprene (natural rubber) as the raw polymer. All materials shall be new with no reclaimed material inco
17、rporated in the finished bearing. The elastomer compounds shall be classified as being of low-temperature Grade 0, 2, 3, 4, or 5 as specified by the minimum grade requirements of Table 14.7.5.2-2, “Low Temperature Zones and Minimum Grade of Elastomer,” of the AASHTO LRFD Bridge Design Specifications
18、. Low temperature zones used in this table are as defined in Figure 14.7.5.2-1, “Temperature Zones,” of the same publication. 2016 by the American Association of State Highway and Transportation Officials. All rights reserved. Duplication is a violation of applicable law.TS-4e M 251-3 AASHTO 4.1.1.
19、The cured elastomer shall meet the minimum requirements of Table 1. The properties of the cured elastomeric compound material listed in Table 1 shall be determined using samples taken from actual bearings. Table 1Elastomer Properties Material Property ASTM Standard Test Requirement Polyisoprene (Nat
20、ural Rubber) Polychloroprene (Neoprene) Units Physical properties See Section 8.8.4 D412 Min shear modulus 0.55 79.7707 0.55 79.7707 MPa psi Min tensile strength 15.5 2248.085 15.5 2248.085 MPa psi Min ultimate elongation 450 400 % Low-temperature brittleness D746 Procedure B Grades 0 and 2No test r
21、equired Grade 3Test at 40C 40F Passes Passes Grade 4Test at 48C 54.4F Passes Passes Grade 5Test at 57C 70.6F Passes Passes 4.1.2. All material tests shall be carried out at 23 2C 73.4 3.6F unless otherwise noted. 4.1.3. For the purpose of determining conformance with this specification, an observed
22、or calculated value shall be rounded off to the nearest 100 kPa 14.5038 psi for tensile strength, to the nearest 10 percent for elongation, and to the nearest 0.01 MPa 1.4504 psi for shear modulus. 4.2. Steel LaminatesSteel laminates used for reinforcement shall be made from rolled mild steel confor
23、ming to ASTM A36/A36M, ASTM A1011/A1011M, or equivalent, unless otherwise specified by the purchaser. The laminates shall be of the thickness specified by the purchaser or, if left unspecified, have a minimum nominal thickness of 1.52 mm 0.0598 in. Holes in plates for manufacturing purposes shall no
24、t be permitted unless considered in the design of the bearing. 4.3. External Load-Bearing PlatesExternal load-bearing plates shall conform to the requirements of ASTM A36/A36M, ASTM A1011/A1011M, or equivalent, unless otherwise specified in the contract documents. Except as noted, all bearings surfa
25、ces of external load-bearing plates shall be finished or machined flat within 0.25 mm 0.0098 in. The bottom surfaces of external load-bearing plates (masonry plates) designed to rest on bearing pads shall not exceed an out-of-flatness value of 1.59 mm 0.0626 in. The external load-bearing plates shal
26、l be protected from rust until all exposed surfaces can be field painted. Any rust inhibitor utilized must be removed from all surfaces to be welded prior to welding. 4.4. Fabric LaminatesFabric laminates shall be woven from 100 percent glass fibers of “E” type yarn with continuous fibers. The minim
27、um thread count in either direction shall be 10 threads per cm. The fabric shall have either a crowfoot or an eight-harness satin weave. Each ply of fabric shall have a minimum tensile strength of 140 kN/m 799.4208 lbf/in. of width in each thread direction, which shall be determined by ASTM D751. 5.
28、 FABRICATION 5.1. Bearings with steel laminates shall be cast as a unit in a mold and bonded and vulcanized under heat and pressure. The molds shall have standard shop practice mold finish. The internal steel laminates shall be blast cleaned to a condition matching that of SSPC-VIS 1-01, Pictorial S
29、tandard BSP6 or CSP6, and additionally cleaned of any oil or grease before bonding. Plates shall be free of sharp edges and burrs, and shall have a minimum edge cover of 6 mm 0.2363 in. External load plates (sole plates) shall be protected from rusting by the manufacturer, and shall be hot bonded to
30、 the bearing during vulcanization. Bearings with steel laminates that are designed to act as a single unit with a given shape factor must be manufactured as a single unit. 2016 by the American Association of State Highway and Transportation Officials. All rights reserved. Duplication is a violation
31、of applicable law.TS-4e M 251-4 AASHTO 5.2. Fabric-laminated bearings may be molded and vulcanized in large sheets and cut to size. Cutting shall be performed so as to avoid heating the materials and produce a smooth finish with no separation of the fabric from the elastomer. Fabric shall be free of
32、 folds and ripples and shall be parallel to the top and bottom surfaces. If external steel plates are required, a cold bonding process that will yield the strengths required in Section 8.8 of this specification may be used in lieu of hot bonding. 5.3. Plain pads may be molded or extruded and vulcani
33、zed in large sheets and cut to size. Cutting shall not heat the materials, and shall produce a smooth finish to ANSI B46.1, 6.3 m 248 in. Plain pads shall be molded or extruded to the finished thickness. Fabricators will not be allowed to make pads of finished thickness by plying pads of lesser thic
34、kness together. External load plates, when used, shall be protected from rusting by the manufacturer and shall be hot bonded by vulcanization during the primary molding process. 5.4. Flash tolerance, finish, and appearance of bearings shall meet the requirements of the latest edition of the Rubber H
35、andbook as published by The Association for Rubber Products Manufacturers (ARPM), RMA F3 and T .063 for molded bearings and RMA F2 for extruded bearings. 6. TOLERANCES 6.1. Plain pads and laminated bearings shall be manufactured to the design dimensions tolerances listed in Table 2, unless other tol
36、erances are shown on the design drawings. Use the following equation to define alignment tolerance limits for steel laminate when tolerance #3 (3 mm) 0.1181 in. is exceeded: 7.5 + v/hr 0.35 provided 0.02 where (radians) and v (mm) in. are absolute values of steel laminate rotation and vertical displ
37、acement. If the specified elastomeric layer thickness is hr , the bearing length is L, and H1 and H2 are the measured maximum and minimum thicknesses at the edges of the layer, then v = |hr 0.5 (H1 + H2 )| and = |(H1 H2 )/ 2L| for interior layers and = |(H1 H2 ) / L| for top and bottom layers, provi
38、ded that the minimum elastomer layer thickness H2 5 mm 0.1968 in. Bearings with tolerances that satisfy this equation must also satisfy the compression test in Section 8.8 or the inclined compression test in Annex A1. Table 2Tolerances mm in. 1. Overall vertical dimensions: Design thickness 32 mm 1.
39、2598 in. or less 0, +3 0.1181 Design thickness over 32 mm 1.2598 in. 0, +6 0.2362 2. Overall horizontal dimensions: For measurements 914 mm 35.9842 in. or less 0, +6 0.2362 For measurements greater than 914 mm 35.9842 in. 0, +12 0.4724 3. Thickness of individual layers of elastomer (laminated bearin
40、gs only) at any point within the bearing 3 mm 0.1181 4. Variation from a plane parallel to the theoretical surface (as determined by measurements at the edge of the bearings): Top Slope relative to the bottom of no more than 0.005 radians Sides 6 0.2362 5. Position of exposed connection members 3 0.
41、1181 6. Edge cover of embedded laminates of connection members 0, +3 0.1181 7. Size of holes, slots, or inserts 3 0.1181 8. Position of holes, slots, or inserts 3 0.1181 2016 by the American Association of State Highway and Transportation Officials. All rights reserved. Duplication is a violation of
42、 applicable law.TS-4e M 251-5 AASHTO 7. MARKING 7.1. Each elastomeric bearing shall be marked in indelible ink or flexible paint. The marking shall consist of the order number, lot number, bearing identification number, and elastomer type and grade. Unless otherwise specified in the contract documen
43、ts, the marking shall be on a face that is visible after the bridge is erected. 8. BEARING TESTING AND ACCEPTANCE CRITERIA 8.1. All test apparatus used to determine conformance with these specifications shall be calibrated annually in accordance with ASTM E4. 8.2. Sampling, testing, and acceptance c
44、onsideration will be made on a lot basis. A lot of bearings shall be considered to be a group of 100 or fewer bearings that are manufactured in a reasonably continuous manner from the same batch of elastomer, cured under the same conditions, and are all the same size and type (plain, fabric-laminate
45、d, or steel-laminated). A lot may include 100 or fewer fabric-laminated bearings of different plan size if cut from a large sheet or sheets meeting these requirements. 8.3. The manufacturer shall designate the bearings in each lot and certify that each of the bearings in the lot was manufactured in
46、a reasonably continuous manner from the same batch of elastomer, and cured under the same conditions. In addition, the manufacturer shall certify that each bearing in the lot satisfies the requirements of the design specification and meets the dimensional tolerances of Section 6 of this specificatio
47、n. 8.4. The dimensions of each bearing shall be checked. If any dimension is outside the limits listed in Section 6 of this specification, the lot shall be rejected. 8.5. The purchaser shall select sample bearings from the lot for testing in accordance with this specification. Sampling rate shall be
48、 as follows: Plain BearingsTwo full-size bearings per lot. Laminated BearingsOne full-size bearing per every ten per lot, or a minimum of two bearings. 8.6. Elastomer taken from the sampled bearings shall be tested for conformance with the requirements of Sections 4.1 through 4.1.3 of this specifica
49、tion. If the sampled elastomer fails to meet any of these requirements, the lot shall be rejected. 8.7. Tests may be performed by the manufacturer, by the purchasing agency, or by an outside independent laboratory subject to the approval of the purchaser. If testing is performed by the manufacturer or an independent laboratory, certified test results shall be pr
