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1、INTERNATIONAL STANDARD IS0 6446 First edition 1994-l O-l 5 Rubber products - Bridge bearings - Specification for rubber materials Prod in these cases, the test con- ditions and limits vary with rubber type. Those tests relating to tear strength and resistance to creep are optional and may be added t
2、o the specification as appropriate. It is acknowledged that requirements for the rubber constitute only part of a specification for elastomeric bridge bearings. A complete specification will include statements on the characteristics and quality of reinforcement in laminated bearings and on sampling
3、and frequency of testing as well as load/deflection tests conducted on the complete bearing. Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/23/2007 21:30:35 MDTNo reproduction or networ
4、king permitted without license from IHS -,-,- INTERNATIONAL STANDARD 0 IS0 IS0 6446:1994(E) Rubber products - Bridge bearings - Specification for rubber materials 1 Scope This International Standard specifies requirements for rubber materials used in elastomeric bridge bearings, which may be of the
5、plain-pad or laminated type. It also specifies methods of test and describes pro- cedures for the preparation of test pieces from fin- ished bearings. This International Standard does not contain aspects relating to design properties and quality control of the complete bearing, except where the comp
6、lete bearing is used as the source of samples and test pieces to determine properties of the rubber material. Dimen- sions and tolerances are therefore not included in this International Standard. 2 Normative references The following standards contain provisions which, through reference in this text
7、, constitute provisions of this International Standard. At the time of publi- cation, the editions indicated were valid. All standards are subject to revision, and parties to agreements based on this International Standard are encouraged to investigate the possibility of applying the most re- cent e
8、ditions of the standards indicated below. Members of IEC and IS0 maintain registers of cur- rently valid International Standards. IS0 34-l :1994, Rubber, vulcanized or thermoplastic - Determination of tear strength - Part 1: Trouser, angle and crescent test pieces. IS0 36: 1993, Rubber, vulcanized o
9、r thermoplastic - Determination of adhesion to textile fabric. IS0 37:1994, Rubber, vulcanized or thermoplastic - Determination of tensile stress-strain properties. IS0 48.1994, Rubber, vulcanized or thermoplastic - Determination of hardness (hardness between 10 IRHD and 700 IRHD). IS0 188:1982, Rub
10、ber, vulcanized - Accelerated ageing or heat-resistance tests. IS0 471:-l , Rubber - Times, temperatures and hu- midities for conditioning and testing. IS0 812:1991, Rubber, vulcanized - Determination of low-temperature brittleness. IS0 813:1986, Rubber, vulcanized - Determination of adhesion to met
11、al - One-plate method. IS0 815:1991, Rubber, vulcanized or thermoplastic - Determination of compression set at ambient, ele- vated or low temperatures. IS0 143 l-l : 1989, Rubber, vulcanized or thermoplastic - Resistance to ozone cracking - Part 7: Static strain test. IS0 1827:1991, Rubber, vulcaniz
12、ed or thermoplastic - Determination of modulus in shear or adhesion to rigid plates - Quadruple shear method. IS0 4661-l : 1993, Rubber, vulcanized or thermoplastic - Preparation of samples and test pieces - Part 7: Physical tests. IS0 80 13: 1988, Rubber, vulcanized - Determination of creep in comp
13、ression or shear. 3 Definitions For the purposes of this International Standard, the following definitions apply. 1) To be published. (Revision of IS0 471 :I983 and IS0 l bl a shear modulus or hardness requirement in ac- cordance with 4.2; cl a grade of low-temperature resistance in accord- ance wit
14、h 4.3.2 and the appropriate test require- ments taken from 6.1.4; d) an ozone-resistance test using one of the two test ozone concentrations specified in 6.1.3; e) appropriate quality control requirements for the specified rubber polymer and hardness range in accordance with 6.2; f) the source of te
15、st pieces, using the procedure specified in clause 5. In addition, one of the adhesion tests specified in 6.1.5 shall be included in any specification applicable to laminated bearings. One or more of the optional tests (6.3) for the deter- mination of tear strength and resistance to creep may be inc
16、luded in the specification as appropriate. Test methods, test conditions and limits shall be as specified in this International Standard. Table 1 - Specification for performance properties Property Unit Requirement Permitted overall hardness range IRHD 45 to 75 Shear modulusI) As specified (For tole
17、rance, see table 3) 3r Nominal hardness*) IRHD 50, 60, 70 Permissible tolerance on specified nominal hardness IRHD +5 3zone resistance 25 pphm or 50 pphm ozone, 20 % elongation, 96 h at 40 “C No cracking Low-temperature brittleness Grades 3, 4, 5 only, at temperature specified in table2 No failures
18、Low-temperature hardness Grades 2 to 5 only, after 22 h at temperature specified in table2, maximum increase IRHD 15 1) See 4.2.1. 2) See 4.2.2. Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resa
19、le, 04/23/2007 21:30:35 MDTNo reproduction or networking permitted without license from IHS -,-,- IS0 6446:1994(E) Q IS0 Table 2 - Low-temperature test conditions I 1 Grade Test parameter 1 2 3 4 5 Low-temperature brittleness test temperature, “C N/A ) N/A ) - 25 - 25 -40 Low-temperature hardness te
20、st temperature, “C N/A ) - 10 - 25 - 25 -40 I 1) N/A = not applicable. I Table 3 - Specification for quality control properties Property Unit Requirements for CR NR Overall hardness range IRHD 45 to 75 45 to 75 Tolerance on specified nominal shear modulus MPa + 15% + 15% Tensile strength, min. MPa 1
21、3 15.5 Elongation at break, min. 45 IRHD to 55 IRHD % 400 450 56 IRHD to 65 IRHD % 400 400 66 IRHD to 75 IRHD % 300 300 Compression set, after 22 h at 70 “C, max. % 20 30 Accelerated-ageing resistance Ageing time h 70 168 Ageing temperature “C 100 70 Maximum change from unaged values - hardness IRHD
22、 +15 -3 f 10 - tensile strength % -15 -15 - elongation at break ) % - 40 -20 1) As percentage of unaged value. 6 Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/23/2007 21:30:35 MDTNo re
23、production or networking permitted without license from IHS -,-,- Q IS0 IS0 6446:1994(E) Assessment A.1 Principle Annex A (normative) of adhesion in laminated bridge bearings A portion of a laminated bridge bearing is subjected to a shear deflection in excess of the maximum de- sign deflection, and
24、the rubber and bond are exam- ined for signs of breakdown or separation. The test is sometimes known as the “shear-break” test. A.2 Test pieces Two test pieces each containing no fewer than three layers of rubber shall be cut from the finished bearing. Depending on the thickness of the bearing, the
25、di- mensions of each test piece shall be not less than 50mm x 100 mm, and not more than 100 mm x 200 mm. Two opposite ends of each test piece shall be bevelled to an angle of 45”. A.3 Procedure Between the two test pieces, insert a central loading plate and place the assembly between two suitable mo
26、unting supports (see figureA.l). The loading plate and mounting supports shall be appropriately de- signed to prevent slippage of the test pieces during the test. Apply a vertical (compressive) force Fv equivalent to a compressive stress of 4 MPa. Then gradually apply a horizontal (shear) force F,.,
27、 to the central loading plate until the specified shear stress or deflection is reached. Examine the test pieces for evidence of cracking or peeling both in the strained and unstrained state. NOTE 12 The applied maximum shear stress will depend on the nature of the rubber and on the construction of
28、the bearing. For steel-laminated bearings containing chloroprene rubber materials in the hardness range 56 IRHD to 65 IRHD, a shear stress of 7 MPa is considered suitable for this test. A.4 Expression of results If neither test piece shows evidence of peeling or separation at or near the interface b
29、etween the rubber and reinforcing layers, the bearing shall be concluded to have satisfactory adhesion. F, (constant) Dimensions In millimetres h.50 Figure A.1 - Shear-break test piece and test Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=N
30、ASA Technical Standards 1/9972545001 Not for Resale, 04/23/2007 21:30:35 MDTNo reproduction or networking permitted without license from IHS -,-,- IS0 6446:1994(E) Annex B (informative) Alternative rubber materials B.l Rubber materials based on the following rubber polymers are in limited use in bri
31、dge bearings in vari- ous parts of the world: Terpolymer of ethylene, propylene and a diene with the residual unsaturated portion of the diene in the side chain (EPDM) Isobutene-isoprene copolymer (butyl-rubber - IIR) Chloro-isobutene-isoprene (chlorobutyl rubber - CIIR) B.2 Tentative quality contro
32、l requirements for rub- ber materials based on EPDM, Ill? and CIIR are given in table B.l. These values relate to tests carried out on test pieces specifically moulded for test purposes and not on test pieces cut from bearings. Table B.l - Tentative quality control requirements for alternative rubbe
33、r polymers Property Unit Requirements for EPDM IIR CIIR Hardness range IRHD 60 to 75 55 to 65 55 to 65 Tolerance on specified nominal shear modulus MPa * 15% max. change from unaged values after 70 h at 100 “C - hardness IRHD + 10 f IO + 10 - tensile strength % -15 - 25 - 15 - elongation at break )
34、o/o -40 - 25 - 25 1) As percentage of unaged value. 8 Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/23/2007 21:30:35 MDTNo reproduction or networking permitted without license from IHS
35、 -,-,- IS0 6446:1994(E) Q IS0 ICS 83.140.00; 93.040.00 Descriptors: rubber, rubber products, bridges, supports, speclflcations, materials speciftcatlons, tests. Price based on 8 pases Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/23/2007 21:30:35 MDTNo reproduction or networking permitted without license from IHS -,-,-