Bearings designed as a single unit shall be built as a single unit. 280 Each reinforced bearing shall be marked with indelible ink or flexible paint. The marking shall consist of the orientation, the order number, lot number, bearing identification number, and elastomer type and grade number. Unless otherwise specified, the marking shall be on a face that is visible after erection of the bridge. Where load plates are shown on the plans, the bearing shall be vulcanized to the steel load plate during the primary molding process. (d) Appearance and Dimensions The edges of the embedded steel laminates, including around holes, shall be 290 covered with 1/8 to 1/4 in. of elastomer. All other dimension tolerances shall be in accordance with AASHTO M 251.
The mechanical properties of the materials and of the finished bearing shall be in accordance with the AASHTO LRFD Bridge Construction Specifications, Article 18.2.5, and AASHTO M 251, with the exception that the tables in 915.04(b)1 shall be used.
shall not exceed 7% at 800 psi average unit pressure or at the design dead load plus live load pressure if shown on the plans.
for 55 durometer, table A compounds; or 75 psi for 55 durometer, table B compounds at 25% strain of the total effective rubber thickness af ter an extended four-day ambient temperature of -20°F. 310
elastomeric bearings. The limits of the following shall be shown on the certification: 915.04 1123 Test ASTM or INDOT Standard Specifications Ultimate Tensile Strength D412 Ultimate Elongation D412 Hardness (Durometer) D2240 Tensile Strength and Elongation on Oven-aged Material D573 and D412 Hardness on Oven-aged Material D573 and D2240 Compression Set D395, Method B Ozone Resistance D1149 Adhesion D429, Method B Brittleness D746, Procedure 9.1.2 Compressive Strain 915.04(e)1 Shear Resistance 915.04(e)2
When steel components are incorporated into elastomeric bearings, a mill certification, galvanization certification, if applicable, and a Buy America Certification in accordance with 106.01(c) will be required. In addition, one bearing pad from each type to be furnished for the structure will 320 be required for laboratory testing. A type of bearing is defined by the length, width, and thickness of elastomer, and the number and thickness of internal shims. Bearings that differ by the dimensions of load plates vulcanized to similar elastomeric pads will also be considered different types. The material may be sampled prior to shipment to the project, provided suitable arrangements can be made through the Department’s Division of Materials and Tests. Materials not previously sampled and tested shall be sampled for testing after delivery to the project site. Samples shall be furnished for testing at least 30 days before date of use. Passing test results will be required prior to using the material. 330
915.05Bearing Assemblies with Polytetrafluoroethylene, PTFE, Sliding Surfaces
A copy of the manufacturer’s design manual shall be submitted for approval when directed. All steel components shall be in acco rdance with ASTM A709, grade 36 unless otherwise shown on the plans. Where these assemblies are used in conjunction with weathering steel, the steel components shall be in accordance with ASTM A709, grade 50W. Stainless steel mating su rfaces shall be 14 gauge minimum ASTM A240, Type 304 sheets with a maximum surface roughness of 20 Rms. 340 The PTFE shall be 100% virgin unfilled polymer or 15% glass filled and etched on the bonding side. The properties of the PTFE shall be in accordance with the following: 915.05 1124 Requirement Test Method Value Tensile Strength, minimum ASTM D638 2,500 psi Elongation, %, minimum ASTM D638 200 Specific Gravity ASTM D792 2.1 to 2.3
PTFE, where required, shall be virgin ma terial, etched on the bonding face and in accordance with ASTM D 4894. The PTFE sh all be bonded to grit blasted steel in accordance with Federal Spec ification MMM-A-134, Type 1. The elastomeric pad shall be vulcanized to the steel load plate during the primary molding process. The 350 stainless steel sliding plate shall be s eal welded to the steel load plate. All steel surfaces exposed to the environment shall be zinc metalized and shall be 7 mils thick in accordance with SSPC-CS 23.00 or painted in accordance with
619.09(a). The finish coat for painted steel shall be in accordance with 909.02(d). The
color shall be in accordance with SAE-AMS-STD-595, color No. 20045. A Type B certification in accordance with 916 shall be provided for the bearing assemblies. The limits of the above shall be shown on the certification. 360