5-141 Nuts on anchor rods shall be brought in contact with the masonr y plate or sole plate as shown on the Plans. Threads on anchor rods shall be upset with a punch to prevent easy removal of the nuts. When anchor rods extend through slotted h oles in a sole plate, the lower of double nuts shall be l eft loose, bring to contact and loosen approximately ¼ turn, to allow movement of the sole plate. STEEL BEARINGS
523.10 Steel Bearings Structural steel bearings- rocker type and sliding plate type-
shall be fabricated in accordance with the dimensions and finis hes shown on the Plans, Standard Details and the requirements of Section 504, Structura l Steel. Bearings, base plates and other contact surfaces shall be finis hed to the following tolerances: Surface Roughness Requirements Steel slabs ANSI 2000 micro-inches Bearing sole plates ANSI 1000 micro-inches Milled ends to compression members, milled or ground ends of stiffeners or rockers ANSI 500 micro inches Bridge rockers and rollers ANSI 250 micro-inches Sliding bearings ANSI 125 micro-inches Pins and pin holes ANSI 125 micro-inches Bearing mating surfaces (includi ng steel to steel, or steel to bronze and steel to elastomeric material) shall have a minimum of 90% contact area. Flatness (the permissible variation from a true plane) shall be a maximum of 1/32 inch.
523.11 Materials Materials shall conform to Section 523.02, Ma terials.
ELASTOMERIC BEARINGS
523.20 Description Two types of bearings are applicable for th e following Sections:
Laminated Elastomeric Bearings, which shall consist of layers o f elastomer laminated to steel plates; and Plain Elastomeric Bearings, which shall consi st of a single layer of elastomer.
523.21 Materials Materials shall conform to Section 523.02, Ma terials.
If the elastomer material is specified by its shear modulus on the Plans, the measured shear modulus value shall lie within the specified range. When the elastomer material is specified by shear modulus, the Contractor shall supply a consi stent value of hardness for the purposes of defining limits for the tests of Table A and B in Section 711.11. Laminated Elastomeric bearings shall have a Shore A Durometer h ardness of 50 or 60. Plain Elastomeric bearings shall have a Shore A Durometer hardn ess of between 50 and 70. 5-142 Shear modulus tests shall be carried out using the apparatus an d procedure described in Annex A of the ASTM D4014 specifications.
523.22 Fabrication All components of Laminated Elastomeric Bea rings shall be molded
as an integral unit. Plain Elastomeric Bearings may be molded individually, cut from previously molded slabs, or ext ruded and cut to length. Cut ed ges shall have an ANSI 250 mils finish. Steel laminates shall be abrasive blast cleaned t o an SSPC SP-6 and protected from contamination. The Fabricator must be on the Departments Qualified Supplier List.
523.23 Testing The following testing shall be performed prior to delivery of the
bearings:
1.Ambient Temperature Tests on the Elastomer (This test is re quired for each elastomer formulation) The bond to the reinforcement shall develop a minimum peel stre ngth of 40 pounds/inch. Peel strength tests shall be performed in accordance with ASTM D429, Method B.
2.Low-Temperature Test on the Elastomer (This test is require d for each elastomer formulation) Low-temperature tests shall be performed in accordance with the requirements of Section 711.11; the compound shall satisfy all criteria for its grade. The manufacturer may choose to provide certificates from low-temperature crystalliza tion tests performed on identical material, within the last year, for Grade 3 to Grade 5 material.
3.Visual Inspection of the Finished Bearing Each laminated be aring shall be inspected for compliance with dimensional tolerances and for overall qual ity of manufacture. In steel reinforced bearings, the edges of the steel shall be protected everywhere from corrosion.
4.Short-Duration Compression Tests on Bearings Each laminated bearing shall be loaded in compression to 150% of t he Bearing Design Load. The load shall be maintained for 5 minutes and released. The same load shall be reapplied a nd maintained for a second period of 5 minutes. The bearing shall be examined visually du ring the second loading. If the load drops below the required value during either applicati on, the test shall be performed again. The bearing shall be rejected if: The bulging pattern suggests laminate parallelism outside of th e specified tolerance, A layer thickness is outside the specified tolerances, A poor laminate bond exists, or Three or more separate surface cracks greater than 0.08 inch wi de and 0.08 inch deep exists.
Source: Maine Standard Specifications for Road and Bridge Construction, 2020 Edition. Pages 433–434 of 817.