5-138 523.051 Protective Coating Steel parts of bearings shall have protective coating applied to the areas described within this section in accordance with S ection 506, Shop Applied Protective Coating- Steel. Masonry plates shall, at the Contractor’s option, be galvanized or metalized. The masonry plates shall be top coate d to match the coating of the superstructure beams when beams are coated. Portions of bearings between the masonry plate and sole plate t hat will be exposed after installation shall, at the Contractor’s option, be galvanized o r metalized. Steel between the masonry and sole plates shall be top coated to match the color of the superstructure beams when the adjacent superstructure beams are coated. Stainless st eel and /or machined surfaces with a roughness height of 125 micro-inches or smoother shall n ot be coated. Machined surface finishes with a roughness height of 125 micro-inches or smoother, except stainless steel, shall be lubricated wit h a non-corrosive, waterproof, hi gh pressure lubricant having a temperature range of -30 oF to 150 oF, National Lubrication and Grease Institute number not lower than 2 and an OK load of not less than 20 lbs., as measur ed by the requirements of ASTM D2509. Metal surfaces designed for sliding in contact with Teflon (PTFE) coated surfaces shall not be lubricated. Sole plates shall have the same finish as the adjacent structur al steel. When adjacent structural steel is coated, the sole plate shall be galvanized/ or metalized, at the option of the contractor. Sole plates shall be top coated to match the color of the superstructure beams. When the adjacent structural steel is bare and uncoated, the so le plate shall be bare and uncoated. When the adjacent beams are concrete, the sole plates shall be galvanized. Areas to be field welded shall not be c oated prior to welding; they s hall be touched up after welding. Anchor rods shall be galvanized. When anchor rods are designate d to secure bare unpainted steel, a dielectric coating (epoxy or bituminous type coatings are acceptable) shall be applied to the anchor rod and/or adjacent steel to prevent c ontact between galvanized surfaces and bare unpainted steel. When bearings, or portions o f bearings, are painted to match adjacent structural steel, the anchor rods shall also be painted.
523.06 Fabrication Tolerances Fabrication tolerances for all b earings shall comply with
Section 18.1 of AASHTO, LRFD Bri dge Construction Specifications (Table 18.1.4.2-1) unless otherwise noted on the Plans or in this Section 523, Bea rings. 523.061 Material Friction Test The coefficient of friction (‘c of’) between the two mating surfaces shall be measured. Tests shall be made either o n samples taken from the same batch of materials as those used in the prototype bearings or the tests may, at the manufacturer’s option, be conducted on finished bearings. Only new materials shall be used; material that has been previously tested shall not be used. The surfaces shall be thoroughly cleaned with a degreasing solv ent. No lubrication, other than that specified for t he prototype bearings, shall be used. The mating surfaces for 5-139 the test pieces shall have a common area no less than the small er of the bearing area or 7.0 square inches. The test piece shall be loaded in compression to a stress corre sponding to their maximum service dead load plus live load, which shall be held f or one hour prior to, and throughout the duration of, the sliding test. At least 100 cycl es of sliding, each consisting of at least 1.0 inch of movement, shall then be applied at a tempe rature of 68 oF ± 2 oF. The uniform sliding speed shall be 2.5 inches per minute. The breakaway ‘cof’ shall be c omputed for each direction of eac h cycle and its mean and standard deviation shall be computed for the sixth through twelfth cycles. The initial static breakaway ‘cof’ for the f irst cycle shall not exceed twi ce the design ‘cof’. The maximum ‘cof’ for all subsequent cycles shall not exceed the de sign ‘cof’. Failure of a single sample shall result in rejection of the entire lot. Following the 100 cycles of testing, the breakaway ‘cof’ shall be determined again and shall not exceed the initial value. The bearing or specimen sha ll show no appreciable sign of wear, bond failure, or other defects.
523.07 Inspection The Contractor shall notify the Fabrication Engineer at least 10 days
in advance of the start of fabrication so that inspection of th e work can be provided by the Department. All work will be subject to inspection by the Fabr ication Engineer. Quality Control (QC) is the responsibility of the Contractor. The Quality Control Inspector (QCI) shall inspect all aspects of the work and shall supervise all testing. The QCI shall record measurements and test results in a Job Control Rec ord (JCR). The QCI shall reject materials and workmanship that do not meet contract requ irements. The Contractor may perform testing in addition to the minimum required. The r esults of all measurements and testing shall be made available to the Quality Assurance In spector (QAI). Quality Assurance (QA) is the prerogative of the Fabrication En gineer. The QAI will ensure that the Contractor’s QC is performing properly, verify documentation, periodically inspect workmanship and witness testing. QA testing deemed nece ssary by the Fabrication Engineer in addition to the minimum testing requirements shall be scheduled to minimize interference with the production schedule.
523.08 Certification The Contractor shall furnish a materials certification letter in
accordance with Division 700.
523.09 Installation of Bearings Bearings shall be placed upon bridge seats that are
properly finished. Bridge seat elevations shall be within + ¼ inch of the elevation shown on the Plans and the differential elevation between any two adjace nt bearing areas shall not exceed + ⅜ inch. When the bearings are to be set directly on the concrete bridge seats, as indicated on the Plans, the bridge seats shall be dressed 1 inch larger all arou nd than the bottom member of 5-140 the bearing and to the exact elevations shown on the Plans or a s determined by the Resident. If dressed areas are lower tha n the surface of the surrounding bridge seat, a channel 2 inches wide and with a minimum slope of 4 percent, shall be cut to the edge of the bridge seat for drainage. Masonry plates shall be set level in their exact position and s hall have a full and even bearing upon the masonry. They shall be placed on a preformed pad, the same size and shape as the masonry plate with holes to match the masonry plat e. 523.091 Anchor Rods The contractor shall drill the holes and s et the anchor rods with a chemical or cementitious Anchoring Material from the Department Qualified Products List. The Anchoring Material shall completely fill the holes. In pla ce anchor rods shall be capable of developing unconfined pullout strength of 30 kips an d 70 kips for M24 and M36, 1 inch and 1-½ inch anchor bolts, respectively. 523.092 Grout Pads When the bearings are to be set on a grout pad, the grout shall be a non-shrink cementitious grout from the Grout Materials list of the Department Qualified Products List. The grout shall have a minimum design compressi ve strength of 6,000 psi at 28 days, unless otherwise specified in the Contract.” The grout shall be well bonded to the adjacent concrete and sha ll be placed under pressure to ensure that all anchor holes and the entire area un der the masonry plate is free of voids. 523.093 Sliding Surfaces The sliding surfaces of bearings shal l be installed level. Special care shall be exercised at all times to ensure protecti on of the stainless steel and the PTFE surfaces from coming in contact with any foreign matter. At no time shall any forms, debris, or other material interfere with the free action of the bearing assemblies. When bronze or copper-alloy bearing and expansion plates are us ed, the sliding surfaces or the steel in contact with t he bearing and expansion plates s hall be recoated immediately prior to installation with a lubricant recommended by the manuf acturer of the bronze or copper-alloy plates. 523.094 Final Adjustment Bearings shall not be connected in pl ace until the deck is in place. Final adjustment of the bearings for temperature shall be made after the deck is in place. Connecting of the bearing sol e plate to the girder flan ge shall be done only after all adjustments have been made. Sliding expansion bearings shall be set so that slotted holes i n the sole plate will be centered on the anchor bolts, and rocker bearing assemblies sha ll be set so as to be plumb at 45 ºF. When determining temperature adjustments for bearings, the difference between the steel temperature (not the ambient temperature) and 45 ºF shall be used. 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.