2019-02-11-minutes-public-works-study-session

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7.0 FINISH 7.1 Blast Cleaning Exposed surfaces of structural steel to be wipe cleaned in accordance with the Steel Structures Painting Council (SSPC), Surface Preparation Specification No. 1, latest edition, (SSPC-SP1), Wipe -Off Clean. Exposed surfaces of steel shall be defined as those surfaces seen from the deck or from the outside and bottom of the structure. 8.0 BEARINGS 8.1 Bearing Plates Bearing plates shall be used under the stringers at both ends of the bridge and shall be designed to support the anticipated reactions and thermal movement. Bearing plate material shall be ASTM A572 Grade 50 or A588 for painted, metalized and galvanized bridges or ASTM A588 for weathering steel bridges. The Bridge Manufacturer shall design the bearing plates such that one end of the bridge is fixed and the other end allows for expansion. All bearing plates shall have a minimum of two holes to receive anchor rods (one on each side of the stringer). For the expansion base plates, holes shall be slotted with a minimum of 3" in the slot to allow for expansion and contraction. All bearing plates shall be shipped loose for field installation by others; field welded to the stringers by an AWS D1.5 certified welder. If the longitudinal grade of the bridge is equal to or greater than 1.5%, then the bearing plates shall be beveled across their width in order to provide a level bearing condition on the elastomeric pads. 8.2 Elastomeric Pads The Bearing plates will placed on top of elastomeric pads. Elastomeric pads shall be 60-Durometer Neoprene and are to be used only as leveling pads and do not meet AASHTO LRFD design criteria. Elastomeric Pads shall be a minimum 1/2" thick. 9.0 PRECAST CONCRETE SILLS & ANCHOR PLATES Precast concrete sills shall be designed and supplied by the Bridge Manufacturer. The precast concrete sills shall be cast by a plant which carries the National Precast Concrete Association (NPCA) certification. The precast concrete sill(s) shall be at a minimum 1'-6" deep by 2'-6" wide by 16' long. The precast concrete sill shall be reinforced with stirrups and longitudinal reinforcing bars (minimum Grade 40), and have a minimum concrete strength of 4000psi. A 2" minimum concrete cover shall be maintained for all reinforcing. Lifting lugs shall be installed to aid in the unloading and placement of the precast concrete sills. On top of the precast concrete sill, an ASTM A588 plate (112" thick by 6" wide and running the entire length of the sill) shall be embedded into the concrete with shear studs. This top plate will be used to attach the anchor plates via field welding by the Contractor. Corner embed angles shall be installed in the sills to allow for the field welding together of the multiple sections prior to the installation of the full bridge superstructure. Anchor plates will consist of two 1.25" diameter by 5" long fully -threaded zinc plated rods welded to the surface and spaced to match the hole spacing in the bridge bearing plates and elastomeric pads. Two nuts and one washer (all galvanized) shall be supplied with each rod. 10.0 BACK WALLS The back wall system shall be comprised of two pieces of Big R Bridge sheet piling extending 3'-4" in total height. The sheet piling shall be of 10 gauge material. The length of the top piece of sheet pile shall be equal to the bridge width plus 5 feet. The length of the bottom piece of sheet pile shall be equal to the bridge width plus 10 feet. Back walls shall be designed to support the backfill and applied traffic loads. The finish of the sheet pile shall be as follows: Galvanized.