Section 564 — Bearing Devices

Description

564.01This work consists of providing and installing bridge bearing devices.

Material

564.02Conform to the following Subsections: Bearings 717.09 Bolts and nuts 717.01(d) Galvaniz ed coatings 717.07 Non-shrink grout 701.04(b)(1)

Construction Requirements

564.03General. Provide elastomeric, rocker, roller, sliding plate, and disc bearing devices.

(a)Drawings. Submit drawings according to Subs ection 104.06 and S ection 18 of the AASHTO, LRFD Bridge Construction Specifications . Show details of bearings including material proposed for use. Do not start fabrication until drawings are approved.

(b)Fabrication. Fabricate bearings according to S ection 18 of AASHTO, LRFD Bridge Construction Specifications . Finish bearing components surfaces in contact with each other or in contact with concrete according to Subs ection 555.07(e) . Preassemble bearing assemblies and check for proper completeness and geometry. Galvanize steel bearing components and anchor bolts. Do not galvanize stainless steel bearing components or anchor bolts. Packaging, handling, and storing material. Clearly identify each bearing component and mark on its top the location and orientation in the structure before shipping. Securely bolt, strap, or otherwise fasten bearings to prevent relative movement. Package bearings to prevent damage during shipping, handling, or storing. Do not dismantle bearing assemblies on site unless necessary for inspection or installation. Dismantle under the direct supervision or approval of the manufacturer. Provide a listing of individual bearing numbers. Store bearing devices to prevent damage from weather or other hazards.

(c)Construction and installation. Clean bearings of deleterious material. Install and set bearings to the dimensions shown in the plans or according to the manufacturer ’s recommendations. Adjust bearings according to the manufacturer’s recommendations to compensate for installation temperature and future movements. 562 Set bearings level, at the elevation, and position shown in the plans. Provide full and even bearing on external bearing contact surf aces. Notify the CO if bearing surfaces are at improper elevations, not level, or if bearings cannot be set properly. Submit a written proposal to modify the installation. Bed metallic bearing assemblies on concrete with an approved filler or fabric materi al when not embedded in concrete. Set elastomeric bearing pads directly on properly prepared concrete surfaces without bedding material. Machine bearing surfaces seated directly on steel to provide a level and planar bearing surface.

564.04Elastomeric Bearings. Fabricate, comply with testing and acceptance criteria, and mark elastomeric bearings according to AASHTO M 251. Test and accept bearings specified by hardness and designed according to Method A of AASHTO, LRFD Bridge Design Specifications accordin g to Section 8.8.4 of AASHTO M 251. Place bearings on a level surface. Correct misalignments in the support to form a level surface. Do not weld steel girders or base plates to the exterior plates of the bearing unless there is more than 1½ inches of steel between the weld and elastomer. Do not expose the elastomer or elastomer bond to instantaneous temperatures greater than 400 °F. Do not design or fabricate elastomeric bearings with holes.

564.05Rocker, Roller, and Sliding Plate Bearings. Fabricate pins, rollers, and rockers according to Subs ection 555.10. Remove burrs, rough and sharp edges, and other flaws. Stress relieve rocker, roller, and other bearings that are built up by welding sections of plate together before boring, straightening, or final machining. Thoroughly coat contact surfaces with oil and graphite before placing roller bearings. Install rocker, roller, and sliding bearings vertically at the specified mean temperature after release of falsework and after shortening due to prestressing forces. Account for variations from mean temperature of the supported span at time of installation and other anticipated changes in length of the supported span. Ensure the superstructure has full and free movement at movable bearings. Position roller bearings so their axes of rotation align and coincide with the axis of rotation of the superstructure.

564.06Disc Bearings. Use structural steel plates conforming to AASHTO M 270, Grade 50. Equip disc bearings with a shear rest riction mechanism to prevent movement of the disc. Use disc bearings produced by the same manufacturer. For guided bearings, use either a guide bar or keyway system to restrict transverse movement. Face the sliding surfaces of the guide bar or keyway syste ms with either PTFE sheets or stainless steel. Provide polyether urethane rotational elements molded as a single piece. Design the disc bearings for the loads and movements shown in the plans according to AASHTO, LRFD Bridge Design Specifications . Install according to the manufacturer’s recommendations. Submit manufacturer’s test results to the CO certifying that the completed bearings and their components comply with the proof load test and sliding coefficient of friction test, according to S ubsection 18.3.4 of AASHTO, LRFD Bridge Construction Specifications . Bearings represented by test specimens passing the requirements are approved for use in the structure subject to on -site inspection for visible defects. Bearing devices showing visual defects will be r ejected. Visual defects include extruded or deformed elastomer or PTFE, damaged seals or rings, and cracked steel.

564.07Masonry, Sole, and Shim Plates for Bearings. Provide metal plates conforming to AASHTO M 270, Grade 36. Fabricate and finish steel according to Subs ection 555.07. Form holes in bearing plates by drilling, punching, or controlled oxygen cutting. Remove burrs by grinding. Set bearing plates in a level position and provide a uniform bearing over the bearing contact area. If plates are embedded in concrete, make provisions to keep them in correct position as the concrete is placed.

564.08Polytetrafluoroethylene Surfaces for Bearings. Provide PTFE material that is factory -bonded, mechanically connected, or recessed into the backup material. Bond or mechanically attach the fabric containing PTFE fibers to a rigid substrate. Use a fabric that can carry unit loads of 10,000 pounds per square inch without cold flow. Use a fabric-substrate bond that can withstand a shear force equal to 10 percent of the perpendicular or normal application loading plus other bearing shear forces without delamination. Use approved test methods and procedures according to Section 18 of AASHTO, LRFD Bridge Construction Specifications . Perform at least one material test on the material used in the sliding surface for each lot of bearings. If required by the contract, test complete bearings for complete bearing friction. If the test facility does not allow testing of completed bearings, manufacture extra bearings and prep are samples of at least 100 -kip capacity at normal working stresses by sectioning the bearing. Measure the coefficient of friction between two mating surfaces. Submit test results showing the static and dynamic coefficients of friction meet the requirements for the design coefficient of friction specified in the contract or by the manufacturer for approved material.

564.09Anchor Bolts. Provide threaded anchor bolts. Adjust bolt locations for superstructure temperature and anticipated lengthening of bottom chord or bottom flange due to dead load after setting as required. Do not restrict free movement of the superstructure at movable bearings. Preset anchor bolts before concrete placement or install anchor bolts in drilled holes after concrete placement. Dr ill holes 1 inch in diameter greater than the bolt if non -shrink cement grout is used to secure the bolts. Follow the adhesive manufacturer’s recommendations for hole diameter if an approved chemical adhesive is used to secure the bolts.

564.10Bedding of Masonry Plates. Clean the contact surfaces of the concrete and steel before placing the bedding material and installing bearings or masonry plates. If bedding is specified, place filler or fabric as bedding material under masonry plates and install it to provide full bearing on contact areas. If bedding material is not specified, comply with Subs ection 18.10.2 of AASHTO, LRFD Bridge Construction Specifications as directed.

564.11Acceptance. Material for b earing devices will be evaluated under Subsections 106.02 and 106.03. 564 Submit a production certification with each shipment of bearing devices. Bearing device installation will be evaluated under Subsections 106.02 and 106.04.

Measurement

564.12Measure the Section 564 pay items listed in the bid schedule according to Subsection 109.02 and the follow ing as applicable: Do not measure bearing devices for prefabricated steel bridges and fiber -reinforced polymer bridges.

Payment

564.13The accepted quantities will be paid at the contract price per unit of measurement f or the Section 564 pay items listed in the bid schedule. Payment will be full compensation for the work prescribed in this Section. See Subsection 109.05 .