00582.00 570 Section 00582 - Bridge Bearings
Description
00582.00Scope - This Work consists of furnishing and installing composite bridge bearings,
elastomeric bridge bearings, and rockers and hangers for Bridges as shown, specified, or directed.
00582.02Definitions :
Composite Bearing - Bearing having a rotational element between an upper and a lower unit. This includes Disc Bearings, Fabric Pad Bearings, Pot Bearings and Spherical Bearings.
Disc Bearing - Composite Bearing whose rotational element is comprised of a polyether urethane disc with an upper and lower unit.
Elastomeric Bearing - Bearing consisting of a single layer of elastomer (plain) or of several layers of elastomer alternated with steel plates (reinforced).
Fabric Pad Bearing - Composite Bearing whose rotational element is a preformed fabric pad.
Fixed - Restrained against all horizontal structural movement. Guide Bars - The elements that restrain the lateral movement of a sliding bearing.
Guided - Able to accommodate structural movement in a specified horizontal direction. Nonguided - Able to accommodate structural movement in all horizontal directions. Pot Bearing - Composite Bearing whose rotational element is a piston supported on an elastomeric disc, totally confined within a base pot cylinder.
Spherical Bearing - Composite Bearing whose rotational element consists of an upper plate with a spherical concave bottom surface and a lower plate with a spherical convex top surface.
00582.03Design - Design and fabricate composite bridge bearings according to the latest edition of
the AASHTO LRFD Design Specifications .
Materials
00582.10Materials - Furnish composite bridge bearing Materials meeting the requirements of
Section 02571. Furnish rockers and hangers, constructed entirely of structural steel, according to Section 00560.
00582.20Composite Bearings - Provide only one type of C omposite Bearing from the QPL for each
Bridge , subject to the following requirements:
• Make Composite Bearings, including all plates except distribution plates and masonry plates, removable and replaceable. • Provide rotational elements between upper and lower units to meet the following:
• Upper Unit - The upper unit shall consist of a distribution plate that is perma nently attached to the Superstructure and a sole plate attached to the distribution plate with cap screws. For 00582.25 571 a Guided or Nonguided bearing, a stainless steel sheet shall be welded to the bottom surface of the sole plate.
• Lower Unit - The lower unit shall consist of a masonry plate permanently anchored to the structural support and a base plate attached to the masonry plate with cap screws. A separate masonry plate and base plate are not necessary for F abric Pad Bearings fabricated as outlined in 00582. 27, third paragraph.
• Bearing -to-Base Connection:
• The base pot of a Pot Bearing, the lower bearing plate of a D isc Bearing, or the convex plate of a Spherical Bearing shall be welded to the base plate. • For Guided or N onguided bearings, a polytetrafluoroethylene (PTFE) sheet shall be recessed into and bonded to the top surface of the piston of a Pot Bearing, the upper bearing plate of a D isc Bearing, the top surface of the concave plate of a Spherical Bearing, or a stee l backing plate bonded to the top surface of a fabric pad forming a sliding surface with the stainless steel surface of the sole plate. • For Fixed bearings, the piston of a Pot Bearing, the upper bearing plate of a D isc Bearing, or the concave plate of a Sp herical Bearing shall be welded to the sole plate.
Provide bearings that accommodate the loads, movements, and rotations as shown.
Use schematic drawings, or details of bearings shown, to describe the attachment of the upper unit to the Superstructure, a nd the attachment of the lower unit to the Substructure.
00582.21Disc Bearings - Design Disc Bearings according to the following:
• The shear restriction mechanism shall allow free rotation but prevent any shear being applied to the rotational element. • Each Guided bearing shall resist the total horizontal load at the bent or hinge where it is located.
00582.25Composite Bearings with Polytetrafluoroethylene Sliding Surface:
bonded to for all C omposite Bearings. Bond PTFE to the steel substrate sufficiently to develop a horizontal force as shown and not less than 10 percent of the vertical design capacity shown, in addition to the shear force developed as a result of the natural bearing friction shear force.
PTFE having a minimum thickness of 1/8 inch. The PTFE shall be recessed 1/16 inch into the spherical element. PTFE fabric minimum thickness shall be 1/16 inch when measured according to ASTM D1777.
completely covers the PTFE surface in all operating positions, plus at least 2 inches more in every direction of possible movement. Provide a spherical stainless steel rotational surface attached to the convex surface of the spherical convex plate of eachS pherical Bearing so that it completely covers the convex surface of the plate.
00582.26 572 00582.26 Guide Bars for Composite Bearings - Provide a sliding surface between the G uide Bars and the guide element made of polished stainless steel against virgin PTFE. The virgin PTFE shall be bonded and mechanically fast ened to the G uide Bars. Provide G uide Bars that:
• Resist the horizontal design forces on the bearing, but not less than 10 percent of the vertical design load of the bearing. • Resist the total horizontal load at the bent or hinge where it is located. Do not include the resistance due to bearing friction as part of the horizontal load capacity of G uided bearings and Fixed bearings. • Are Integral and machined from a solid plate, or attached by welding or with cap screws, or fabricated from a single steel plat e. • Have a space equal to 3/16 inch plus or minus 1/16 inch to the G uided member. • Allow the G uided member to be always within the guides at all points of translation and rotation of the bearing. Avoid guiding the member off the F ixed base or any extension of it where transverse rotation is anticipated.
00582.27Sole, Base, Distribution, and Masonry Plates for Composite Bearings - Make the
bottom surface of sole plates flat and level. Make the top surface flat, and sloped as required to mate with the bot tom surface of the distribution plate.
Use 3/4 inch minimum plates, except sole plates may taper to 5/8 inch at the thinnest edge.
For Fabric Pad Bearings, keeper bars at least 1/4 inch thick shall be fastened to the top surface of the base plate, around the perimeter of the fabric pad, with high -strength cap screws. Provide a gap at all bar ends to allow drainage.
Provide studded anchors or threaded bolts, as shown or specified, to anchor the masonry plates to the supported and supporting members. Locate anchoring devices to avoid conflict with metal reinforcement and prestressing systems.
00582.30Fabrication - Fabricate bearings according to the reviewed Working Drawings and the
Specifications.
Composite Bearings and Elastomeric Bearings.
• Complete details of the anchor layout • Plan and elevation of the bearing showing dimensions and tolerances • Complete details of all components with sections showing all M aterials incorporated into the bearing • All ASTM or other material designations • Vertical and horizontal force capacity • Compressive stresses on all sliding surfaces, and on elastomeric polyether urethane and cotton duck surfaces, at maximum and minimum design loads • Rotational capacity • Translation capacity for Guided and N onguided bearings • Instructions for installation of the bearing
00582.33 573 • The overall dimensions of the bearings • The durometer hardness of the elastomer and the ASTM designation of reinforcing materials, if any • The thicknesses of the components of reinforced bearings and the cover over edges of reinforcements
to 00560.26.
calculations supporting the design for horizontal force capacity, according to 00150.35. Calculations are not required when t he design horizontal capacity is less than, or equal to, 10 percent of the design vertical capacity. A horizontal proof load test report may be submitted instead of engineer's calculations. See 02570.20(b) for test requirements.
00582.31Disc Bearings - Fabricate upper and lower bearing plates as follows:
• Connect the lower bearing plate to base plate by means of a fillet weld around entire perimeter of the lower bearing plate. • For a F ixed bearing, connect upper bearing plate to the sole plate by means of a fillet weld around the entire perimeter of upper bearing plate.
00582.32Fabric Pad Bearings - Fabricate Fabric Pad Bearings according to the following:
Bond the backing plate to the top surface of the fabric pad under controlled conditions and according to the written instructions of the manufacturer of the adhesive system specified by the fabric pad manufacturer.
Finish the surface of steel recess to a s urface roughness of 250 microinches or better, and to Class A flatness:
thick, place an 11 gauge steel shim at mid-depth.
00582.33Pot Bearings - Fabricate Pot Bearings according to the following:
Finish the top and bottom surfaces of the pot cylinder to Class A flatness.
Connect the pot cylinder to the base plate by means of a fi llet weld around the entire perimeter of the pot cylinder.
Finish the top surface to Class A flatness.
00582.34 574 Finish the bottom surface to Class C flatness.
For a F ixed bearing connect the piston to the sole plate by means of a fillet weld around the entire perimeter of the piston.
Recess the upper edge of the elastomeric disc to accommodate the flat brass sealing rings.
Lubricate the di sc with a material compatible with the elastomer.
00582.34Spherical Bearings - Fabricate Spherical Bearings according to the following:
Finish top surface to a roughness of 125 microinches or better, and Class A flatness.
Fabricate the concave radius of the bottom surface to have a positive tolerance not to exceed 0.010 inch according to ANSI Y14.5.
For a F ixed bearing, connect to the sole plate by means of a fillet weld around the entire perimeter of top surfac e of spherical concave plate.
• Solid stainless steel ASTM A240, Type 304 or 304L • Stainless steel weld overlay a minimum of 3/32 inch thick
Fabricate convex radius of the top surface to have a negative tolerance not to exceed 0.010 inch according to ANSI Y14.5. Finish the top surface to a roughness of 20 microinches or better, and other surfaces to a roughness of 250 microinches or better.
Finish the botto m surface to Class B flatness.
Connect to base plate by means of a fillet weld around entire perimeter of bottom surface of spherical convex plate.
00582.35Composite Bearings with Polytetrafluoroethylene Sliding Surfaces:
conditions and according to the written instructions of the manufacturer of the adhesive system specified by the PTFE manufacturer. After completion of the bondi ng operation, the PTFE surface shall be smooth and free of bubbles.
around entire perimeter of stainless steel sheet. Clamp stainless steel sheet down to hav e full contact with the steel substrate during welding. Fabricate so welds do not protrude beyond the sliding surface of the stainless steel.
00582.36Guide Bars for Composite Bearings - Construct Guide Bars parallel to the surface on
which they bear and to other Guide Bars to within a tolerance of plus or minus 1/32 inch for the full length of the bar. 00582.50 575 The tolerance for section dimensions is plus or minus 1/16 inch.
If Guide Bars are welded to the sole plate, w eld before attaching the stainless steel surface.
00582.38Coatings for Steel Bearings - Coat all exposed steel surfaces, except stainless steel,
according to Section 00594.
00582.39Elastomeric Bearings - Fabricate Elastomeric Bearings according to the following:
over 1/2 inch in thickness shall consist of alternate laminations of elastomer and metal.
holes will be allowed except pads 1/2 inch and less in thickness may be sheared.
00582. 40 Shipping and Handling - Protect all bearings from damage during shipment, and keep them dust -free. Protect C omposite Bearings as follows:
• Fully assemble each bearing at the manufacturing plant and deliver to the construction site as a complete unit ready for installation. • Mark centerlines on the sole plate and base plate for checking alignment in the field. • Hold bearings together with removable restraints so the sliding surfaces are not damaged. • Ship and store bearings in lightproof, mo isture -proof and dustproof packages.
Construction
00582.50Installation - Use only one type of bearing on any one Bridge unless shown, specified or
directed otherwise.
• Obtain approval of the bearing assembly proposed for use before constructing the upper portions of the supporting Structure so bearing elevations may be properly determined. • Before constructing bridge bearing seats, inform the Engineer in writing, of the total bearing thickness. • Do not place bridge bearings on concrete bearing areas that are irregular or improperly prepared. • Install bearings level and according to the manufacturer's recommendations, subject to the Specifications. • Install bearings in exact positions, and wit h full and even bearing. • Protect the sliding surfaces of PTFE bearings from contact with concrete or other foreign matter. • To prevent gouging and contamination, install bearing with the stainless steel surface on top of the PTFE interface.
bottom surfaces of the members which will bear on them. Install as follows:
• Set elastomeric bearing pads directly on the concrete pad surface. 00582.80 576 • Provide for a uniform bearing over the entire area of the bearing seat and over the entire area of the Superstructure member in contact with the bearing pad. • Keep pads in correct position during erection of Superstructure members.
assemblies.
Measurement
00582.80Measurement - The quantities of Work performed under this Section will be measured
according to the following:
Bearings and steel -reinforced elastomeric bearing pads will be measured on the unit basis, of bearing devices in place which includes all components from the bearing seat attachment through the Superstructure attachment.
Payment
00582.90Payment - The accepted quantities of bridge bearings will be paid for according to the
following:
bearings and steel -reinforced elastomeric bearing pads will be paid for at the Contract unit price, per each, for the following items:
Pay Item Unit of Measurement
In item (a), the type (disc, fabric pad, pot, spherical) of C omposite Bearing device will be inserted in the blank. In item (b), for steel -reinforced elastomeric bearing pads, the width of bearing pad will be inserted in the first blank, the length of the bearing pad will be inserted in the second blank, and the thickness of the bearing pad will be inserted in the third blank.
Payment will be payment in full for furnishing and placing all Materials, and for furnishing all Equipment , labor, and Incidentals necessary to complete the Work as specified. No separate or additional payment will be made for designing, fabricating, and testing composite bearings or steel -reinforced elastomeric bearing pads .
bearing pads. This item is included in payment of precast prestressed concrete and structural steel members.