581Pot Bearings

581.1General Description

This work includes furnishing and installing pot bearings (fixed and expansion types). Use the quality, type, and size designated in this specification, on the plans, or ordered by the Engineer. 581.1.01 Definitions General Provisions 101 through 150. 581.1.02 Related References

ASTM A 709 Grade 36 (ASTM A 709M Grade 250) A 709 Grade 50 (A 709M Grade 345) AASHTO LRFD Bridge Design Specifications AASHTO LRFD Bridge Construction Specifications 581.1.03 Submittals Provide the following reports to the Project Engineer and the Office of Materials and Testing: • Certified test reports • Materials certificates • Certificate of Compliance to conform with the requirements in this Specification • Shop drawings • Certification 932 932 932 932 932 932

Submit to the Engineer shop drawings and calculations for pot bearings for review and approval. Submission should be made electronically in a portable document format (pdf) and include an index. Format all drawings to fit 11 in. x 17 in. (279 mm x 432 mm) paper. Present calculations to fit 8.5 in. x 11 in. (216 mm x 297 mm) paper. The submission shall be prepared and stamped by the Design Engineer who shall be registered as a Professional Engineer in the State of Georgia. Include the following on the drawings: • Bearing plan and elevation • Complete details and sections that show the materials incorporated into the bearing • ASTM or other material designations • Vertical and horizontal load capacity • Rotation and translation capacity • Compression stress on sliding surfaces and elastomeric surfaces at maximum and minimum design loads • Complete design calculations • Complete erection and installation procedure

Have the pot bearing manufacturer furnish the following to the Project Engineer and the Office of Materials and Testing: • Certified test reports • Material certificates • Certificate of compliance to conform with these Specifications for each bearing furnished

581.2Materials

Ensure that materials meet the requirements of the following Specifications: Material Section Expanded Mortar 506 Painting 535 Structural Steel 851 Anchor Bolts, Nuts, and Washers 852.2.02 Elastomeric Bearing Pads 885 Bearing Plates with PTFE Surfaces 887

Use the stainless-steel sliding surfaces indicated below: • Stainless Clad Steel Plate: Minimum eight percent stainless steel conforming to the requirements of ASTM A 264 (both Shear Strength and Bond Strength tests in 8.13 and 8.14 of ASTM A 264 are required). Use stainless steel cladding that meets Type 304. Use backing steel (base metal) that meets ASTM Designation A 709 Grade 50W (A 709M, Grade 345 W). • Stainless Steel Plate Welded to A Steel Backup Plate: Use at least 16 gage (1.6 mm) thickness of the stainless steel plate that meets ASTM 240 Type 304. Use steel backing plate that meets ASTM Designation A 709 Grade 50W (A 709M Grade 345W) unless otherwise indicated on the Plans. Use qualified welders to weld the stainless-steel plate to the steel backing. Furnish welding procedures and welder qualification documents to the Department for review and approval prior to fabrication. Weld entirely around the perimeter of the stainless-steel plate. 933 933 933 933 933 933

• Solid Stainless-Steel Plate: Mill-finish the stainless-steel sliding surfaces to a maximum surface roughness of 20 micro-inches (0.50µm), RMS, according to the requirements of ANSI Standard B 46.1. Remove and replace, at no additional cost to the Department, bearing plates whose stainless-steel sliding surfaces have been scratched or damaged.

Use structural steel for the masonry plates and the components of the bearings that meet the requirements of these ASTM Specifications: • ASTM A 709, Grade 36 (ASTM A 709M, Grade 250) • A 709, Grade 50 (A 709M, Grade 345) Machine the base pot from a solid steel plate.

Use anchor bolts, including nuts and washers, that meet the requirements of Subsection 852.2.02.

Ensure that the elastomeric material used as the confined medium within the pot is 100 percent virgin chloroprene (“Neoprene”) that meets the requirements of Section 885. Ensure that the elastomer is a minimum Grade 2 and has a durometer hardness of 50 ± 5. Ensure that the sealing rings for containing the elastomer in the pot bearings are as specified by the pot bearing manufacturer, and meet the following requirements: • Made of brass or stainless steel • Withstands and transmits all imposed loading • Allows free movement of the piston • Contains the elastomer within the pot under the maximum static and dynamic loading • Prevents contamination of the elastomer with foreign matter

Set anchor bolts in preformed or drilled holes using expanded mortar that meets the requirements of Section 506.

Paint exposed steel of each bearing assembly other than stainless steel according to System VI of Section 535. Take care to keep Polytetrafluroethylene (PTFE) or sliding surfaces free of paint.

Design, fabricate, and erect pot bearings according to these Specifications and the applicable requirements of the following Standard Codes and Specifications. • Section 501, including supplements • AASHTO LRFD Bridge Design Specifications • AASHTO LRFD Bridge Construction Specification Additional design parameters with which the pot bearing manufacturer must comply:

PTFE surface.

1) Stainless steel sliding surface to completely cover PTFE surface in all operating positions of the bearing. 2) Position the stainless-steel sliding surface so that the sliding movement causes the dirt and dust accumulation to fall from the surface of the stainless steel.

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PTFE nor 8 percent of filled PTFE surfaces.

ring to prevent extrusion of the elastomeric material.

Pot bearings with a design similar to that shown on the Plans may be used provided the bearings to be substituted are approved by the State Bridge Engineer and comply with the following:.

used to prevent extrusion of the elastomeric material.

requirements. 581.2.01 Delivery, Storage, and Handling

Have each pot bearing assembled at the plant, marked for identification, and delivered to the construction site as a complete unit. Each bearing shall be marked with permanent match-marks to indicate the normal position of the bearing.

Follow these guidelines to transport, store, and handle pot bearings during construction:

components of the pot bearings. Ensure that the Fabricator also follows the above requirements. During transportation and storage, cover the bearings with moisture-proof and dust-proof covers. 935 935 935 935 935 935

581.3Construction Requirements

581.3.01 Personnel

Have the bearing manufacturer provide a skilled representative who is certified by the manufacturer to be experienced in similar installations. The representative shall: • Give aid and instruction during the pot bearing installation. • Be present during the initial bearing installation. • Be present during welding of the pots to the masonry plates, if not performed in the manufacturer’s shop. • Remain on the job until the bearing installation proceeds without trouble and until the workmen are experienced with the work for each installation as determined by the Engineer. Arrange to have the manufacturer’s skilled representative present whenever requested by the Engineer. 581.3.02 Equipment General Provisions 101 through 150. 581.3.03 Preparation General Provisions 101 through 150. 581.3.04 Fabrication

Ensure that the PTFE, including its connection to its backup material, conforms with the requirements of Section 887, except as modified in this Specification. Have the PTFE sliding surface bonded under factory-controlled conditions, or mechanically connect it to a rigid backup material that can resist bending stresses of the sliding surfaces. As an alternate, PTFE material of twice the thickness specified above may be recessed for half its thickness in the backup material. Ensure that it is at least 1/8 in (3 mm) thick.

If welding procedures established and approved by the Engineer restrict the temperature of the bond area to no greater than 300 °F (150 °C), welding to steel plates with a bonded PTFE surface is permitted. Use temperature-indicating wax pencils or other suitable means to determine the temperature.

plane surface.

the approved adhesive system manufacturer’s written instructions.

factory treated by the sodium napthalene or sodium ammonia process.

PTFE surfaces.

upon which the bearings will be installed.

construction site as a complete unit. Ensure that the bearings have permanent match-marks to indicate the normal position of the bearing. 936936936936936936

581.3.05 Construction

Place bearings at their proper locations before erecting the superstructure supported by the bearings.

Install pier tops horizontal at the correct elevation with a plus or minus tolerance of zero. Do not install the

masonry plates until the Engineer accepts the pier tops.

Cast anchor bolts in the concrete or set them in preformed holes, unless otherwise shown on the Plans. If

setting them in preformed holes, fill the preformed holes in the concrete substructure with expanded mortar.

packed and flush with the top surface of the concrete.

has not been in place at least 7 days.

Set the masonry plates to the proper elevation on the previously finished concrete pads.

• Adjust the expansion bearings from the normal position at 60 °F (15 °C) to allow for the ambient

temperature during erection or casting.

• Adjust the pot bearings to allow them to move when dead loads are applied. Ensure that the

bearing is properly positioned and parallel (free from rotation) after applying the dead load.

• Adjust the bearings horizontally on the masonry plate to properly fit the superstructure members

being erected.

581.3.06 Quality Acceptance

Instruct the manufacturer to furnish facilities to test and inspect the completed bearings in the plant or at an

independent test facility. An approved testing laboratory or the manufacturer supervised by an approved independent

expert shall perform the testing.

Follow these testing guidelines:

• Instruct the manufacturer to allow the Engineer and Inspectors access to the plant and test facilities.

• Furnish certified test reports, materials certificates, and a certificate of compliance to conform with the

requirements in the specifications.

• Perform testing according to Section 887 and this Specification. The Department reserves the right to sample

and test the material and pot bearing assemblies as shown in Section 106.

• Test complete bearing assemblies or a specially manufactured pot bearing prototype that has a capacity of

400 kips (181 000 kg).

Successfully tested full-size bearings that meet the requirements of this subsection and have no damaged

components, finishes, or surfaces may be used in construction. Provide prototype pot bearings, if used, at no

additional expense to the Department.

Specific Items tested are as follows:

Perform tests to determine the static coefficient of friction of the first movement under a load of 3,500 psi (25 MPa)

on a piston area applied continuously for 12 hours before testing. Determine under a load of 2,000 psi (14 MPa) on

a piston area the following: 937937937937937937

unfilled PTFE surfaces.

(0.4 mm per sec). Values shall not exceed 10 percent for filled PTFE surfaces and 6 percent for unfilled

PTFE surfaces.

movements at a speed of less than 1 ft. per min. (5 mm per sec). Values shall not exceed those indicated in

step 2 above. Signs of bond failure or other defects are cause for pot bearing rejection.

Perform, under maximum design loads, proof loading and compression deflection tests on a full-size pot bearing.

Subject an approved sample of filled PTFE or unfilled PTFE to a static pressure of 3,500 psi (25 MPa) for at least

24 hours. Ensure that the PTFE material is bonded or mechanically connected to its backup material in the same

way as the pot bearing.

Apparent cold flow of the PTFE material is cause for pot bearing rejection.

581.3.07 Contractor Warranty and Maintenance

General Provisions 101 through 150.

581.4Measurement

Pot bearing assemblies are measured by Lump Sum for each bridge. Determine the actual quantities required before

submitting the bid.

581.4.01 Limits

General Provisions 101 through 150.

581.5Payment

The work in this Specification will be paid for on a Lump Sum basis.

Payment is full compensation for:

• Furnishing materials and equipment including structural steel components of the bearings, masonry plates,

top plates, sole plates, PTFE, elastomers, anchor bolts, and welding

• Designing the pot bearing

• Performing tests

• Furnishing prototype bearings and test samples

• Performing Work as described and specified in this Specification or the Plans

• Providing incidentals to complete the work

Payment will be made under:

Item No. 581 Pot bearings, bridge No.___ Per lump sum

581.5.01 Adjustments

General Provisions 101 through 150.. 938 938 938 938 938 938