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Structures Session – Part 1 Overview

Structures Session – Part 1 Overview. BD-628 Waterproofing Changes Strike-Off-Letter 431-11-03 Bearing Cleaning, Painting, Lubrication & Resetting. Structures Session – Part 1. Clean, Lube, and Reset of Bronze Bearings. History and Use. Problems with Bronze Plate Bearings.

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Structures Session – Part 1 Overview

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  1. Structures Session – Part 1 Overview • BD-628 Waterproofing Changes • Strike-Off-Letter 431-11-03 • Bearing Cleaning, Painting, Lubrication & Resetting

  2. Structures Session – Part 1 Clean, Lube, and Reset of Bronze Bearings

  3. History and Use

  4. Problems with Bronze Plate Bearings • Accumulation of dirt, debris, moisture, and salts cause corrosion. • Excess corrosion can “lock up” the bearings, reduce bearing area, and/or cause misalignment. • Excess stress, vibration, creep, and ultimately failure can occur.

  5. Typical Problems (continued)

  6. Two Recent Projects: 79 A54: (General picture of bridge) 50 A20: (General picture of bridge)

  7. SR 50 A20, (SR50 over Chartiers Creek) • All bearings were over extended. • Masonry plates had good bearing on concrete, so it was decided that moving sole plates would be easier. • Had to be wary of 12” gas main and bearing eccentricity.

  8. SR 50 0ver Chartiers Creek

  9. SR 50 A20 Repair Procedure • Jack beams, air arc sole plate welds and remove sole plate and bronze shim. • Blast and prime steel. Power tool clean and lubricate bronze. • Align sole plates to allow for design expansion/contraction while staying below max. allowable eccentricity. • Test fit for full contact with all components, and re-weld sole plates.

  10. SR 50 A20 Repair Procedure

  11. SR 50 A20 Repair Procedure

  12. SR 50 A20 Repair Procedure

  13. SR 50 A20 Repair Procedure

  14. SR 50 A20 Repair Procedure

  15. SR 50 A20 Repair Procedure

  16. SR 50 A20 Repair Procedure

  17. SR 50 A20 Repair Procedure Before After

  18. SR 79 A54, (79 SB over SR 51) • Assumed construction errors left most bearings requiring shims – some as high as 1.5” • Some bearings frozen, some misaligned • Over extended on one abutment, under extended on the other.

  19. SR 79 A54

  20. SR 79 A54 Repair Procedure • Jack beams, cut nuts, slot masonry plate to allow for movement. • Power tool clean all components (bronze, steel) • Lube bronze, and prime and lube steel. • Align masonry plates to centerline of bearing and shim to achieve proper alignment with bronze/sole plate. • Test fit for full contact, pour epoxy below masonry plate, allow to cure and de-jack.

  21. SR 79 A54 Repair Procedure

  22. SR 79 A54 Repair Procedure

  23. SR 79 A54 Repair Procedure

  24. SR 79 A54 Repair Procedure

  25. SR 79 A54 Repair Procedure Before After

  26. Modern Use and Testing

  27. Lessons Learned • Measure girder location before starting work. • Check for full bearing before finalizing anything. • Seal weld in addition to transverse welds to keep water out. • Make sure sole plates are oriented properly! • Get Designer/Structure Control Involved!

  28. QUESTIONS? Steve Sneddon Construction Project Manager 412-292-9379 ssneddon@pa.gov

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