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Precast Bent System for Bridges in Seismic Regions

Precast Bent System for Bridges in Seismic Regions. Marc Eberhard, John Stanton Olafur Haraldsson , Todd Janes , Hung Viet Tran University of Washington. NEES & PEER Annual Meeting San Francisco, 8 -9 October 2010. Acknowledgments. WSDOT TRANSNOW Valle Foundation

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Precast Bent System for Bridges in Seismic Regions

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  1. Precast Bent System for Bridges in Seismic Regions Marc Eberhard, John Stanton OlafurHaraldsson, Todd Janes, Hung Viet Tran University of Washington NEES & PEER Annual Meeting San Francisco, 8 -9 October 2010

  2. Acknowledgments WSDOT TRANSNOW Valle Foundation FHWA, Highways for Life Program PEER

  3. Background • Accelerate on-site bridgeconstruction. • Use precast concrete components. • Connection details: • seismic-resistant • construct

  4. Construction Procedure 1) Excavate footing.

  5. Construction Procedure 2) Position and brace precast column.

  6. Construction Procedure 3) Place footing reinforcement and cast.

  7. Construction Procedure • Set cap-beam, grout bars into ducts.

  8. Construction Procedure 5) Place girders, diaphragms and deck.

  9. Connections CIP RC (ref) Precast RC Precast Prestressed Cap-Beam to Column Column to Spread Footing Column to Drilled Shaft

  10. Column-to-Cap-BeamConnection

  11. Cap Beam Connection:Many small bars and ducts Courtesy: BERGER/ABAM Engineers Tight tolerances.

  12. Precast column Precast cap beam 6 # 18 rebar 8.5” corrugated steel ducts High strength grout Cap-Beam Connection:Large bars

  13. Cap-Beam Connection: Conclusions • Failure occurs in the column. • Large-bar precast connection behaves the same as a cast-in-place connection.

  14. Column-to-FootingConnection

  15. Footing Connection: Construction Headed bars

  16. Footing Connection: Headed Bars Strut and Tie Model.

  17. Footing Connection Hooked bars facing out (Conventional cip) Load transfer is tangential to hook. Ineffective!

  18. Footing Connection: Construction

  19. Spread Footing Connection Vertical (gravity) load. Lateral (seismic) load.

  20. Spread Footing Connection:Test After seismic testing. Foundation undamaged.

  21. Spread Footing Connection – Gravity Load Test Column crushed at: 3.5 * (1.25DL + 1.75LL). No damage to footing. No sign of punching failure.

  22. Spread Footing Connection Constructability: • Column has no projecting bars. • No “form-savers”. • Easy to fabricate and transport.

  23. Spread Footing Connection Structural Performance: • Terminators provide better anchorage than hooked bars facing outwards. • Failure in column. Footing undamaged in lateral load and vertical load tests. • Seismic performance as good as, or better than, conventional c.i.p. construction.

  24. Implementation • Bid Opening: • October 14th

  25. Pre-Tensioned System

  26. Pre-Tensioned System PC cap-beam Sleeved strand Bonded rebar Cracking plane Bonded strand c.i.p. footing

  27. Pre-Tensioned System • Pre-tensioning solves corrosion problems perceived to exist in post-tensioning. • Pre-tension in a plant. • Good QC. • Special equipment and extra site time for post-tensioning are not needed. • Can add rebars for energy dissipation.

  28. Thank You

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