Presentation on theme: "Precast Bent System for Bridges in Seismic Regions Marc Eberhard, John Stanton Olafur Haraldsson, Todd Janes, Hung Viet Tran University of Washington NEES."— Presentation transcript:
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 WSDOTTRANSNOW Valle Foundation FHWA, Highways for Life Program PEER
2) Position and brace precast column. Construction Procedure
3) Place footing reinforcement and cast. Construction Procedure
4)Set cap-beam, grout bars into ducts. Construction Procedure
5) Place girders, diaphragms and deck. Construction Procedure
PrecastPrestressedCIP RC (ref) PrecastRCCap-Beam to Column Column to Spread Footing Spread Footing Column to Drilled Shaft Drilled ShaftConnections
Cap Beam Connection: Many small bars and ducts Courtesy: BERGER/ABAM Engineers Tight tolerances.
Precast column Precast cap beam 6 # 18 rebar 8.5 corrugated steel ducts High strength grout Cap-Beam Connection: Large bars
Cap-Beam Connection: Conclusions Failure occurs in the column. Failure occurs in the column. Large-bar precast connection behaves the same as a cast-in-place connection. Large-bar precast connection behaves the same as a cast-in-place connection.
Footing Connection: Construction Headed bars
Headed Bars Footing Connection: Headed Bars Strut and Tie Model.
Footing Connection Hooked bars facing out (Conventional cip) Load transfer is tangential to hook. Ineffective!
Spread Footing Connection: Test After seismic testing. Foundation undamaged.
Spread Footing Connection – Gravity Load Test Column crushed at: 3.5 * (1.25DL LL). No damage to footing. No sign of punching failure.
Spread Footing Connection Constructability: -Column has no projecting bars. -No form-savers. -Easy to fabricate and transport.
Spread Footing Connection Structural Performance: Terminators provide better anchorage than hooked bars facing outwards.Terminators provide better anchorage than hooked bars facing outwards. Failure in column. Footing undamaged in lateral load and vertical load tests.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.Seismic performance as good as, or better than, conventional c.i.p. construction.
Implementation Bid Opening: October 14 th October 14 th
Pre-Tensioned System 1.Pre-tensioning solves corrosion problems perceived to exist in post-tensioning. 2.Pre-tension in a plant. Good QC.Good QC. Special equipment and extra site time for post-tensioning are not needed.Special equipment and extra site time for post-tensioning are not needed. Can add rebars for energy dissipation.Can add rebars for energy dissipation.