Dacio Marin III, P.E. Bridge Division Texas DOT

1. Accelerated Bridge Construction Recent TxDOT ABC Projects Iowa DOT ABC Workshop August 2008 Dacio Marin III, P.E. Bridge Division Texas DOT

2. Overview • ABC on Off-system bridges • ABC on On-system bridges • What’s next?

3. Our Bridges … • 50,000 bridges in the state of Texas • 8% of the total number of bridges in the nation, and • About total number of bridges of the four states that border Texas • TxDOT builds 600~800 bridges each year • 250 bridges each year by others

4. ABC on Off-System Bridges

5. Typical Off-System BridgeReplacement Environment • Virtually All Stream Crossings • Short Overall Length with 1 – 3 Short Spans • 40 to 80 ft Each Typically • 24 – 30 ft Roadway Width • ADT Usually Low • Greater Probability of Overtopping • Remote and Difficult Site Access • Usually Involve Road Closure • ROW Limits, Existing Structure Make Phasing and Temp. Detours Difficult

6. Rapid Construction Considerations • Coordinate with local officials • Ensure utilities are clear ahead of letting • Determine working day charges • Consider LDs & road-user costs • Allow adequate time for staging of materials • Traffic, detour route, material delivery

7. Simplified Geometry • Constant or no skew • No horizontal curves • No flares (width transitions) • No superelevation transitions • Complicated geometry can better be handled on the roadway than the bridge

8. Prestressed Box Beams

9. Prestressed Double Tee Beams

10. Prestressed Slab Beams

11. Decked Slab Beams

12. Texas ABC Off-System Bridge

13. Cottonwood Creek BridgeWilliamson County

14. Design Challenges Shallow depth Longer span Long detour route Phased replacement not feasible

15. SiteChallenges • Limited ROW • Retaining wall • Existing utilities

16. Minimum On-Site Construction • Before road closure  • Beam, cap, and abutment fabrication • After road closure  • Retaining wall construction • Demolition of existing structure • Bridge and approach construction

17. New Bridge Construction • Total bridge length 100 ft (50’-50’) • Overall width 42 ft • Decked slab beams, precast abutments & bent caps, flowable backfill, steel H-piles, stone riprap • Contract amount $380,700 (bridge only) • $90.60/SF

19. Steel Anchor Plate and Shear Studs

25. Lateral Connector Details

26. Embedded Weld Plates Every 5 Ft

29. Flowable Backfill • Fluid mixture of sand, fly ash, water • 40% air-entrainment without compaction • Self-leveling

30. Project Completed in 33 Days

31. Construction Highlights • Total 33 days of road closure • 6 days total for bridge construction • Overall cost $90/SF ($43 Superstructure + $47 Substructure)

32. Advantages ofDecked Slab Beam • Field welding vs. transverse post-tensioning • No cast in place concrete slab • Minimum disruption of traffic • Fewer beams and fewer joints • Low depth/span ratio (up to 1/30) • Reduced SF costs with increased usage

33. ABC on On-System Bridges

34. US 290 Ramp E-3 in Austin, TexasPrecast Bent Cap, 1996

35. Reduced ramp closure from several weeks to just 6 hours.

36. Pierce Elevated Faster Rehabilitation: 113 spans in 95 days, vs. 1.5 yrs

37. Sponsored Research:“Development of a Precast Bent Cap System” • Development of Connection Types • Grout Pockets • Grouted Vertical Ducts • Bolted Connections • Testing Program (Behavior and Constructability) • Phase I - Pullout Tests • Phase II - Full-Scale Connection Tests • Phase III - Full-Scale Bent Tests • Implementation • Sample Details • Design Methodology • Construction Issues and Specifications

38. Grout Pockets • Technique • precast voids/pockets in cap to contain column connectors • Advantages • flexibility in size and shape • large construction tolerances • simple grouting operation • Disadvantages • cracking potential at large top surface • congestion of reinforcement • larger volume of grout

39. Grouted Vertical Ducts • Technique • steel corrugated ducts embedded in cap to house column connectors • Advantages • inexpensive stay-in-place ducts • minimal reinforcement congestion • limited exposed top surface • minimal volume of grout • Disadvantages • more difficult grout placement

40. Bolted Connection • Technique • ducts embedded in cap house threaded rods tensioned at the top surface • Advantages • cap setting via leveling plates/nuts • post-tensioning option • resistance to larger moments • Disadvantages • more difficult grouting operations • protecting/recessing top anchorage

42. Results of Connection Tests • Phase I anchorage results validated • excellent anchorage and ductility • small crack widths, even at factored loads • no slip between grout, duct, and concrete • shims did not affect performance • yield within 10% of prediction

43. Lake Ray HubbardPlan View of Project Rockwall Exist Embankment Exist EB Bridge Rowlett

44. Lake Ray HubbardPlan View of Project Rockwall New WB Bridge Rowlett

46. Precast Bent Cap Option BENEFITS: TIME, COST, QUALITY, AND SAFETY • Transport of complete caps versus limited volumes of fresh concrete • Bent cap cure time removed from critical path • Controlled environment of casting yard instead of over lake

47. Final Design • 6 ~ #11 Dowels • 4” Dia. Corrugated Galvanized Steel Ducts • #3 Spiral for Confinement

48. Precasting Caps Placing Dowels Construction Sequence

49. Placing Precast Cap Grouting Connection Construction Sequence

50. Lake Belton Precast Hammer Head Caps Bell County, SH 36 Existing Bridge