Short span prebricated county bridge standards

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Short span prebricated county bridge standards

• Concept Development

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Key Considerations

• Prefabricated system to accelerate construction
• Prestressing only in spans where required
• Preference for only one beam width
• Prefabricated or modular abutments
• Use SL-1 Steel Barrier Rail
• Minimize weight of components (lt45,000 Lbs.)
• Preference to avoid transverse post-tensioning
• 24 30 Road widths Spans from 30 70
• 0, 15, 30 degree skews

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What systems are currently being used?

• Internet search of State DOT Standards
• Input from other regional HDR offices

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What are other viable or new systems?

• Internet Search
• DOT Scanning Tour Results

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Predominant Systems

• Precast/Prestressed Concrete Voided Slabs
• Precast/Prestressed Concrete Box Beams
• Precast/Prestressed Deck Bulb T Beams
• Precast/Prestressed Double T Beams
• Precast/Prestressed Inverted T Beams

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Construction Considerations

• Differential Camber (prestressed members)
• Reflective Cracking
• Code Recommended Transverse Post tensioning
• Topping / Wearing Surface
• Barrier Rail Connection
• Skew Effects
• Accommodation of Roadway Crown
• Parallel Wing Abutments

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Proposed System (Precast Abutments)
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Proposed System (Steel Abutments)
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Lab Testing Phase

• Connection of SL-1 Steel Rail
• Transverse Post-tensioning for crowned roadway
• Additional Analysis
• Parametric Study of conventionally reinforced vs.
  prestressed beam span limits

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Discussion

• Transverse connection
• P/T vs. hand tightened tie rod?
• Level of transverse contact force?
• Keyway configuration?
• Keyway grout or UHPC?
• Topped or untopped? (differential camber)

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Discussion

• Abutment Details
• End diaphragm as backwall?
• Anchorage of boxes to integral abutment?
• 3 vs. 4 bearing pads?
• Accommodation of roadway crown