ROCKFALL! Glenwood Canyon, CO

							Fabrication and Placement of
Drilled Shaft Reinforcing Cages
AASHTO Subcommittee on Construction
      Virginia Beach, Virginia
          August 2, 2011
            Barry D. Siel, P.E.
       Senior Geotechnical Engineer
                FHWA-RC
Attributes of Rebar
Cages to Assure Good
Constructability
Longitudinal Reinforcing
Selecting Bar Sizes: A Practical
Compromise

• Make Bars as Large As Possible for Better Flow
     Paths for Concrete (Constructability)
• Make Bars as Small As Possible to Minimize
     Crack Size (Durability)
• Splices
    Use Only Lap or Mechanical Splices
    Locate Splices As Deep As Possible
Splice 50 ft Below
Top of Shaft
Transverse Reinforcing
Transverse Reinforcing
Cage Design for Constructability


•   Clear Spacing Between All Bars  5 D of Largest
    Coarse Aggregate or 5 inches, (whichever is
    larger) to Allow Placement of Concrete
       Bundle Bars if Necessary
•   Tie Transverse Steel Every Lap
Concentric Rebar Cages
External Centralizer
External Centralizer
External Centralizer
Concrete Cover and Location Tolerance
Partial-Length
Rebar Cage
Essentials of Cage Design for
Constructability

 •   No Out-Hooks if Casing Method is Possible
 •   Make Cages Full Depth if Casing Method is
       Possible
 •   Do Not Allow Welding Unless Weldable Steel is
        Specified
Support Cage Above Bottom
Internal Bracing
Internal Bracing
Cage with Internal Bracing
Lifting Cages
Lifting Cages
Lifting Cages
Lifting Cages
Lifting Cages
Lifting Cages
Practical Tips on Storing and Handling
Rebar Cages
     • Storage
          Keep it clean
     • Cage Pick Up:
         No permanent distortion
         Use of temporary stiffeners
     • Use of Centralizers: External & Internal
     • NDT Access Tubes: Straight & Parallel
      QUESTIONS?
AASHTO Subcommittee on Construction
      Virginia Beach, Virginia
          August 2, 2011

            Barry D. Siel, P.E.
       Senior Geotechnical Engineer
                FHWA-RC