Fabrication and Placement of Drilled Shaft Reinforcing Cages
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
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