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FHWA High Performance Concrete Research Program Dr. Benjamin Graybeal, P.E. Lou Triandafilou, P.E. Turner-Fairbank Highway Research Center Federal Highway Administration. FHWA HPC Program. Section 5202(b)(3)(B) of SAFETEA-LU RT&E on HPC bridges Fiscal 2006 through 2009

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fhwa high performance concrete research program dr benjamin graybeal p e lou triandafilou p e

FHWAHigh Performance Concrete Research ProgramDr. Benjamin Graybeal, P.E.Lou Triandafilou, P.E.

Turner-Fairbank Highway Research Center

Federal Highway Administration

fhwa hpc program
FHWA HPC Program
  • Section 5202(b)(3)(B) of SAFETEA-LU
    • RT&E on HPC bridges
    • Fiscal 2006 through 2009
    • ≈ $2.9M per year after adjustments, etc.
      • R&D at TFHRC
      • D&D at Headquarters
      • TT through Resource Center
fhwa hpc research program
FHWA HPC Research Program
  • FHWA “Bridge of the Future” initiative
    • 100-year service live w/ little or no maintenance
    • Significantly reduced construction time
    • Easily widened or adapted to new demands
    • Significantly reduced life-cycle cost
    • Significantly improved resistance to typical and extreme natural and man-made hazards
    • Integrated substructure and superstructure design and construction
    • Elimination of vertical and lateral clearance problems
fhwa hpc research program4
FHWA HPC Research Program
  • Program developed by FHWA in consultation with stakeholders and industry
  • Primary topics to be addressed
    • Lightweight Structural Concrete
    • Shear of Non-Prestressed Elements
    • HPC Deck Behavior (Cracking, Durability, etc.)
    • NDE Methods for Void Detection in PT Ducts
lightweight structural concrete
Lightweight Structural Concrete
  • AASHTO LRFD allows lightweight
    • Includes arbitrary definitions
    • Based on dated research from a limited compressive strength range
lightweight structural concrete6
Lightweight Structural Concrete
  • NCHRP 18-15
    • Parallel effort ongoing with proposals due today
    • Effort focused on equilibrium densities less than 125 pcf
    • RFP focused on material characterization with limited structural testing for verification of behaviors
lightweight structural concrete7
Lightweight Structural Concrete
  • Research Objective
    • Address perceived shortcomings in LRFD with regard to equilibrium densities less than 140 pcf
      • Are across-the-board resistance factor modifications correct?
      • Are predictor equations acceptably accurate?
      • What about equilibrium densities between ‘normal weight’ and ‘sand lightweight’?
lightweight structural concrete8
Lightweight Structural Concrete
  • Focal Areas
    • Structural behavior research focusing on higher strength girders and higher durability decks
    • Material characterization research focusing on strength, serviceability, stability, and production issues
lightweight structural concrete9
Lightweight Structural Concrete
  • First Steps
    • Synthesis of existing research results and the state-of-the-practice regarding the use of lightweight concrete in highway bridges
      • Currently underway
      • Scheduled for completion in January 2007
lightweight structural concrete10
Lightweight Structural Concrete
  • Phase 1: Material Property Characterization of Structural Lightweight Concrete
    • Literature Search
    • Identification of Mix Designs
      • Range of equilibrium densities
      • Range of lightweight coarse aggregates
      • Mixes representative of normal/intended use
      • At least 3 mixes for superstructures
      • At least 3 mixes for decks
lightweight structural concrete11
Lightweight Structural Concrete
  • Phase 1: Material Property Characterization of Structural Lightweight Concrete (continued)
    • Test Program
      • Strength (Compressive, Tensile, Modulus)
      • Stability (Creep, Shrinkage, CTE)
      • Durability (Freeze-Thaw, Scaling, Chloride Pen)
    • Compile Results
      • Develop predictor equations
      • Prepare final report
lightweight structural concrete12
Lightweight Structural Concrete
  • Phase 2: Behavior of Structural Lightweight Concrete Bridge Components
    • Literature Search
    • Identification of Mix Designs
      • Use mix designs from Phase 1
lightweight structural concrete13
Lightweight Structural Concrete
  • Phase 2: Behavior of Structural Lightweight Concrete Bridge Components (continued)
    • Test Program
      • Shear capacity in superstructure members
      • Transfer and development length of strands
      • Development length of rebar
      • Prestress losses
      • Confinement requirements for anchorage regions
      • Punching shear capacity
lightweight structural concrete14
Lightweight Structural Concrete
  • Phase 2: Behavior of Structural Lightweight Concrete Bridge Components (continued)
    • Test Program (continued)
      • Testing completed on full-scale components
    • Compile Results
      • Develop predictor equations for relevant behaviors
      • Prepare final report
shear capacity of non prestressed high strength concrete members
Shear Capacity of Non-Prestressed High-Strength Concrete Members
  • AASHTO LRFD Shear Provisions
    • High-strength concrete use restricted to situations where physical tests have demonstrated applicability of relationships
    • NCHRP 12-56 focused heavily on prestressed girders
    • Other members composed of HSC have not been thoroughly addressed
shear capacity of non prestressed high strength concrete members16
Shear Capacity of Non-Prestressed High-Strength Concrete Members
  • Research Objective
    • Extend applicability of shear provisions for normal weight concrete to 18 ksi compressive strength without any restriction on structural applications
shear capacity of non prestressed high strength concrete members17
Shear Capacity of Non-Prestressed High-Strength Concrete Members
  • Research Plan
    • Perform literature search for relevant prior work
    • Develop practical HPC mix designs with the desired properties
    • Perform full-scale component tests to determine the relevant behaviors
    • Report results
hpc deck behavior
HPC Deck Behavior
  • HPC Deck Issues
    • HPC deck cracking is an ongoing concern
    • Early age and longer term behaviors
    • HPC may exacerbate issues due to potential higher strengths & stiffnesses
    • Mix designs, construction practices, lack of oversight, etc. may all be underlying causes
hpc deck behavior19
HPC Deck Behavior
  • Research Objective
    • Identify the primary root causes of underperformance of HPC bridge decks
    • Develop and/or verify remedies

National focus … range of issues and solutions

hpc deck behavior20
HPC Deck Behavior
  • Research Plan
    • Compile experiences and best practices from around the U.S.
    • Establish, verify, develop, and/or compile:
      • good mix designs
      • effective construction practices (e.g., curing duration and equipment, limiting weather factors)
    • Perform full-scale laboratory testing as necessary
    • Report findings and disseminate results
nde methods for detecting voids in post tensioning ducts
NDE Methods for Detecting Voids in Post-Tensioning Ducts
  • Strand Deterioration Resulting from Voids
    • Detailing and construction practices can lead to voids in tendon ducts
    • Voids already exist due to past practices
    • Future voids are likely even with better detailing and better construction practices
    • Locating voids can allow for remediation prior to strand deterioration
nde methods for detecting voids in post tensioning ducts22
NDE Methods for Detecting Voids in Post-Tensioning Ducts
  • Research Plan
    • Synthesize existing practice and recent research regarding void and deteriorated strand detection
    • Compile a state-of-the-research report
    • Develop experimental research plan based on synthesis results and availability of funds