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Reinforcing Concrete Bridge Decks with PreFabricated FRP Grids

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									Reinforcing Concrete Bridge Decks
 with Prefabricated FRP Grids and
      Stay-in-place Formwork
                     Michael Oliva,
             Lawrence Bank, Jeffrey Russell
           Mack Conachen and F. Greg Ehmke
    Department of Civil and Environmental Engineering
            University of Wisconsin-Madison


                      April 2005
        Presentation Topics

1.   Design Techniques and
     Specifications.

2.   New highway bridge deck
     with FRP stay-in-place (SIP)
     formwork and reinforcing
     (2003).

3.   New highway bridge deck
     with very large prefabricated
     FRP grids (2004).
           Design with FRP:
             Techniques



              ACI 440 (2003):
Guide for the Design and Construction of
 Concrete Reinforced with FRP Bars
        FRP Performance Specifications



      Available WisDOT Special Provisions
IBRC I: Project I.D. 1420-08-74, Bridge B-20-133
Fiber-Reinforced Polymer Deck Form, Stay-In-Place, Item 90002C
Fiber Reinforced Polymer Grid Reinforcement, Item 90002D
Fiber Reinforced Polymer Reinforcing Bar, Item 90007A


IBRC II: Project I.D. 1420-05-71, Bridge B-20-148
Fiber Reinforced Polymer (FRP) Reinforcement Cage, Item 90031G
                                FRP Performance
                                 Specifications

            Table 2. Reporting Requirements for Constituent Materials of FRP Reinforcement
ITEM           TYPE                         MANUFACTURER                    SPECIAL
                                                                            REQUIREMENTS
Fiber          E-glass roving type          E-glass roving manufacturer     NA
               E-glass fabric type(s)       E-glass fabric manufacturer     NA
               E-glass mat type             E-glass mat manufacturer type   NA
Veil           Surface veil type            Surface veil manufacturer       NA
Resin          Vinylester type(s)           Vinylester manufacturer         NA
               Styrene type                 Styrene manufacturer            pph (less than 10 pph resin)
Filler         Filler type                  Filler manufacturer             pph (less than 20 pph resin)
Additives      Shrink additive type         Shrink additive manufacturer    pph (less than 10 pph resin)
Process        Pultrusion die temperature   NA                              NA
               Date of production           NA                              NA
               Lot size                     NA                              NA
              FRP Performance
               Specifications
             Table 1. Limiting Properties for FRP Formwork Panel
            Material Property                         GV2            GV3
Longitudinal Tensile Strength (min)                 552 MPa        414 MPa
Transverse Tensile Strength (min)                   28 MPa         28 MPa
Longitudinal Compressive Strength (min)             552 MPa        414 MPa
Transverse Compressive Strength (min)               69 MPa         69 MPa
Longitudinal Flexural Strength (min)                552 MPa        414 MPa
Long. Short Beam Shear Strength (min)               38 MPa         35 MPa
Longitudinal Tensile Modulus (min)                   31 GPa         28 GPa
Longitudinal Compressive Modulus (min)               28 GPa         21 GPa
In-Plane Shear Stiffness (min)                       3 GPa           2 GPa
Major (longitudinal) Poisson Ratio (min)             0.25           0.25
Fiber Volume Fraction (min)                         45%             45%
Longitudinal Fiber Fraction (min)                   75%             40%
Barcol Hardness (min)                                50              50
Glass Transition Temperature (min)                  95°C            95°C
Water absorption (max)                              1.50%           2.00%
Longitudinal CTE (max) x 10 -6 /°C                   11              11
Transverse CTE (max) x 10 -6 /°C                     54              54
FRP Performance
 Specifications




Performance test for grid
    FRP Performance Specifications

Unique FRP Performance Spec Attributes
• Certified Quality Control testing performed
  by Material Supplier
   – Materials as individual items and as units
   – Constructability testing
• Quality Assurance testing performed by
  UW-Madison
• Sole Supplier and Prequalification
                        Bridge #1
                       IBRC - 2003
• Two 33m spans
• 14 m wide
• 2 lanes of traffic
• 5 prestressed
  concrete girders
• 32° skew
• twin bridges
• 18000 ADT
Bridge cross section
                FRP Reinforcing System




composite stay-in-place deck form panel also acts as
   transverse bottom reinforcing for deck flexure
           FRP Reinforcing System




      FRP prefabricated grid acts as
transverse top reinforcing for deck flexure
           FRP Reinforcing System




   FRP reinforcing bar as needed for:
          T&S crack control,
-M continuity reinforcing over center pier
              FRP Reinforcing System


 FRP grid
 top reinf.

                             FRP rebar
FRP deck
form bottom
reinf.
                            Haunches
                                  Prestressed
Rigid polyurethane foam haunch    Concrete girder




                  Stirrup              Lifting hook
               Placing FRP deck
                     panels
 Ends cut for 32° skew




acts as bottom reinforcing
                             Haunch and grout

Cell ends filled with foam        Overhang
                                  formwork




         Polyurethane
         haunch                Grout- under sip form
                                    FRP rebar
         Epoxy coated rebar
             in parapet




    FRP rebar
-M continuity over    Plastic continuous chair
     mid-pier
                          FRP grid – top reinf.

             Epoxy coated wire     FRP grid T-bar




Mechanical
Splice             FRP 13mm       FRP grid
connector          rebar          cross rod
Concrete pour

   Deck poured in 4 hours
                                    Structural testing
                                 conducted prior to design




             140
             120
             100
Load, kips




             80
             60
             40
                        11'-6" Span, Ult. = 96 kips               9'-10" Span, Ult. = 87 kips
             20
                        8'-0" Span, Ult. = 91 kips                C2 8'-0" Span, Ult. = 130 kips
              0
                   0   0.5              1             1.5             2              2.5           3
                                             Center Deflection, in.
                Quality assurance testing
                conducted after materials
                        delivered
•   FRP Manufacturer Test Reports
•   Longitudinal Tension
•   Longitudinal Short Beam Shear
•   Fiber Volume Fraction
•   Water Absorption
•   Aggregate Distribution
•   Dimensional Tolerance
                             Cost and Labor Data


Cost Comparison                   FRP     Steel   % Difference
                        2
Total Sq. Ft. Cost ($/ft )        70.49   43.64     61.5%
                        2
Deck Sq. Ft. Cost ($/ft )         38.63   13.26     191.4%




Productivity Comparison           FRP     Steel   % Difference
Laborer hours                     310      713      -56.5%
Equipment hours                    35       50      -30.0%
                              Lessons Learned

•FRP reinforcing is a viable option for bridge construction. Bridge
is currently open to traffic.

•FRP bridge had higher installed cost, but required fewer
equipment and labor hours. We anticipate improved long-term
durability.

•The FRP stay-in-place form was the most expensive component
(~65% of all FRP material costs) and was shown to be “over-
designed” during lab testing.
                          Acknowledgements

•   Alfred Benesch Co. – Design Engineer
•   CH2MHill – on-site Resident Engineer
•   Diversified Composites – FRP SIP deck manufacturer
•   FHWA – funding
•   Hughes Brothers, Inc. – FRP rebar manufacturer
•   Lunda Construction – Bridge contractor
•   Strongwell – FRP grid manufacturer
•   University of Wisconsin at Madison – Conducted research
•   Wisconsin Department of Transportation – Owner of bridge
                        Bridge #2
                       IBRC - 2004
• Single 40 m span
• 14 m wide
• 2 lanes of traffic
• 7 prestressed
  bulb-Tee
  concrete girders
• twin bridges
• 18000 ADT
Bridge cross section




         5.6% cross slope
              FRP Reinforcing System


     Entire reinforcing made up of:

double layer 3-D prefabricated FRP grid

 shipped in 44 ft by 8 ft wide panels to
   span full width across bridge deck
                       FRP Reinforcing System
                              Double layer grid
                                fabrication




                               Shear connector

                                           Cross bar
                                                Main bar


Overlap “splice” between
 panels in longitudinal
  direction of bridge
  Prefab FRP Grids
Delivered to Bridge Site
  Haunch
Note: very small formed “span” between
wide flanges
                          Placing FRP grid
                               panels
10 to 12 minutes to set
Each grid panel




Steel rebar deck                   FRP grid deck
            Placing FRP grid
                 panels

All grid panels placed in 1-1/2 days
Before concrete pour
     Placing parapet bars
                               Concrete pour
Very easy to walk and work on top grid!
                    Structural testing
                 conducted prior to design

           220
                    Specimen 8                             Specimen 1: Top Pot.            Specimen 7: Top LVDT
           200
                    *Did not achieve failure.              Specimen 2: Top Pot.            Specimen 8: Top LVDT
           180                                             Specimen 3: Top Pot.

           160
                                                       Specimen 7
           140                                                                               Specimen 1
Load (k)




           120
                                                                                                      Specimen 2
           100
                                                                       Specimen 3
           80

           60

           40

           20                                                                                  16 kip Service Load

            0
             0.00     0.25         0.50         0.75    1.00        1.25   1.50     1.75       2.00      2.25      2.50
                                                           Displacement (in)
           Quality assurance testing
           conducted after materials
                   delivered




Main Bar        Cross Bar       Shear Connector

              Tensile testing
                             Cost and Labor Data


Cost Comparison                    FRP     Steel   % Difference
Total Sq. Ft. Cost ($/ft2)         76.66   57.20     34.0%
Deck Sq. Ft. Cost ($/ft2)          31.33   11.54     171.5%




Productivity Comparison            FRP     Steel   % Difference
Laborer hours                      111      239      -53.6%
Equipment hours                    21.5      32      -32.8%
                                    Load Testing

University of Missouri-Rolla test
                                                Prisms




              Deflection measure with total station
                             Lessons Learned

•FRP bridge had higher installed cost, but required fewer
equipment and labor hours. We anticipate improved long-term
durability.

•IBRC II bridge deck costs were 81% of the IBRC I bridge deck
costs (IBRC I: $38.63/s.f. IBRC II: $31.33/s.f.)

•Shear connectors represented ~30% of FRP reinforcing cost.

•Use alternative method of forming gap between girders to reduce
labor costs further.
                    Acknowledgements

• Alfred Benesch Co. – Design Engineer
• FHWA – funding
• Lunda Construction – Bridge Contractor
• Strongwell – FRP grid manufacturer
• University of Wisconsin at Madison – Conducted
  research
• Wisconsin Department of Transportation – Owner
  of bridge
• University of Missouri-Rolla – Load testing
                        IBRC 3 project
        2005, US I-90/Door Creek, single span, 64.5 ft,
          steel girders, precast full-depth deck panel




½ scale test to prove composite action
    Modified System
Greene County - Missouri
                 Grid system –
                 Upside down


                 1/8” SIP FRP
                 Bottom form
    Modified System
Greene County - Missouri


          Loading 3-D grid and
       bottom sheet form with sand
        to model deflection with
              wet concrete
    New Research - IBRC-4 idea

• Deep arch action with “W” girders:




                    Lateral
                   Constraint
Thank you

								
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