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Implementation of FRP Girders in Short Span Bridges: Ponte Dickey Creek

Implementation of FRP Girders in Short Span Bridges: Ponte Dickey Creek. M.D. Hayes 1 , J.J. Lesko 1 C. Waldron 2 , T.C Cousins 2 , Dan Witcher 3 , G. Barefoot 3 , Jose Gomez 4 1 Department of Engineering Science & Mechanics 2 Department of Civil and Environmental Engineering

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Implementation of FRP Girders in Short Span Bridges: Ponte Dickey Creek

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  1. Implementation of FRP Girders in Short Span Bridges: Ponte Dickey Creek M.D. Hayes1, J.J. Lesko1 C. Waldron2, T.C Cousins2, Dan Witcher3, G. Barefoot3, Jose Gomez4 1Department of Engineering Science & Mechanics 2Department of Civil and Environmental Engineering Virginia Tech, Blacksburg, VA 3Strongwell, Corp., Bristol, VA 4VTRC/VDOT, Charlottesville, VA

  2. Where is Virginia Tech? Maryland West Virginia Kentucky Ponte Dickey Creek Strongwell, Corp. Tennessee North Carolina

  3. Rt. 601 Bridge over Dickey CreekMarion, VA 35’

  4. Extren™ 36” Double Web Beam (DWB) Characteristics • Pultrusion • Both Hybrid, Unbalanced Non-Symmetric Layup • Vinyl Ester Resin • Glass 0°, ±45° & 90° plies • Hybrid: Carbon in top and bottom flanges • Produced as part of the NIST ATP program Dimensions in inches

  5. 36” DWB Performance & the Rt. 601 Bridge • Preliminary design & deflection • Bridge rails and Connections • Proof testing 5x design load • Average properties & performance • Failure test • Post failure bridge performance • Design guidelines

  6. Preliminary Design Assumptions • 38 ft clear span (use 39’ with bearing pads) • Curb-to-curb width = 28 ft • Assume wheel load distribution = s/5 (From Standard Spec for steel girder timber deck, shown to be conservative for the Tom’s Creek Bridge) • Assume dynamic load allowance = 1.3 (From Standard Spec yet potentially not conservative as shown by TCB) • Assume conservative FRP beam properties: • E = 6.0 Msi, I = 15291 in4, kGA = 20 Msi-in2 • Shear deformation accounts for ~12% of total deflection

  7. Deflection Criteria: Targeting L/800 L/800 requires 3.1 ft spacing But, 3.5 ft chosen

  8. a 6’ 2’ 14’ a 38’ span 38’ span b 6’ 2’ 28’ width 28’ width Loading Arrangements HS20-44 Loading HS20-AML Loading rear axle middle axle front axle

  9. LDF Approach* Finite Difference Model HS20-AML HS20-44 HS20-44 HS20-44 FRP girder spacing: 42” uniform 42” uniform Variable: 36”, 52” Max moment (ft-kips): 191 197 224 200 Max shear (kips): 10.9 18.3 N/A N/A Max deflection: L/760 L/710 L/600 L/660 HS20-44 standard loading controls design Resultant Moments, Deflections • For s = 3.5 ft, s/5 = 0.7 and # girders = 8 • Assuming equal spacing, resulting loads: * Calculations verified by Appendix A in the AASHTO Bridge Specifications: 432.1 x 3.5 / (2 x 5) x 1.3 = 197 ft-kips

  10. 8-Girder Designs

  11. Diaphragm Detail

  12. Deck to Girder Connection

  13. Connection Testing Connection produces less than 5% composite action and therefore is not considered in the design of the bridge

  14. Bridge Rails

  15. Crash Tested Rail Design Crash tested at Univ. of Nebraska on a 5 1/8” deep transverse glue laminated deck to TL-4

  16. Girder Testing

  17. Girder Test Set-Up

  18. 16'-6" 6'-0" 12'-0" 19'-6" 39'-0" Stiffness & Failure Test:Set-Up and Gage Plan D B D A (bottom of top flange) Shr1-9 A 3" Spc. A (top of bottom flange) B Wire Pot Wire Pots 1-center, 2-3' either side of flange D = Delamination Bridge (1 gage top and bottom of flange) B = Bending Bridge (3 gages across flange) A = Axial Gage Shr = Shear Bridge (9 sets placed around load point)

  19. Moment - Deflection to Failure Mfail/M5x = 1.7 Mfail/Mservice = 7.2 AASHTO Service Moment

  20. Top Flange Damage Failure under loading point

  21. Top Flange Damage Failure along carbon/glass interface

  22. Moment-Deflection(Post Failure) 450 36” hybrid DWB retains 70% of its stiffness after failure 400 350 300 250 Run 1 Moment (kip-ft) AASHTO Service Moment Run 2 200 Run 3 150 100 50 0 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 Midspan Deflection (in.)

  23. Girder Verification & Performance Summary

  24. Summary of 36” DWB Properties Weibull Mean:6.21±0.27 26.7±3.5 5.37±0.19 • Conservative properties assumed in design E = 6 Msi & kGA = 20 Msi•in2 • This is not a statistical mean or allowable. • Ultimate strain = 3170 me (top flange) • Max moment = 1415 kip-ft comes from 1 test on beam #13.

  25. Predicted Load Distribution • s/5 assumed in bridge design & analysis • Analytical model run to assess LDF, e.g. HS20 loading: S/4.2

  26. Load Distribution (Half Bridge Width)

  27. Design guidelines

  28. 36”DWB Design guide under development Modified LRFD Approach • 8” Deep DWB Design Guide • Deflection (A&B Allowables) • Strength (A&B Allowables) • Stability • Bearing • Connections • Fatigue & Long Term Reliability based approach to assessing A & B basis Allowables, as described through Weibull Statistics

  29. Resistance, R B-Basis A-Basis Level of Risk 36” & 8” DWB Design Guide Approach User supplies loads and level of acceptable risk based on change in Resistance Cumulative Probability

  30. Summary • Rt. 601 designed for AASHTO HS20-44 loading with DLA (L/650 predicted) • Worst case LDF s/4.2 • Girder to timber deck connections provide no composite action • Crash tested bridge rail for transverse glue laminated deck • Exceeds a factor of safety of 7 (RC structures F.S.2) • Ponte Dickey Creek installed by VDOT • Design guide under development

  31. Acknowledgements • VDOT/VTRC - Dr. Jose Gomez, Julius Volgyi, Malcom Kerley • VDOT Bristol District - Chris Blevis, Gary Lovins • FHWA, John Hooks & http://ibrc.fhwa.dot.gov

  32. Questions?

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