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Field Testing and Evaluation of a Demonstration Timber Bridge

Field Testing and Evaluation of a Demonstration Timber Bridge. Iowa State University. Travis K. Hosteng, P.E. 2010 ASCE Structures Congress Session: New Perspectives on Timber Bridges May 13, 2010. Overview. Field Testing Project Lab Project Demonstration Bridge Observations/Future Work.

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Field Testing and Evaluation of a Demonstration Timber Bridge

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  1. Field Testing and Evaluation of a Demonstration Timber Bridge Iowa State University Travis K. Hosteng, P.E. 2010 ASCE Structures Congress Session: New Perspectives on Timber Bridges May 13, 2010

  2. Overview • Field Testing Project • Lab Project • Demonstration Bridge • Observations/Future Work

  3. Introduction/Background • 2003 BEC Project • 8 glued-laminated timber girder bridges w/ asphalt wearing surfaces • ~$250,000 project • OR, AL, NY, WI • Significant asphalt deterioration • Results • Differential Panel Deflections • Deck Panel Condition

  4. Field Tests • Field tested 12 timber bridges with asphalt wearing surfaces Elmhurst Moisture Meter w/ 2” pin

  5. Field Tests Cont. • Rolling Static Tests: BDI Strain; Deflections

  6. Typical Wearing Surface Performance • Full-width transverse cracks located at each deck panel interface

  7. Constructed 07/04; Photo taken 08/04 Typical Wearing Surface Performance

  8. Field Test Observations • Diff. Panel Defl. – Cupped Panels

  9. Results – Global Defl. WS Rating* Experimental n: L/n • Lost Creek = 2032 9 • Camp Creek = 1380 7 • Badger Creek = 1150 9 • Russellville = 750 5 • Chambers Co. = 675 6 • Wittson = 600 5 • Butler Co. = 560 2 • Erfurth = 520 4 *Rating Scale: 1-severe; 5-moderate; 9-minor AASHTO=L/500; AASHTO LRFD=L/425; Timber Design Manual=L/360

  10. Results Cont. – Diff. Panel Defl. WS Rating* • Camp Creek = N/A 7 • Lost Creek = N/A 9 • Badger Creek = 0.022 9 • Chambers Co. = 0.027 6 • Russellville = 0.034 5 • Wittson = 0.054 5 • Erfurth = 0.127 4 • Butler Co. = 0.176 2 Experimental (in.): Limit <0.1 in. *Rating Scale: 1-severe; 5-moderate; 9-minor

  11. Field Test Observations • Bridges with higher n-values generally performed better • The condition of the deck panels was a significant factor affecting wearing surface deterioration • Research methods to reduce and remediate diff. panel defl. on both new and existing bridges • Further research into the design of asphalt mixes for wearing surfaces on timber bridges

  12. Introduction/Background Cont. • 2005 BEC Project • Constructed full-scale timber bridge • ~$150,000 project • ISU Structures Laboratory • Single span, 16ft wide • Reduce Differential Panel Deflections • Deck Modification Alternatives • Test Alternative in the field

  13. Laboratory Bridge • 31-ft single span • Four Girders • 16-ft wide • 4’ x 5 1/8” Deck Panels

  14. Deck Panel Joint Alternatives Plywood Steel Plate Steel Plate w/ Bolts FRP Dowels Mastic Tape

  15. Test Results 0.10 in. Limit Suggested by Timber Manual

  16. Lab Bridge Results • Alternatives Reduced Diff/Defl. • Important Alt. Qualities • Effectiveness • Cost • Constructability! • Top Three: Dowels, Steel Plate, Plywood • Selected Alternative: Plywood

  17. Demonstration Timber Bridge Project

  18. Objective • Design Full-scale Glued-laminated Timber Bridge • Utilize Selected Alternative • Document: • Design • Construction • Serviceability Performance • Live Load Performance • Final report

  19. Demonstration Bridge Design

  20. Plywood Layout

  21. Demonstration Bridge Design Span 1 Span 2

  22. Demonstration Bridge Construction

  23. Demonstration Bridge Construction

  24. Demonstration Bridge Construction

  25. Demonstration Bridge Construction

  26. Demo Bridge – Inspection Resutls • Span w/o Plywood • Span w/ Plywood

  27. Demo Bridge – Test Results

  28. Test Results Cont.- Differential Deflections • Span w/o Plywood • Span w/o Plywood

  29. Demo Bridge – Conclusions/Recommendations • Plywood • reduces differential panel deflections • easy install • Alters asphalt cracking pattern • Future investigations: • Plywood pattern • Tongue/Groove plywood • Asphalt Mix Design

  30. Thank You!

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