La Industria de Madera y la infraestructura publica en USA

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La Industria de Madera y la infraestructura publica en USA

  1. 1. Dr. J. Daniel Dolan, P.E. Professor and Director of Codes and Standards La industria de madera y la infraestructura pública en USA Department of Civil and Environmental Engineering Washington State University P.O. Box 642910 Pullman, Washington 99164-2910 Tel: +1-509-335-7849 Fax: +1-509-335-7632 Email: jddolan@wsu.edu
  2. 2. Timber Bridges have Historically Been Very Important to the Transportation System <ul><li>Initially timber was used because it was available and the Europeans were familiar with the material </li></ul><ul><li>Bridges were covered to protect the wood from the weather </li></ul>
  3. 3. Timber Bridges have Historically Been Very Important to the Transportation System <ul><li>Walls of cover are trusses and span determined the depth of the wall </li></ul><ul><li>Location where bridge rested on foundations had sacrificial members that were replaced as required. </li></ul>
  4. 4. Timber Bridges have Historically Been Very Important to the Transportation System <ul><li>Bridges were used for both truck and automobiles as well as pedestrian </li></ul><ul><li>Most bridges used sawn lumber but many used round timber for all but the wearing surface </li></ul>
  5. 5. Wood in Modern Transportation Structures <ul><li>In the early 1980s the US Congress passed the Timber Bridge Initiative as part of the US Department of Agriculture Forest Service budget </li></ul><ul><li>This law funded at least one modern timber bridge in each state of the US </li></ul>
  6. 6. Environmental Concerns for Preservative Treatments <ul><li>The initiative required that studies be conducted on the environmental impact preservative treatments had on the aquatic life in the streams. </li></ul>
  7. 7. Environmental Concerns for Preservative Treatments <ul><li>Three preservatives are used for timber bridges: </li></ul><ul><ul><li>Creosote </li></ul></ul><ul><ul><li>Pentachlorophenol </li></ul></ul><ul><ul><li>Chromated Copper Arsenate </li></ul></ul>
  8. 8. Environmental Concerns for Preservative Treatments <ul><li>10-15 streams under timber bridges were sampled </li></ul><ul><li>A range of water speeds from rapids to ponds were sampled </li></ul>
  9. 9. Environmental Concerns for Preservative Treatments <ul><li>Findings </li></ul><ul><ul><li>If empty cell technologies were used, there was no measurable differences in the population levels of pollutant-sensitive invertebrate communities </li></ul></ul>
  10. 10. Environmental Concerns for Preservative Treatments <ul><li>Water Chemistry had no measurable differences between the up-stream control samples and the samples taken 100 m down-stream </li></ul>
  11. 11. Timber Use In Guards <ul><li>All bridges require guardrails </li></ul>
  12. 12. Timber Use In Guards <ul><li>All bridges require guardrails </li></ul><ul><li>Some are intended for vehicles only </li></ul>
  13. 13. Timber Use In Guards <ul><li>All bridges require guardrails </li></ul><ul><li>Some are intended for vehicles only </li></ul><ul><li>Some are intended for both vehicles and predestrians </li></ul>
  14. 14. Timber Use In Guards <ul><li>There are different levels of requirements depending on the traffic levels for the highway </li></ul>15 deg 25 deg 20 deg 80 km/h 100 km/h 100 km/h 4 (8,000 kg) (2,000 kg) (820 kg) Van Truck Pickup Truck Small Car Single-Unit     Impact Conditions NCHRP 350 Test level (5) 15 deg 20 deg 20 deg 80.5 km/h 96.6 km/h 96.6 km/h 2 20 deg 20 deg   72.4 km/h 80.5 km/h 1 (8,165 kg) (2,449 kg) (816 kg) Single-Unit Truck Pickup Truck Small Car Medium     Impact Conditions AASHTO Perfomance Level (4)
  15. 15. Timber Use In Guards <ul><li>There are different levels of requirements depending on the traffic levels for the highway </li></ul><ul><li>Wood blocks are extensively used between the rail posts and the rails to increase energy absorption </li></ul>
  16. 16. Timber Use In Guards <ul><li>There are different levels of requirements depending on the traffic levels for the highway </li></ul><ul><li>Wood blocks are extensively used between the rail posts and the rails to increase energy absorption </li></ul>
  17. 17. Timber Retaining Walls <ul><li>Timber has long been used for structural retaining walls </li></ul>
  18. 18. Timber Retaining Walls <ul><li>Timber has long been used for structural retaining walls </li></ul><ul><li>Typically, either Creosote of CCA is used as a preservative </li></ul>
  19. 19. Timber Retaining Walls <ul><li>Shorter walls use timber piles for structural support and timber planks for wall </li></ul><ul><li>Others use beam and tie system </li></ul><ul><li>Important to allow drainage of water to lower loads and provide longevity (30-40 yrs) </li></ul>
  20. 20. Timber Retaining Walls
  21. 21. Timber Retaining Walls
  22. 22. Timber Retaining Walls <ul><li>Some retaining walls can become quite high </li></ul><ul><li>Need to deal with active pressures in soft soils </li></ul>
  23. 23. Current Trends <ul><li>Timber bridges are typically constructed with glued-laminated beams and decks </li></ul><ul><li>Reasons include: </li></ul><ul><ul><li>Cost of labor </li></ul></ul><ul><ul><li>Interaction with asphalt </li></ul></ul><ul><ul><li>maintenance </li></ul></ul>
  24. 24. Current Trends <ul><li>Pennsylvania Study: </li></ul><ul><ul><li>Lower cost </li></ul></ul><ul><ul><li>Aesthetics </li></ul></ul><ul><ul><li>Local Labor Force </li></ul></ul><ul><ul><li>Longer Expected Life Span </li></ul></ul><ul><ul><li>Ease of Construction </li></ul></ul>
  25. 25. Future Directions <ul><li>Timber bridges will be used in secondary highway applications </li></ul><ul><li>Timber bridges will have moderate spans unless used for special applications </li></ul>
  26. 26. Future Directions <ul><li>As “Green” building initiatives continue to grow in popularity, timber will become more competitive </li></ul><ul><li>Control of water is essential to longevity of timber in transportation applications </li></ul>
  27. 27. Muchas Gracias ! ¿Las Preguntas?

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