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La Industria de Madera y la infraestructura publica en USA
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La Industria de Madera y la infraestructura publica en USA

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La Industria de Madera y la infraestructura publica en USA La Industria de Madera y la infraestructura publica en USA Presentation Transcript

  • 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
  • Timber Bridges have Historically Been Very Important to the Transportation System
    • Initially timber was used because it was available and the Europeans were familiar with the material
    • Bridges were covered to protect the wood from the weather
  • Timber Bridges have Historically Been Very Important to the Transportation System
    • Walls of cover are trusses and span determined the depth of the wall
    • Location where bridge rested on foundations had sacrificial members that were replaced as required.
  • Timber Bridges have Historically Been Very Important to the Transportation System
    • Bridges were used for both truck and automobiles as well as pedestrian
    • Most bridges used sawn lumber but many used round timber for all but the wearing surface
  • Wood in Modern Transportation Structures
    • In the early 1980s the US Congress passed the Timber Bridge Initiative as part of the US Department of Agriculture Forest Service budget
    • This law funded at least one modern timber bridge in each state of the US
  • Environmental Concerns for Preservative Treatments
    • The initiative required that studies be conducted on the environmental impact preservative treatments had on the aquatic life in the streams.
  • Environmental Concerns for Preservative Treatments
    • Three preservatives are used for timber bridges:
      • Creosote
      • Pentachlorophenol
      • Chromated Copper Arsenate
  • Environmental Concerns for Preservative Treatments
    • 10-15 streams under timber bridges were sampled
    • A range of water speeds from rapids to ponds were sampled
  • Environmental Concerns for Preservative Treatments
    • Findings
      • If empty cell technologies were used, there was no measurable differences in the population levels of pollutant-sensitive invertebrate communities
  • Environmental Concerns for Preservative Treatments
    • Water Chemistry had no measurable differences between the up-stream control samples and the samples taken 100 m down-stream
  • Timber Use In Guards
    • All bridges require guardrails
  • Timber Use In Guards
    • All bridges require guardrails
    • Some are intended for vehicles only
  • Timber Use In Guards
    • All bridges require guardrails
    • Some are intended for vehicles only
    • Some are intended for both vehicles and predestrians
  • Timber Use In Guards
    • There are different levels of requirements depending on the traffic levels for the highway
    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)
  • Timber Use In Guards
    • There are different levels of requirements depending on the traffic levels for the highway
    • Wood blocks are extensively used between the rail posts and the rails to increase energy absorption
  • Timber Use In Guards
    • There are different levels of requirements depending on the traffic levels for the highway
    • Wood blocks are extensively used between the rail posts and the rails to increase energy absorption
  • Timber Retaining Walls
    • Timber has long been used for structural retaining walls
  • Timber Retaining Walls
    • Timber has long been used for structural retaining walls
    • Typically, either Creosote of CCA is used as a preservative
  • Timber Retaining Walls
    • Shorter walls use timber piles for structural support and timber planks for wall
    • Others use beam and tie system
    • Important to allow drainage of water to lower loads and provide longevity (30-40 yrs)
  • Timber Retaining Walls
  • Timber Retaining Walls
  • Timber Retaining Walls
    • Some retaining walls can become quite high
    • Need to deal with active pressures in soft soils
  • Current Trends
    • Timber bridges are typically constructed with glued-laminated beams and decks
    • Reasons include:
      • Cost of labor
      • Interaction with asphalt
      • maintenance
  • Current Trends
    • Pennsylvania Study:
      • Lower cost
      • Aesthetics
      • Local Labor Force
      • Longer Expected Life Span
      • Ease of Construction
  • Future Directions
    • Timber bridges will be used in secondary highway applications
    • Timber bridges will have moderate spans unless used for special applications
  • Future Directions
    • As “Green” building initiatives continue to grow in popularity, timber will become more competitive
    • Control of water is essential to longevity of timber in transportation applications
  • Muchas Gracias ! ¿Las Preguntas?