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LRFD Metal Loss and Service-Life Strength Reduction Factors for Metal-Reinforced Systems (2011) / Chapter Skim
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Appendix A - Details of Metal Loss Models
Pages 51-55

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From page 51...
... Therefore, the AASHTO metal loss model is used in this study to compute nominal sacrificial steel requirements that serve as a basis for calibration of resistance factors for LRFD. This appendix will describe earlier metal loss models and corresponding data sources leading to the development and adoption of the AASHTO model.
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From page 52...
... also includes a factor of 2 to consider the maximum metal loss. Although corrosion rates for both galvanized steel and carbon steel clearly vary exponentially with respect to time, simple models involving linear extrapolation have been proposed and are considered valid (Elias, 1990)
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From page 53...
... The outstanding limitations of each data source involve a lack of data to document the corrosion/metal loss of the base steel subsequent to depletion of zinc from the surface. Thus, similar to the Stuttgart model, the AASHTO model considers steel consumption to begin after the zinc layer is consumed, but at a rate observed from samples of plain steel appropriate to the age of the reinforcements.
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From page 54...
... , and the two models render nearly the same metal loss when t = 64 years. Apparently, using a higher corrosion rate for zinc of 4 μm/year renders metal loss consistent with the Darbin model, which directly considers applying a factor of 2 to consider maximum metal loss.
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From page 55...
... <6. Caltrans reduces the steel corrosion rate to 13 μm/yr for backfill meeting additional requirements for select granular fill.
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Key Terms

  • plain steel
  • loss models
  • corrosion rates
  • steel requirements
  • loss model

  • corrosion rate
  • service life
  • galvanized steel
  • base steel
  • aashto metal

  • maximum metal
  • design life
  • steel subsequent
  • fill characteristics
  • aashto model

  • mse reinforcements
  • fill materials
  • steel reinforcements
  • steel appropriate
  • considers applying

  • interim model
  • aashto requirements
  • zinc consumption
  • earlier metal
  • original equation

  • loss measurements
  • typical mse
  • rate obtained
  • nential equation
  • renders metal


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