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Session 4 Reference Values for Durability Design

Session 4 Reference Values for Durability Design. Dr. Paul J. Tikalsky, P.E., FACI The Pennsylvania State University USA. Defining Durability. Detailed Knowledge Structural Requirements Environment Material Science Deterioration Mechanisms. Structural Requirements.

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Session 4 Reference Values for Durability Design

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  1. Session 4 Reference Values for Durability Design Dr. Paul J. Tikalsky, P.E., FACIThe Pennsylvania State University USA

  2. Defining Durability • Detailed Knowledge • Structural Requirements • Environment • Material Science • Deterioration Mechanisms Euro-SiBRAM’2002 Prague, June 24 to 26, 2002, Czech Republic

  3. Structural Requirements • Define the precise design function • Compression, Tension, Shear, Combined? • Stiffness? Brace? Load Sharing? • Define the structural design RV • Define the long term and short term behavioral requirements of the structure • Define the desired design life Euro-SiBRAM’2002 Prague, June 24 to 26, 2002, Czech Republic

  4. Define the Environment • Concentrations of chemical and gases • Wet/Dry cycles • Freeze/Thaw cycles • Physical loadings • Abrasion • Fluid contact and velocity • Vibrations/Repeated cycles Euro-SiBRAM’2002 Prague, June 24 to 26, 2002, Czech Republic

  5. Level of Chemical Exposure • Chemical Exposure • Sulfate concentration (0-5% SO4-2) • Chloride concentration (0-3 kg/m3) • Carbon dioxide or monoxide concentration • Acid concentration and type • Other chemical concentrations Euro-SiBRAM’2002 Prague, June 24 to 26, 2002, Czech Republic

  6. Creating Reference Values • Reference Values for Durability depend on multiple variables • Desired years of service • Acceptability or Consequences of deterioration (nuclear power plant or retail space) • Compounding exposure conditions • Time of testing or evaluation Euro-SiBRAM’2002 Prague, June 24 to 26, 2002, Czech Republic

  7. Material Science Models • Appropriate models must exist for the prediction of deterioration • Time based models that progress with predictably changing exposure conditions Euro-SiBRAM’2002 Prague, June 24 to 26, 2002, Czech Republic

  8. Chloride Diffusion Model C(x,t) = chloride concentration t = time x = depth Co = surface chloride concentration Dc = chloride diffusion constant erf = Error Function Euro-SiBRAM’2002 Prague, June 24 to 26, 2002, Czech Republic

  9. Chloride Concentration and Diffusion Constant

  10. Chloride Concentration vs Time Euro-SiBRAM’2002 Prague, June 24 to 26, 2002, Czech Republic

  11. Subsidence Cracking Model • p = probability of settlement cracking • y = 1.37 - 0.023x1 - 0.56x2 + 0.011x3 • x1 = concrete cover, mm • x2 = concrete cover / bar size • x3 = concrete slump, mm Euro-SiBRAM’2002 Prague, June 24 to 26, 2002, Czech Republic

  12. Permeability • K C= permeability coefficient • Q = rate of flow • H/L = ratio of head of fluid to percolation length • A = cross section area under pressure Euro-SiBRAM’2002 Prague, June 24 to 26, 2002, Czech Republic

  13. Chloride Penetration • Test Method: AASHTO T277 (Coulombs passed in 6 hours) Euro-SiBRAM’2002 Prague, June 24 to 26, 2002, Czech Republic

  14. Euro-SiBRAM’2002 Prague, June 24 to 26, 2002, Czech Republic

  15. Ex: Defining Permeability Performance Euro-SiBRAM’2002 Prague, June 24 to 26, 2002, Czech Republic

  16. Ex: Defining Shrinkage Performance Euro-SiBRAM’2002 Prague, June 24 to 26, 2002, Czech Republic

  17. Ex: Defining ASR Performance Euro-SiBRAM’2002 Prague, June 24 to 26, 2002, Czech Republic

  18. Ex: Defining Sulfate Performance Euro-SiBRAM’2002 Prague, June 24 to 26, 2002, Czech Republic

  19. Models and Design Decisions • Do models exist to predict durability based performance? • Are the models based on materials science? • How can tests at the time of construction be verified by field performance? Euro-SiBRAM’2002 Prague, June 24 to 26, 2002, Czech Republic

  20. Combined Effects • Many durability problems are a result of multiple distress mechanisms. • How can a more holistic model be developed and implemented? (e.g. “Life 365”) Euro-SiBRAM’2002 Prague, June 24 to 26, 2002, Czech Republic

  21. Prof. Paul J. Tikalsky, P.E., FACIPenn State University Transportation Infrastructure Lab. 3127 Research DriveState College, PA 16801 USATikalsky@psu.edu Euro-SiBRAM’2002 Prague, June 24 to 26, 2002, Czech Republic

  22. Chloride Concentration and Cover Depth

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