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Durability Assessment of Structures: Best Practices for Longevity and Performance

This presentation by Dr. Paul J. Tikalsky from The Pennsylvania State University outlines a comprehensive approach to durability-based design in structures, focusing on environmental exposure and desired service life. It covers essential steps including defining performance metrics, modeling performance versus exposure, and specifying materials and methods. Key aspects such as inspection, life-cycle design, and consensus research directions for durability effects are emphasized. This session was part of Euro-SiBRAM 2002, highlighting the importance of robust, sustainable design practices in construction.

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Durability Assessment of Structures: Best Practices for Longevity and Performance

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  1. Session 6 (B)Durability Assessment of Structures Dr. Paul J. Tikalsky, P.E., FACIThe Pennsylvania State University USA

  2. Durability Based Design • 6 steps • Defining environmental exposure • Defining the desired life • Defining required performance • Modeling performance vs. exposure vs. life • Specifying materials and methods • Inspection of construction Euro-SiBRAM’2002 Prague, June 24 to 26, 2002, Czech Republic

  3. Environmental Exposure • Chemical Exposure • Sulfate concentration • Cation (Ca, Mg, Na) • Chloride concentration • Carbon dioxide or monoxide concentration • Acid concentration and type • Other chemical concentrations Euro-SiBRAM’2002 Prague, June 24 to 26, 2002, Czech Republic

  4. Defining the Service Life Euro-SiBRAM’2002 Prague, June 24 to 26, 2002, Czech Republic

  5. Performance Characteristics Standard Test Method HPC performance grade 1 2 3 CP Chloride penetration, Coulombs AASHTO T 277 4000X>2500 2500X>1500 1500>X CS Compressive Strength, MPa AASHTO T 22 24X<32 32X<55 55X<82 SD Strength ratio 28 day fc 7 day fc AASHTO T 22 1.15 1.33 1.45 SU Sulfate resistance (expansion) ASTM C 1012 X<0.10% At 6 months X<0.10% At 12 months X<0.10% At 18 months Defining Performance Euro-SiBRAM’2002 Prague, June 24 to 26, 2002, Czech Republic

  6. Performance, Exposure & Life Based on 75 year life expectancy Euro-SiBRAM’2002 Prague, June 24 to 26, 2002, Czech Republic

  7. Specifying Materials & Methods • Very difficult to use pure performance based specifications • Prescription of best practices are necessary • Prequalification of materials • Prequalification of Contractor • QC/QA Plan and implementation • Training and certification of workforce Euro-SiBRAM’2002 Prague, June 24 to 26, 2002, Czech Republic

  8. Inspection • Assessment based design must be verified by inspection • Inspection is essential to improve the models from laboratory to field performance. Euro-SiBRAM’2002 Prague, June 24 to 26, 2002, Czech Republic

  9. Life Cycle Design • How can designers choose a terminal time, Tt, considering….. • real estate developers are designing for both obsolescence • The infrastructure environment (bridges, government building, utilities) are designing for extended life • Everyone is designing for sustainability Euro-SiBRAM’2002 Prague, June 24 to 26, 2002, Czech Republic

  10. Consensus Research Direction • How should interactions between different durability effects be addressed? • What type of data is needed to develop reasonable models? Euro-SiBRAM’2002 Prague, June 24 to 26, 2002, Czech Republic

  11. Models and Design Decisions • Do sufficient time-dependent models exist? Which one’s should be used? • Are variations in the variables sufficiently known to use simulation based design programs? • What training needs to be conducted to assist designers in making life-cycle design decisions? Euro-SiBRAM’2002 Prague, June 24 to 26, 2002, Czech Republic

  12. 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

  13. Chloride Penetration Model • C (x,t) = chloride concentration at depth x after time t • Co = equilibrium chloride concentration at the surface of the concrete • erf = the error function, a standard mathematical function • Dc = chloride diffusion constant. Euro-SiBRAM’2002 Prague, June 24 to 26, 2002, Czech Republic

  14. 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

  15. Subsidence Cracking Model • p = probability of settlement cracking • y = 1.37 - 0.58x1 - 0.56x2 + 0.27x3 [inch] • = 1.37 - 0.023x1 - 0.56x2 + 0.011x3 [mm] • x1 = concrete cover • x2 = concrete cover / bar size • x3 = concrete slump Euro-SiBRAM’2002 Prague, June 24 to 26, 2002, Czech Republic

  16. 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

  17. Chloride Concentration and Diffusion Constant

  18. Chloride Concentration and Cover Depth

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

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