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Limit States and Design Parameters for Flexurally Dominated RC Columns

Investigate likelihood of damage in flexurally dominant RC columns at specified deformations. Research approach involves analyzing key damage levels, deformation parameters, and establishing a comprehensive test results database. Study onset of spalling, bar buckling, and loss of axial load. Correlate damage with various deformation parameters like drift ratio and plastic rotation. Explore typical progression of damage demand parameters. Utilize PEER Column Performance Database for insights. Correlate measured deformations with observed damage for accurate evaluation. Scrutinize effects of cycling, force-deformation responses, and observer subjectivity. Conclude on the importance of the database in model accuracy assessment.

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Limit States and Design Parameters for Flexurally Dominated RC Columns

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  1. Limit States and Design Parameters for Flexurally Dominated RC Columns Marc O. Eberhard Myles Parrish, Mike Berry University of Washington

  2. Objective • P[DM|EDP] • For a specified deformation, what is the likelihood that a flexurally dominant reinforced column will suffer a particular level of damage?

  3. Research Approach • Identify Key Levels of Damage • Consequences • Identify Promising Deformation Parameters • Accuracy, Generality, Reproducibility • Assemble Database of Test Results • Correlate Damage with Deformation Parameters

  4. Onset of Spalling Onset of Bar Buckling Loss of Axial Load Typical Progression of Damage

  5. Demand Parameters Deformation Controlled Peak Deformation • Drift Ratio • Plastic Rotation • Displacement Ductility • Maximum Compressive Strain • Maximum Tensile Strain

  6. Database of Test Results

  7. Typical F Spiral-Reinforced Columns Rectangular Columns (149 tests) (204 tests) Properties Table Properties Table Test Results Test Results References References Columns with Splices RetrofittedColumns (7 tests) (11 tests) Properties Table Properties Table Test Results Test Results References References PEER Column Performance Database http://ce.washington.edu/~peera1

  8. Typical Test Configuration

  9. Typical Force-Displacement History 75 50 25 Applied Force (kips) 0 -25 -50 -75 -3 -2 -1 0 1 2 3 Displacement (in.) Nelson and Price, 2000 (P3)

  10. 75 SP BB 50 AX 25 Applied Force (kips) 0 -25 -50 -75 -3 -2 -1 0 1 2 3 Displacement (in.) Nelson and Price, 2000 (P3)

  11. Correlate Deformation Measures and Observed Damage:Onset of Spalling

  12. Drift Ratio at Onset of Spalling

  13. Drift Ratio at Onset of Spalling

  14. Concrete Strain at Onset of Spalling

  15. Concrete Strain at Onset of Spalling

  16. Why So Much Scatter?? • Observer Subjectivity • Discrete Levels of Imposed Deformation • Model Inaccuracy • complicated phenomena • effects of cycling • force-deformation response

  17. Kmeas/Kcalc 2.0 0 < L/D < 3 3 < L/D < 8 1.5 MEAN 1.0 0.5 0.0 HOGN KP MAND SAAT (P/f'cAg < 0.35)

  18. 60% 40% 20% 0% Kmeas/Kcalc COV HOGN KP MAND SAAT (P/f'cAg < 0.35)

  19. Correlate Deformation Measures and Observed Damage:Onset of Bar Buckling

  20. Drift Ratio at Onset Bar Buckling Rectangular Reinforced

  21. Drift Ratio at Onset Bar Buckling Rectangular Reinforced

  22. Drift Ratio at Onset Bar Buckling DRbuckle (%)= 2.5 (1-P/Agf’c)(1+8sfy/f’c) Rectangular Reinforced

  23. Strain at Onset of Bar Buckling

  24. buckle = 0.015+0.02sfy/f’c Strain at Onset of Bar Buckling

  25. Application

  26. Probability of Bar Buckling

  27. Conclusions • Database provides the information needed to systematically evaluate the accuracy of force-displacement and damage models. • For a given level of deformation, one can estimate the likelihood of reaching a particular level of damage.

  28. Questions?

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