Limit States and Design Parameters for Flexurally Dominated RC Columns
description
Transcript of Limit States and Design Parameters for Flexurally Dominated RC Columns
PPEEEERR
2002 PEER Annual Meeting
Limit States and Design Parameters for Flexurally Dominated RC Columns
Marc O. Eberhard Myles Parrish, Mike Berry University of Washington
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?
• For a specified deformation, what is the likelihood that a flexurally dominant reinforced column will suffer a particular level of damage?
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
Typical Progression of Damage
Onset of Spalling
Onset of Bar Buckling
Loss of Axial Load
DAMAGEMEASURE
SAFETYIMPLICATION
REPAIRMEASURES
LOSS OFFUNCTION
Flexural Cracks
Steel YieldingNone
SignificantResidual Cracks
None
Onset of Spalling
None
Significant Spalling Marginal
EpoxyInjection/Patching
PossibleShort Term
Onset of BarBuckling
Spiral/HoopFracture
Longitudinal BarFracture
Low to High PartialReplacement
ModerateTerm
Loss of Axial Load Critical Fully Replace Long Term
Demand Parameters
Peak Deformation• Drift Ratio• Plastic Rotation• Displacement Ductility• Maximum Compressive Strain• Maximum Tensile Strain
Deformation Controlled
PPEEEERR
2002 PEER Annual Meeting
Database of Test Results
Typical F
Properties Table
Test Results
References
Properties Table
Test Results
References
Properties Table
Test Results
References
Properties Table
Test Results
References
Spiral-Reinforced Columns(149 tests)
Rectangular Columns(204 tests)
Columns with Splices(7 tests)
Retrofitted Columns(11 tests)
PEER Column Performance Databasehttp://ce.washington.edu/~peera1
Strong Floor
Reference Column
Cross-Head
Hammerhead
High-StrengthThreaded Rod
HydraulicActuator
TestColumn
North-SouthStrong Wall
Typical Test Configuration
Typical Force-Displacement History
-3 -2 -1 0 1 2 3-75
-50
-25
0
25
50
75
Nelson and Price, 2000 (P3)Displacement (in.)
Ap
pli
ed F
orce
(k
ips)
-3 -2 -1 0 1 2 3
Displacement (in.)
-75
-50
-25
0
25
50
75
Ap
pli
ed F
orce
(k
ips)
Nelson and Price, 2000 (P3)
SP BB
AX
PPEEEERR
2002 PEER Annual Meeting
Correlate Deformation Measures and Observed Damage:
Onset of Spalling
Drift Ratio at Onset of Spalling
Drift Ratio at Onset of Spalling
Concrete Strain at Onset of Spalling
Concrete Strain at Onset of Spalling
Why So Much Scatter??
• Observer Subjectivity
• Discrete Levels of Imposed Deformation
• Model Inaccuracy– complicated phenomena– effects of cycling – force-deformation response
(P/f'cAg < 0.35)
Kmeas/Kcalc
0.0
0.5
1.0
1.5
2.0
HOGN KP MAND SAAT
0 < L/D < 3
3 < L/D < 8
ME
AN
(P/f'cAg < 0.35)
Kmeas/KcalcC
OV
HOGN KP MAND SAAT
0%
20%
40%
60%
PPEEEERR
2002 PEER Annual Meeting
Correlate Deformation Measures and Observed Damage:
Onset of Bar Buckling
Drift Ratio at Onset Bar Buckling
Rectangular Reinforced
Drift Ratio at Onset Bar Buckling
Rectangular Reinforced
Drift Ratio at Onset Bar Buckling
Rectangular Reinforced
DRbuckle (%)= 2.5 (1-P/Agf’c)(1+8sfy/f’c)
Strain at Onset of Bar Buckling
Strain at Onset of Bar Buckling
buckle = 0.015+0.02sfy/f’c
PPEEEERR
2002 PEER Annual Meeting
Application
Probability of Bar Buckling
Conclusions
• Database provides the information needed to systematically evaluate the accuracy of force-displacement and damage models.
• 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.
• For a given level of deformation, one can estimate the likelihood of reaching a particular level of damage.
PPEEEERR
2002 PEER Annual Meeting
Questions?