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?