P E R Bridge Component Characterization - PEERpeer.berkeley.edu/events/annual_meeting/2001annualmtg/... · E R Bridge Component Characterization ... Ł Monolithic reinforced concrete

2001 PEER Annual Meeting

PPEEEERR

Bridge ComponentCharacterization

Stephen MahinByron and Elvira Nishkian Professor of Structural Engineering

University of California at Berkeley


Key Elements

� Approach slab

� Abutments

� Foundations

� Movement Joints

� Columns/Piers

� Superstructure

� Nonstructural Features


PEER Bridge Program

Focus on:

� Monolithic reinforcedconcrete bridgeconstruction

� New rather than olderconstruction detailing

� Representative of:� Viaducts

� Overcrossings

� Major interchanges


Bridge Research Program

Seismic Hazard

� Intensity Measures

Demand Model

� Damage Measures

Capacity Model

� Performance Measures

Decision Model

� Decision Measures



Seismic Hazard


Demand Model

� Damage Measures

Capacity Model


Decision Model


Improved soil-pile-interactionmodels

Improved models for RCcolumns and connections

Testing of columns andconnections to improveunderstanding of behavior andvalidation of numerical models

Database development onperformance measures given ademand



Seismic Hazard


Demand Model

� Damage Measures

Capacity Model


Decision Model


Assess IM-DM pairing and sensitivity

Sensitivity of response to groundmotion characteristics

Sensitivity of response to analysisprocedures

Define Damage Measures for variouselements and systems

Assess Uncertainty in Predicting

Performance Measures



Seismic Hazard


Demand Model

� Damage Measures

Capacity Model


Decision Model


OverallAssessment ofPerformanceEvaluationProcess�.


Seismic Demands

Effect of long duration groundmotions (PI: Eberhard)

Large magnitude events (M=8 & 9)� Near and distant sites

� Stiff and soft soil conditions

Simple bridge idealization� Well and poorly confined columns

� Analytical models calibrated toexisting data and new test results

Sensitivity of various damageintensity parameters to groundmotion and structural characteristics

� Assess design recommendations

Effect of near-fault pulsemotions (PI: Mahin)

Near-fault motions� Effect of ground motion directivity

� 1,2 and 3 components of excitation

Simple bridge idealizations� Ductile columns with circular and

interlocking spiral confinement

� Calibrated to shaking table tests

Analysis procedures (elastic responsespectrum and time history analysis vs.various nonlinear techniques)

� Assess design recommendations


Seismic Demands

Probabilistic Seismic Demand Analysis (PI: Stojadinovic)

Focuses on assessing statistical relation between Damage Measuresand Intensity Measures

� Idealized three dimensional models ofbridges with various geometries

� Damage Measures (peak local curvature,peak and residual displacement, etc.)

� Intensity Measures (Spectral displacement at various periods, etc.)� Assess sensitivity of performance to ground motion characteristics

(magnitude, distance de-aggregatization)� Assess Damage Measure-Intensity Measure pairing for different bridge

configurations and characteristics


Spirally Reinforced Column Tests

Test Matrix� Loading history

� Traditional cyclic� Pulse initiated cyclic� Variable axial load� Shaking table testing

� Loading rates:Fast and quasi-static

� Aspect ratios: Moderate and low

� Cross-sectionCircular and interlocking spirals


Effect of Axial Load Variation

Baseline Column

� Circular, spirallyreinforced crosssection

� -1/4 scale (16-in. dia.)

� Aspect ratio of 6

� 1% longitudinal steel

� 0.07f�cAg

PI: Xiao

� Axial Load� Constant (0, 0.3f�cAg)

� Proportional to lateral loading

� Two cases of nonsyncronizedaxial loading (vertical ororthogonal effects)

� Monotonic or cycliclateral loading

� Has effect on hystereticbehavior, p.h. length, andfailure mode


Rate of Loading Effects

� Baseline column used

� Dynamic analyses conducted toassess local strain rates for avariety of near-fault records

� Ideal loading history established

� A small, but measurable rateeffect was identified

� Plastic hinge length smaller thanfor cyclic loading, resulting ininitial underestimate of flexuralcapacity -25

-20

-15

-10

-5

0

5

10

15

20

25

-6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6

Displacement (inches)

VP1: Dynamic

VP2: Static

Moment-CurvaturePrediction

-6

-4

-2

0

2

4

6

0 20 40 60 80

Time, (s)

Dis

pla

cem

ent,

(in

)

PIs: Ashford and Filiatrault


Effect of Loading History

� Baseline column cross-section used

� Aspect ratios selectedproduce columns with little,limited or high ductility

� Traditional cyclic loadinghistories compared to onesinitiated by pulses

� Strong analytical component

Characterize sensitivity of response of spirally reinforcedconcrete columns having different aspect ratios to loading history(PI: Pardoen)

0.0 1.0 2.0 3.0 4.0 5.0 6.0Displacement (inches)

0.0

5.0

10.0

15.0

20.0

Load

(ki

ps)

0 1 2 3 4 5 6 7 8

Drift (Displacement/height * 100%)

0

10

20

30

40

50

60

70

80

90

100

Load

(kN

)

UCI-6UCI-1UCI-2Moment-curvature ModelCalibrated FE ModelUCSD-1 PulseUCSD-1 CyclicUCSD-2 PulseUCSD-2 CyclicUCSD-3 PulseUCSD-3 Cyclic


Shaking Table Tests

Unidirectional

Bidirectional

Earthquake 1 Olive View

(Northridge, 1994)

Specimen A1

Specimen A2

Earthquake 2 Llolleo (Chile,

1986)

Specimen B1

Specimen B2

Objectives:� Data to validate analytical models� Compare performance for near-fault

and long-duration excitations� Assess effects of multiple

components of ground motion� Assess cumulative damage models

PI: Mahin


Column Performance

After Design Level Event (R=4) After First Maximum Level Event (µ=6)


Condition at end of tests

Fractured Spiral Fractured Bar

Buckled Bars

After sixth repetition ofMaximum Run - Olive View


Peak Displacement Response

Maximum Bottom and Top Disp. in Long and Lat directions, Test A2

0.00

1.00

2.00

3.00

4.00

5.00

6.00

7.00

8.00

9.00

10.00

A2-Run1Yield

A2-Run2Design 1

A2-Run3Max 1

A2-Run4Design 2

A2-Run5Max 2

A2-Run6Max 3

A2-Run7Design 3

A2-Run8Max 4

A2-Run9Max 5

A2-Run10Max6

Dis

pla

cem

ent

[in

]

Long. Column Disp Lat. Column Disp Long. Peak Ground Disp Lat. Peak Ground Disp

First BarBuckling

Bar Fracture

Bi-directional input has limited effect and in the cases considered extends life of column


Long Duration Excitations

1985 Llolleo, Chile Record


Correlation With AnalysisDisplacement for test A2-Run2 in the Longitudinal direction

-4

-3

-2

-1

0

1

2

3

4

5

6

0 2 4 6 8 10 12 14 16 18 20

Time

Test-LongFedeas-Long

Test Data

Fedeas Fiber element

Run A2 - Run 2Olive View Record at Design LevelFiber Model


Interlocking Spiral Columns

� Column widely used wheredifferent strengths or stiffnessesare required along eachdirection

� Relatively little researchThree specimens � 1/6 scale� 1% Long. steel� 1989 Los Gatos Record

�Strong axis only�Bi-directional

� Tabas Record�Bidirectional


Interlocking Spiral Columns


Bi-directional Response

-8 -6 -4 -2 0 2-8

-7

-6

-5

-4

-3

-2

-1

0

1

2

0 5 10 15 20 25 30-6

-5

-4

-3

-2

-1

0

1

2Analytical Experimental

Analysis

Test

Time, secD

ispl

acem

ent,

in.

Dis

plac

emen

t, in

.

Displacement, in.


Connection behavior

� Assess effect of rate ofloading on current andpre-1971 column tobent cap connectiondesign details

� Four 1/2 scale models

� Cyclic and pulse-initiated cyclic loadhistories considered

PIs: Ashford and Filiatrault

Pre-1971 Detail

Current Detail


Connection Behavior

Test 4 - Dynamic Pre-71 Design

-60

-40

-20

0

20

40

60

80

100

-5 -4 -3 -2 -1 0 1 2 3 4 5

Displacem ent ( inches)

Fo

rce

(kip

s)

SM3 Test (Pre -71 de sign)

-200

-150

-100

-50

0

50

100

150

200

-8 -6 -4 -2 0 2 4 6 8 10

Displacem ent (inches)

Fo

rce

(kip

s)

Non-Pulse Test Cure nt Design

-100

-80

-60

-40

-20

0

20

40

60

80

100

-8 -6 -4 -2 0 2 4 6 8

Displacem ent (inches)

Fo

rce

(k

ips

)

Test 3 - Dynamic Current Design

-100

-80

-60

-40

-20

0

20

40

60

80

100

-8 -6 -4 -2 0 2 4 6 8

Displacement (inches)

Pre-1971 Detail Current Connection Detail

Static Cyclic

Dynamic PulseDynamic Pulse

Static Cyclic


PEER Bridge Performance Database

http://www.structures.ucsd.edu/PEER/peer.html

Quantitative Definitions ofPerformance LevelsProvided


Performance Parameter Prediction

� Database of 400+ column testscompiled (circular & rectangular)

� http://ce.washington.edu/~peera1

� Analysis models for variousperformance parametersestablished and evaluated usingsynthesized data

Uncertainties in Structural Performance ParameterEstimates (PI: Eberhard)Assesses predictions of key performance (spalling, bar buckling)and modeling (strength, stiffness) parameters given demandestimates

0

0.01

0.02

0.03

0.04

0.05

0.06

0 0.5 1 1.5 2

Transverse Reinforcement Ratio (%)

Cal

cula

ted

Co

mp

ress

ive

Str

ain

Onset of Spalling

Onset of Bar Buckling


Pulling it all together

� Test bed structures withreal world complexity

� Seismic Hazardassessment

� Study of DamageMeasures based onsimplifying analyticalassumptions

� Selection of PerformanceMeasures

� Assessment of Capacity

� Evaluation of probability ofachieving performance for agiven hazard

� Integrate information/resultsdeveloped by others

� Assess/improve methods

� Identify needed research

Fragility Assessment of Bridge Systems (PI: Seible,Elgamal, Conte)


Future

� Pull information together andevaluate

� Assess and improvenumerical models

� Theoretical issues related toelement and system capacitydefinitions

� System level tests

� Modeling and assessmenttools for: abutments,foundations, etc.

� Information on DecisionVariables (direct and indirectcosts, interruption of service)

� Assess performanceobjectives inview of results

� Work withtransportationsystem group

Documents

P E R Bridge Component Characterization - PEERpeer.berkeley.edu/events/annual_meeting/2001annualmtg/... · E R Bridge Component Characterization ... Ł Monolithic reinforced concrete