By: Mike Muchard, P.E.

Applied Foundation Testing, Inc.

STATNAMIC Load Testing of High Capacity Marine Foundations

AFT

OutlineOutline

St. George Island Project Description St. George Island Project Description Instrumentation of Cylinder PilesInstrumentation of Cylinder Piles STATNAMIC, Static and Dynamic TestingSTATNAMIC, Static and Dynamic Testing Class A Comparison of Test MethodsClass A Comparison of Test Methods

St. George Island BridgeSt. George Island Bridge

Boh Bros. Construction Boh Bros. Construction Co. Inc,Co. Inc,

Sverdrup Civil, Inc. Sverdrup Civil, Inc. 4.1 Miles4.1 Miles 54” Cylinder Piles54” Cylinder Piles 750 to 900 Ton Factored 750 to 900 Ton Factored

Design Loads.Design Loads. Weathered Limestone Weathered Limestone

Bearing MaterialBearing Material

St. George Island BridgeSt. George Island Bridge Load Test Program Load Test Program

6 Non-Production Test Piles6 Non-Production Test Piles All Test Piles Instrumented All Test Piles Instrumented

with multiple levels of Strain with multiple levels of Strain GagesGages

6 STATNAMIC Tests6 STATNAMIC Tests 4 Static Tests4 Static Tests Dynamic Testing on Test Dynamic Testing on Test

Piles and 50 Production PilesPiles and 50 Production Piles Static and Dynamic Tests Static and Dynamic Tests

Performed by Geo Consultant Performed by Geo Consultant

Pile Instrumentation

Post Tensioning StrainsPost Tensioning StrainsPost Tensioning Strain (All Gages)

-300

-250

-200

-150

-100

-50

0

50

0 200 400 600 800 1000 1200 1400 1600 1800 2000

Time (seconds)

Str

ain

(u

e)

Blue1 ue Blue2 ue Blue3 ue

Green1 ue Green2 ue Red1 ue

Red2 ue Red3 ue Yellow1 ue

Yellow2 ue yellow3 ue

Post Tensioning StressPost Tensioning StressPost Tensioning Stress

-1.100

-1.000

-0.900

-0.800

-0.700

-0.600

-0.500

-0.400

-0.300

-0.200

-0.100

0.000

0 200 400 600 800 1000 1200 1400 1600 1800 2000Time (seconds)

Str

ess

(ksi

)

Blue Green Red Yellow

Post Tension MeasurementsPost Tension Measurements54” Cyclinder Pile54” Cyclinder Pile

EccentricityEccentricity– Non-Uniform Contact Between SegementsNon-Uniform Contact Between Segements– ArchingArching

760 to 1,010 psi Pre-stress760 to 1,010 psi Pre-stress Composite Modulus of Elasticity 5,725 ksiComposite Modulus of Elasticity 5,725 ksi Back Calculated f’c over 10,000 psiBack Calculated f’c over 10,000 psi

Pile Driving and Pile Driving and Dynamic TestingDynamic Testing

(PDA)(PDA)

Soil and Foundation ConditionsSoil and Foundation Conditions

Driving MeasurementsDriving MeasurementsForce vs. Time During Pile Driving

-1000

-800

-600

-400

-200

0

200

400

600

800

1000

1200

1400

1600

0.02 0.03 0.04 0.05 0.06 0.07 0.08 0.09 0.10 0.11 0.12 0.13 0.14 0.15

Time (Seconds)

Fo

rce

(kip

s)

Level 1 Level 2 Level 3 Level 4 PDA Force

Measurements During DrivingMeasurements During Driving

Stresswave Propagation.Stresswave Propagation. Maximum Tension Occurs Near Pile Top.Maximum Tension Occurs Near Pile Top. Toe Remains In Compression.Toe Remains In Compression. Resistance Not Mobilized Simultaneous. Therefore, Resistance Not Mobilized Simultaneous. Therefore,

Modeling Required for Distribution. Modeling Required for Distribution.

1,600 1,600 Ton Static Ton Static

Load Testing Load Testing

2,000 Ton 2,000 Ton STATNAMIC STATNAMIC

DeviceDevice

Statnamic Test Description

Stages of a STATNAMIC TestStages of a STATNAMIC Test

Before Test The Test After Test

Load Produced F = ma

InstrumentationInstrumentation

RAPID LOADING APPARATUS

LOAD CELL

DISPLACEMENTTRANSDUCER

ACCELEROMETER

SIGNAL CONDITIONING

STORAGE ANDDISPLAY

STATIONARY REFERENCE

PILE FOUNDATION

Load Cell Calibrated Load Cell Calibrated Full ScaleFull Scale

Laser Projector &Laser Projector &Capacitive AccelerometersCapacitive Accelerometers

Data AcquisitionData Acquisition

STATNAMIC AnalysisSTATNAMIC Analysis

Load vs. Displacement from STATNAMIC Test - LT-3

-0.75

-0.70

-0.65

-0.60

-0.55

-0.50

-0.45

-0.40

-0.35

-0.30

-0.25

-0.20

-0.15

-0.10

-0.05

0.00

0 250 500 750 1000 1250 1500 1750 2000 2250 2500 2750 3000 3250 3500 3750 4000

Load (kips)

Dis

pla

ce

me

nt

(in

ch

es

)

Statnamic Applied Load Derived Static Load

STATNAMIC Load DistributionSTATNAMIC Load Distribution

Load vs. Time from STATNAMIC Test - LT-3

-4000

-3500

-3000

-2500

-2000

-1500

-1000

-500

0

0.05 0.10 0.15 0.20 0.25 0.30Time (sec)

Lo

ad

(k

ips

)

Load Cell L 1 L 2 L3 L 4 (Bottom)

Force vs. Time During Pile Driving

-1000

-800

-600

-400

-200

0

200

400

600

800

1000

1200

1400

1600

0.02 0.03 0.04 0.05 0.06 0.07 0.08 0.09 0.10 0.11 0.12 0.13 0.14 0.15

Time (Seconds)

Fo

rce

(kip

s)

Level 1 Level 2 Level 3 Level 4 PDA Force

Load vs. Time from STATNAMIC Test - LT-3

-4000

-3500

-3000

-2500

-2000

-1500

-1000

-500

0

0.05 0.10 0.15 0.20 0.25 0.30Time (sec)

Lo

ad

(k

ips

)

Load Cell L 1 L 2 L3 L 4 (Bottom)

Load vs Time from Static Load Test - Test Pile LT-3

-3500

-3000

-2500

-2000

-1500

-1000

-500

0

0 1 2 3 4 5 6Time (hours)

Lo

ad

(k

ips

)

Top L 1 L 2 L 3 L 4 (Bottom)

Three Loading Three Loading

CharacteristicsCharacteristics

STATNAMIC Has Similarities to STATNAMIC Has Similarities to Each Test MethodEach Test Method

Load Duration Precludes StresswavesLoad Duration Precludes Stresswaves Pile displaces as a unit (like a static test)Pile displaces as a unit (like a static test) Much Simpler Analysis Much Simpler Analysis Not an ImpactNot an Impact Rapid Translation, Inertia and Damping must Rapid Translation, Inertia and Damping must

be Subtractedbe Subtracted Rate of Loading Must Also be Considered Rate of Loading Must Also be Considered

Via Rate Factor (Mullins, NCHRP, 2005)Via Rate Factor (Mullins, NCHRP, 2005)

Test Pile 1 - CompositeTest Pile 1 - Composite

Load vs. Displacement from STATNAMIC and STATIC Tests

-3.50

-3.00

-2.50

-2.00

-1.50

-1.00

-0.50

0.00

0 200 400 600 800 1000 1200 1400 1600 1800 2000 2200

Load (kips)

Dis

pla

ce

me

nt

(in

ch

es

)

Static Load Test

Statnamic Load Cycle 1

Statnamic Load Cycle 2

Statnamic Load Cycle 3

Test Pile 1

Test Pile 2 - CompositeTest Pile 2 - Composite

Load vs. Displacement from Statnamic and Static Tests

-0.75

-0.70

-0.65

-0.60

-0.55

-0.50

-0.45

-0.40

-0.35

-0.30

-0.25

-0.20

-0.15

-0.10

-0.05

0.00

0 200 400 600 800 1000 1200 1400 1600 1800 2000 2200 2400 2600 2800 3000 3200 3400

Load (kips)

Dis

pla

ce

me

nt

(in

ch

es

)

Statnamic Load Tests

Static Load Test

Test Pile 2

Test Pile 3 - CompositeTest Pile 3 - Composite

Load vs. Displacement from STATNAMIC and STATIC Tests

-0.75

-0.70

-0.65

-0.60

-0.55

-0.50

-0.45

-0.40

-0.35

-0.30

-0.25

-0.20

-0.15

-0.10

-0.05

0.00

0 200 400 600 800 1000 1200 1400 1600 1800 2000 2200 2400 2600 2800 3000 3200 3400

Load (kips)

Dis

pla

ce

me

nt

(in

ch

es

)

Statnamic Load Test

Static Load Test

Test Pile 3

Test Pile 5 - CompositeTest Pile 5 - Composite

Load vs. Displacement from Statnamic Test and Static Test

-3.00

-2.50

-2.00

-1.50

-1.00

-0.50

0.00

0 200 400 600 800 1000 1200 1400 1600 1800 2000 2200 2400 2600 2800 3000

Load (kips)

Dis

pla

ce

me

nt

(in

ch

es

) Static Load Test

Statnamic Load Test

Test Pile 5

Pile No.

CAPWAPTotal(kips)

StaticTotal(kips)

STATNAMICTotal(kips)

LT-1 1950 2136 2166

LT-2 2016 3109 3052

LT-3 1820 3060 3113

LT-5 2028 2889 2631

CAPWAP – 14 day Re-strikeSTATNAMIC performed 2 days After Static Test LT-5

CAPWAP / StaticCAPWAP / Static

CAPWAP / Static Comparison

0

500

1000

1500

2000

2500

3000

3500

0 500 1000 1500 2000 2500 3000 3500

Static Load (kips)

CA

WA

P (

kip

s)

Under-Prediction

STATNAMIC / StaticSTATNAMIC / Static

STATNAMIC / Static Comparison

0

500

1000

1500

2000

2500

3000

3500

0 500 1000 1500 2000 2500 3000 3500

Static Load (kips)

Sta

tnam

ic L

oa

d (

kip

s)

Friction ComparisonFriction Comparison

Skin Friction Comparison STATNAMIC AND CAPWAP to Static

0

200

400

600

800

1000

1200

1400

1600

1800

2000

0 200 400 600 800 1000 1200 1400 1600 1800 2000

Static Load (kips)

ST

AT

NA

MIC

/ C

AW

AP

(ki

ps)

STATNAMIC

CAPWAP

End Bearing ComparisonEnd Bearing ComparisonEnd Bearing Comparison

STATNAMIC AND CAPWAP to Static

0

500

1000

1500

2000

2500

3000

3500

0 500 1000 1500 2000 2500 3000 3500

Static Load (kips)

ST

AT

NA

MIC

/ C

AW

AP

(ki

ps)

STATNAMIC

CAPWAP

ConclusionsConclusions

Class A Test Method Comparison. Class A Test Method Comparison. Instrumentation Allowed Measurement of Pre-stress, and Instrumentation Allowed Measurement of Pre-stress, and

Load Distribution During Testing.Load Distribution During Testing. Dynamic Testing Under-predicted Capacity 9% to 41%.Dynamic Testing Under-predicted Capacity 9% to 41%. CAPWAP Skin Friction and End Bearing Predictions had CAPWAP Skin Friction and End Bearing Predictions had

Large Disagreement.Large Disagreement. STATNAMIC within 2% of Static Capacity on Three Piles STATNAMIC within 2% of Static Capacity on Three Piles

and 9% Below in the Fourth Pile. and 9% Below in the Fourth Pile.

AFT

Thank YouAny Questions?

Applied Foundation Testing, Inc.