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Soil-Pile Interaction in FB-MultiPier Developed by: Florida Bridge Software Institute Dr. Mike McVay, Dr. Marc Hoit, Dr. Mark Williams Dr. J. Brian Anderson, P.E.

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Page 1: Manual Fbpier

Soil-Pile Interaction in FB-MultiPier

Developed by: Florida Bridge Software Institute

Dr. Mike McVay, Dr. Marc Hoit, Dr. Mark Williams

Dr. J. Brian Anderson, P.E.

Page 2: Manual Fbpier

Session Outline

• Identify and Discuss Soil-Pile Interaction Models– Precast & Cast Insitu Axial T-Z & Q-Z Models– Torsional - Models– Lateral P-Y Models– Nonlinear Pile Structural Models

• FB-MultiPier Input and Output– Example #1 Single Pile

Page 3: Manual Fbpier

Session Outline

• Identify and Discuss Soil-Pile Interaction Models– Precast & Cast Insitu Axial T-Z & Q-Z Models– Torsional - Models– Lateral P-Y Models– Nonlinear Pile Structural Models

• FB-MultiPier Input and Output– Example #1 Single Pile

Page 4: Manual Fbpier

Soil-Structure Interaction

Vertical Nonlinear SpringVertical Nonlinear Spring

Lateral Nonlinear SpringLateral Nonlinear Spring

Torsional Nonlinear Spring

Nonlinear Tip SpringNonlinear Tip Spring

Page 5: Manual Fbpier

Driven Piles - Axial Side Model

z

r

z

r

r + r / r r

z

r

r

+ / r r

r

roo

(Randolph &

Wroth)

Page 6: Manual Fbpier

Driven Piles - Axial Side Model

zZ

r

rd

zd

r

zG

Also:

Substitute: Grd

zd

Rearrange: drG

dz

Previous r

roo

Substitute: drGr

rdz o 0

rm

r0

Also:

2

fi 1

GG

Substitute:

m

0

r

r2

fi

0

1

dr

Gr

rz o

Page 7: Manual Fbpier

Driven Piles - Axial Side Model

f

0 0

0m

0m

0

m

i

00 ,lnz

r

rr

rr

r

r

G

r

T-Z (Along Pile)

0

200

400

600

800

1000

1200

0 0.5 1 1.5

z - Displacement (inches)

Tau

0 (

psf) f = 1000psf

Gi = 3 ksi

Page 8: Manual Fbpier

Driven Piles - Axial Tip Model

2

fi0 P

P1Gr4

-1Pz

Where:

P = Mobilized Base LoadPf = Failure Tip Loadro = effective pile radius = Poisson ratio of SoilGi = Shear Modulus of SoilT-Z (At Tip)

0

50

100

150

200

250

300

0 1 2 3 4 5

z - Displacement (inches)

Tip

Loa

d (k

ips) Pf = 250 kips

Gi = 10 ksi = 0.3r0 = 12 inches

(Kraft, Wroth, etc.)

Page 9: Manual Fbpier

Driven Piles - Axial Properties

• Ultimate Skin Friction (stress), Tauf , along side of pile (input in layers).

• Ultimate Tip Resistance (Force), Pf , at pile tip .

• Compressibility of individual soil layers, I.e. Shear Modulus, Gi , and Poisson’s ratio, .

Page 10: Manual Fbpier

Driven Piles - Axial Properties

• From Insitu Data:– Using SPT “N” Values run SPT97, DRIVEN,

UNIPILE, etc. to Obtain: Tauf , and Pf

– Using Electric Cone Data run PL-AID, LPC, FHWA etc. to Obtain: Tauf , and Pf

– Determine G or E from SPT correlations, i.e. Mayne, O’Neill, etc.

Page 11: Manual Fbpier

Florida: SPT 97 Concrete Piles

Skin Friction, f (TSF)

• Plastic Clay: f= 2N(110-N)/4006

• Sand, Silt Clay Mix: f = 2N(110-N)/4583

• Clean Sand: f = 0.019N

• Soft Limestone f = 0.01N

Ultimate Tip, Pf/Area(tsf)

• Plastic Clay:– q = 0.7 N

• Sand, Silt Clay Mix:– q = 1.6 N

• Clean Sand:– q = 3.2 N

• Soft Limestone– q = 3.6 N

Page 12: Manual Fbpier

Cast Insitu Axial Side and Tip Models

• For soil (sands and clays) – Follow FHWA Drilled Shaft Manual For Sands

and Clays to Obtain Tauf and Pf ( and cu)

– Shape of T-Z cuve is given by FHWA’s Trend Lines.

• User has Option of inputting custom T-z / Q-z curves

Page 13: Manual Fbpier

Cast Insitu - Sand (FHWA):

Qs = D L v’

DL

L/2v’ = L/2

L/2) 0.5 1.2>

Qt = 0.6 NSPT D 2 / 4 NSPT < 75

Page 14: Manual Fbpier

Cast Insitu - Clay (FHWA):

DLQs = 0.55 Cu D (L-5’-D)

Qt = 6 [1+0.2(L/D) ] Cu (D 2 / 4)

Page 15: Manual Fbpier

Cast Insitu trend line for Sand

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

0 2 4 6 8 10

Settlement / Diameter (%)

Mo

bili

zed

Str

ess

/ Ult

imat

e S

tres

s

End Bearing

Side Friction

Page 16: Manual Fbpier

Cast Insitu trend line for Clay

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

0 2 4 6 8 10

Settlement / Diameter (%)

Mo

bili

zed

Str

ess

/ Ult

imat

e S

tres

s

End Bearing

Side Friction

Page 17: Manual Fbpier

Session Outline

• Identify and Discuss Soil-Pile Interaction Models– Precast & Cast Insitu Axial T-Z & Q-Z Models– Torsional - Models– Lateral P-Y Models– Nonlinear Pile Structural Models

• FB-MultiPier Input and Output– Example #1 Single Pile

Page 18: Manual Fbpier

Torsional Model (Pile/Shaft)

• Hyperbolic Model– G and Tauf

• Custom T-

Page 19: Manual Fbpier

Torsional Model (Pile/Shaft)

(rad)

T (F-L)

Tult =1/b

(dT/d(dT/d)=1/a )=1/a G Gii

Tult = = 22 r r22LLultult

T = T = a + b a + b

Tult = f Asurf r

ult = Ultimate Axial Skin Friction (stress)

Page 20: Manual Fbpier

Session Outline

• Identify and Discuss Soil-Pile Interaction Models– Precast & Cast Insitu Axial T-Z & Q-Z Models– Torsional - Models– Lateral P-Y Models– Nonlinear Pile Structural Models

• FB-MultiPier Input and Output– Example #1 Single Pile

Page 21: Manual Fbpier

Lateral Soil-Structure Interaction

Passive State

Active State

Y

Page 22: Manual Fbpier

Near Field: Lateral (Piles/Shafts)

r

y

X

P r dF

Lr

0

2

P r dF

Lr

0

2

r

Y=5”

r

r

Y=0

P = 0 P

Y

Pu

P rStiffClay

Sand &Soft Clay

PPPP

Page 23: Manual Fbpier

P-y Curves - Reese’s Sand

k

m

b/60 3b/80

x = 0

x = x1

x = x2

x = x3

x = x4

u

pk

yk

ym

yupm

pu

m

y

P

ks x

Pu is a function of, , and b

Y is a function of b (pile diameter)

Page 24: Manual Fbpier

0.0

0.5

1.0

PPU

yy50

1.0 8.0

p

p0.5

y

yu 50

1 / 3

Matlock’s Soft Clay

Pu is a function ofCu, , and b

Y is a function of

y50 (50)

Page 25: Manual Fbpier

Reese’s Stiff Clay Below Water

Deflection, y (in.)

Soi

l Res

ista

nce

, p (

lb/in

.)

18Asy506Asy50y50Asy50

Esi = ksx

0.5Pc

0

P Pcy

y0 5

50

0 5. ( ) .

P poffset cy A y

A ys

s 0 055 50

50

1 25. ( ) .

STATIC

Essp

yc 0 0625

50

.

Pc is a function ofC, , ks and b

Y is a function of

y50 (50)

Page 26: Manual Fbpier

O’Neill’s Integrated Clay

0.0

0.5

1.0

RATIO OF DEFLECTION,

RA

TIO

OF

SO

IL R

ESI

STA

NC

E, P

/ P U

201

PP

YYU C

0 5 0 387. ( ) .

Y

YC

P P FOR X XU Cr

PP S S

XXU Cr

F F ( )1

6

Pu is a function ofc, and b

Fs is a function of 100

Yc is a function of b and 50

Page 27: Manual Fbpier

Soil Properties for Standard Curves

• Sand:– Angle of internal friction, – Total unit weight, – Modulus of Subgrade Reaction, k

• Clay or Rock:– Undrained Strength, Cu– Total Unit Weight, – Strain at 50% of Failure Stress, 50

– Optional: k, and 100

Page 28: Manual Fbpier

Soil InformationHelp Menu EPRI (Kulhawy & Mayne)

Page 29: Manual Fbpier

P-y Curves from Insitu Tests

• Cone Pressuremeter

• Marchetti Dilatometer

Page 30: Manual Fbpier

Insitu PMT & DMT Testing

Page 31: Manual Fbpier

Cone Pressuremeter

Page 32: Manual Fbpier

Cone Pressuremeter

(Robertson, Briaud, etc.)

Page 33: Manual Fbpier

Marchetti Dilatometer

Page 34: Manual Fbpier

Pressuremeter P-y Curves Auburn, Alabama

0

200

400

600

800

1000

1200

1400

1600

1800

2000

0 5 10 15 20 25 30 35 40

y (mm)

P (

kN/m

m)

1 m2 m3 m4 m6 m8 m10 m

PMT P-y Curves - Auburn

Page 35: Manual Fbpier

Dilatometer P-y Curves Auburn, Alabama

0

500

1000

1500

2000

2500

0 50 100 150 200 250 300 350

y (mm)

P(k

N/m

)

0.6 m2.1 m3 m4.2 m6.3 m7.2 m

DMT P-y Curves - Auburn

Page 36: Manual Fbpier

Actual and Predicted Lateral Top of Shaft DeflectionsAuburn, Alabama

0

100

200

300

400

500

600

700

800

900

1000

0.0 10.0 20.0 30.0 40.0 50.0 60.0

Lateral Deflection (mm)

La

tera

l L

oad

(kN

)

PMTDMTCPTShaft 1Shaft 2Shaft 3Shaft 6

Auburn Predictions

Page 37: Manual Fbpier

P-y Curves for PMT1Pascagoula, Mississippi

0

1

2

3

4

5

6

0 20 40 60 80 100 120 140 160 180 200

y (mm)

P (

kN/m

m)

9.7

10.7

11.7

12.7

13.8

14.8

15.8

16.8

17.8

18.8

PMT P-y Curves Pascagoula

Page 38: Manual Fbpier

P-Y Curves from DMT 1Pascagoula, Mississippi

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

0 10 20 30 40 50 60

p (mm)

y (k

N/m

m)

9.610.811.712.616.016.917.8

DMT P-y Curves Pascagoula

Page 39: Manual Fbpier

Pascagoula Predictions

0

500

1000

1500

2000

2500

3000

3500

4000

4500

0 10 20 30 40 50

Deflection (mm)

Lo

ad (

kN) DMT

PMT

Actual

Page 40: Manual Fbpier

Instrumentation & Measurements

• Strain gages– Measure strain– Calculate bending moment, M = ε(EI/c), if EI

of section known– “high tech”

• Slope inclinometer– Measures slope– Relatively “low tech”

Page 41: Manual Fbpier

Theoretical Pile Behavior

PM

Pile

Y(z)

Deflection

Y’(z)

Slope

M(z)

Moment

M’(z)

Shear

P(z)

Soil Reaction

Page 42: Manual Fbpier

Strain Gages Bending Moment

Page 43: Manual Fbpier

Bending Moment versus Depth

0

1

2

3

4

5

6

0 200 400 600 800 1000 1200

Bending Moment (kN*m)

Dep

th (

m) 36

62

93

121

153

182

211

258

LateralLoad in Kilonewtons

Page 44: Manual Fbpier

Bending Moment vs. Depth

PM

Pile

Y(z)

Deflection

Y’(z)

Slope

M(z)

Moment

M’(z)

Shear

P(z)

Soil Reaction

Page 45: Manual Fbpier

Two Integrals to Deflection

PM

Pile

Y(z)

Deflection

Y’(z)

Slope

M(z)

Moment

M’(z)

Shear

P(z)

Soil Reaction

Page 46: Manual Fbpier

Two Derivatives to Load

PM

Pile

Y(z)

Deflection

Y’(z)

Slope

M(z)

Moment

M’(z)

Shear

P(z)

Soil Reaction

z

z

Page 47: Manual Fbpier

Non-linear Concrete ModelTest Pile T1

0.0E+00

2.0E+05

4.0E+05

6.0E+05

8.0E+05

1.0E+06

0.0E+00 2.0E-03 4.0E-03 6.0E-03 8.0E-03 1.0E-02Curvature, (1/m)

EI (

kN-m

2 )

Page 48: Manual Fbpier

P-y Curves from Strain Gages

0

20

40

60

80

100

120

140

0 5 10 15 20 25 30 35

Displacement, y (mm)

p (k

N/m

)

1.0

2.0

3.0

4.1

D. to G.S.(m)

Page 49: Manual Fbpier

Slope Inclinometer Slope

Page 50: Manual Fbpier

Deflection versus Depth

-2

0

2

4

6

8

10

-0.01 0.00 0.01 0.02 0.03 0.04 0.05 0.06 0.07

Horizontal Displacement (m)

De

pth

(m

)

36

62

90

122

153

183

208

243

Lateral Load in Kilonewtons

Page 51: Manual Fbpier

Slope Inclinometer → Slope vs. Depth

PM

Pile

Y(z)

Deflection

Y’(z)

Slope

M(z)

Moment

M’(z)

Shear

P(z)

Soil Reaction

Page 52: Manual Fbpier

One Integral to Deflection

PM

Pile

Y(z)

Deflection

Y’(z)

Slope

M(z)

Moment

M’(z)

Shear

P(z)

Soil Reaction

Page 53: Manual Fbpier

Three Derivatives to Load

PM

Pile

Y(z)

Deflection

Y’(z)

Slope

M(z)

Moment

M’(z)

Shear

P(z)

Soil Reaction

z

z

z

Page 54: Manual Fbpier

P-y Curves from Slope Inclinometer

0

20

40

60

80

100

120

140

0 5 10 15 20 25 30 35

Displacement, y (mm)

p (k

N/m

)

1.0

2.0

3.0

4.0

D. to GS(m)

Page 55: Manual Fbpier

0

20

40

60

80

0 5 10 15 20 25 30 35

Displacement, y (mm)

p (k

N/m

)

SGincPMT/DMTSPT

Comparison of P-y Curves

Page 56: Manual Fbpier

Prediction of Pile Top Deflection

0

50

100

150

200

250

300

0 20 40 60 80 100

Top Displacement (mm)

Lo

ad

(kN

)

W. line

FLPIER-sg

FLPIER-inc

Page 57: Manual Fbpier

P-y Curves Available in FB-Pier

• Standard– Sand

• O’Neill

• Reese, Cox, & Koop

– Clay• O’Neill

• Matlock Soft Clay Below Water Table

• Reese Stiff Clay Below Water Table

• Reese & Welch Stiff Clay Above Water Table

Page 58: Manual Fbpier

P-y Curves Available in FB-Pier

• User Defined– Pressuremeter– Dilatometer– Instrumentation

• Strain Gages

• Slope Inclinometer

Page 59: Manual Fbpier

Session Outline

• Identify and Discuss Soil-Pile Interaction Models– Precast & Cast Insitu Axial T-Z & Q-Z Models– Torsional - Models– Lateral P-Y Models– Nonlinear Pile Structural Models

• FB-MultiPier Input and Output– Example #1 Single Pile

Page 60: Manual Fbpier

Pile Discrete Element Modelh h2

h2

X

Z

X

Y

(Top View)

(Side View)

M M

M M

1 3

2 4

U n iv e r s a l J o in t

Rigid center-blocks

Rigid end Block

Spring

Page 61: Manual Fbpier

Curvature-Strain-Stress-Moment

a) Strain due to

z-axis bendingb) Strain due to

y-axis bendingc) Strain due to

axial thrust

NN

F

,

F

,i

i

1

2

x

y

z

dF

dA

i

i

e) Stress-strain relationshipd) Combined strains

Page 62: Manual Fbpier

Stress-Strain Curves for Concrete & Steel

Page 63: Manual Fbpier

Strains -> Stress -> Moments

x

y

z

dF

dA

i

i

d) Combined strains

dFi=i*dAi

n_PointsIntegratio

x ydF*M

Page 64: Manual Fbpier

Stiffness of Cross-Section: Flexure, Axial

M

x

y

z

dF

dA

i

i

d) Combined strains

n_PointsIntegratio

x ydF*M

Page 65: Manual Fbpier

Failure Ratio Calculation

My

Mx

P

Mx

o

Myo

Pactua

l

Failure Ratio = Surface

Length

Actual Length

Page 66: Manual Fbpier

Pile Material Properties

Page 67: Manual Fbpier

References:• Robertson, P. K., Campanella, R. G., Brown, P. T., Grof, I., and Hughes, J. M., "Design of

Axially and Laterally Loaded Piles Using In Situ Tests: A Case History,“ Canadian Geotechnical Journal, Vol. 22, No. 4, pp.518-527, 1985.

• Robertson, P. K., Davies, M. P., and Campanella, R. G., "Design of Laterally Loaded Driven Piles Using the Flat Dilatometer," Geotechnical Testing Journal, GTJODJ, Vol. 12, No. 1, pp. 30-38, March 1989.

• Reese, L. C., Cox, W. R. and Koop, F. D (1974). "Analysis of Laterally Loaded Piles in Sand," Paper No. OTC 2080, Proceedings, Fifth Annual Offshore Technology Conference, Houston, Texas, (GESA Report No. D-75-9).

• Hoit, M.I, McVay, M., Hays, C., Andrade, P. (1996). “Nonlinear Pile Foundation Analysis Using Florida Pier." Journal of Bridge Engineering. ASCE. Vol. 1, No. 4, pp.135-142.

• Randolph, M. and Wroth, C., 1978, “Analysis of Deformation of Vertically Loaded Piles, ASCE Journal of Geotechnical Engineering, Vol. 104, No. 12, pp. 1465-1488.

• Matlock, H., and Reese, L., 1960, “Generalized Solutions for Laterally Loaded Piles,” ASCE, Journal of Soil Mechanics and Foundations Division, Vol. 86, No. SM5, pp. 63-91.

Page 68: Manual Fbpier

Session Outline

• Identify and Discuss Soil-Pile Interaction Models– Precast & Cast Insitu Axial T-Z & Q-Z Models– Torsional - Models– Lateral P-Y Models– Nonlinear Pile Structural Models

• FB-MultiPier Input and Output– Example #1 Single Pile