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Analysis of Laterally Loaded Drilled Shafts and Piles Using LPILE Shin-Tower Wang, Ph.D., P.E. Ensoft, Inc./Lymon C. Reese & Associates Austin, Texas April 3, 2009
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Analysis of Laterally Loaded Drilled Shafts and Piles Using LPILE Shin-Tower Wang, Ph.D., P.E. Ensoft, Inc./Lymon C. Reese & Associates Austin, Texas April.

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Page 1: Analysis of Laterally Loaded Drilled Shafts and Piles Using LPILE Shin-Tower Wang, Ph.D., P.E. Ensoft, Inc./Lymon C. Reese & Associates Austin, Texas April.

Analysis of Laterally Loaded Drilled Shafts and Piles Using

LPILE

Shin-Tower Wang, Ph.D., P.E. Ensoft, Inc./Lymon C. Reese &

AssociatesAustin, Texas

April 3, 2009

Page 2: Analysis of Laterally Loaded Drilled Shafts and Piles Using LPILE Shin-Tower Wang, Ph.D., P.E. Ensoft, Inc./Lymon C. Reese & Associates Austin, Texas April.

Outlines Introduction Basic theory of the p-y curve method

Numerical solution for soil-structure interaction

Characteristic Shape of p-y Curves Available p-y Curve Criteria Common Input Values

Special consideration for large-diameter piers Effect of nonlinear EI on deflection Special features in LPILE

Page 3: Analysis of Laterally Loaded Drilled Shafts and Piles Using LPILE Shin-Tower Wang, Ph.D., P.E. Ensoft, Inc./Lymon C. Reese & Associates Austin, Texas April.

Piles are used in a variety of ways to support super-structures

Page 4: Analysis of Laterally Loaded Drilled Shafts and Piles Using LPILE Shin-Tower Wang, Ph.D., P.E. Ensoft, Inc./Lymon C. Reese & Associates Austin, Texas April.

Drilled Shafts with Lateral Load

PM

Q

Ultimate earth pressure

(strength fully mobilized)

Actual earth pressure

Ultimate earth pressure

(strength fully mobilized)

Actual earth pressure

Page 5: Analysis of Laterally Loaded Drilled Shafts and Piles Using LPILE Shin-Tower Wang, Ph.D., P.E. Ensoft, Inc./Lymon C. Reese & Associates Austin, Texas April.

Methods of Solution

Linearly elastic solution (Poulos and Davis, 1980) emphasizes the condition of continuity although the soil cannot be characterized as a linearly elastic material.

Limit-equilibrium solution (Broms, 1965)

finds the ultimate lateral load at failure, but soil-structure interaction at lesser loads is not addressed.

The p-y method with beam-column model (McClelland, Matlock, Reese, 1958-1975)

has been developed extensively to take into account the soil-structure interaction and nonlinear resistance of soils.

3-D Finite-Element method

Page 6: Analysis of Laterally Loaded Drilled Shafts and Piles Using LPILE Shin-Tower Wang, Ph.D., P.E. Ensoft, Inc./Lymon C. Reese & Associates Austin, Texas April.

Soil Failure Patterns

Wedge Failure

Plane-Strain Failure

Page 7: Analysis of Laterally Loaded Drilled Shafts and Piles Using LPILE Shin-Tower Wang, Ph.D., P.E. Ensoft, Inc./Lymon C. Reese & Associates Austin, Texas April.
Page 8: Analysis of Laterally Loaded Drilled Shafts and Piles Using LPILE Shin-Tower Wang, Ph.D., P.E. Ensoft, Inc./Lymon C. Reese & Associates Austin, Texas April.
Page 9: Analysis of Laterally Loaded Drilled Shafts and Piles Using LPILE Shin-Tower Wang, Ph.D., P.E. Ensoft, Inc./Lymon C. Reese & Associates Austin, Texas April.

Nonlinear Model for Lateral Soil Resistance

Page 10: Analysis of Laterally Loaded Drilled Shafts and Piles Using LPILE Shin-Tower Wang, Ph.D., P.E. Ensoft, Inc./Lymon C. Reese & Associates Austin, Texas April.

EI = pile stiffnessy = pile deflectionx = distance along pilePx = axial load on pile andEpy = slope of secant to p-y curve at point on pileW = distributed lateral loading

02

2

4

4

WyEdx

ydP

dx

ydEI pyx

Differential Equation

Page 11: Analysis of Laterally Loaded Drilled Shafts and Piles Using LPILE Shin-Tower Wang, Ph.D., P.E. Ensoft, Inc./Lymon C. Reese & Associates Austin, Texas April.

Illustration of Numerical Solution Procedure

Epy

x

p

yV

y

p

Epy

Page 12: Analysis of Laterally Loaded Drilled Shafts and Piles Using LPILE Shin-Tower Wang, Ph.D., P.E. Ensoft, Inc./Lymon C. Reese & Associates Austin, Texas April.
Page 13: Analysis of Laterally Loaded Drilled Shafts and Piles Using LPILE Shin-Tower Wang, Ph.D., P.E. Ensoft, Inc./Lymon C. Reese & Associates Austin, Texas April.

p-y Curves Developed From Static-Load Tests on24-in. Diameter Pile.

Page 14: Analysis of Laterally Loaded Drilled Shafts and Piles Using LPILE Shin-Tower Wang, Ph.D., P.E. Ensoft, Inc./Lymon C. Reese & Associates Austin, Texas April.

Characteristic Shape of p-y Curves

a. Initial Linear-elastic section

b. Transition from linear to nonlinear section

c. Yield section into limit state or plasticity failure

a.

b.

c.

Page 15: Analysis of Laterally Loaded Drilled Shafts and Piles Using LPILE Shin-Tower Wang, Ph.D., P.E. Ensoft, Inc./Lymon C. Reese & Associates Austin, Texas April.

p-y Curve Criteria Soft Clay (Matlock, 1970) Stiff Clay

(1). with free water (Reese et al., 1975) (2). Without free water (Reese & Welch, 1975)

Sand (Reese model & API Model) Liquefied Sand (Rollins et al., 2005) c- Soil (Evans and Duncan*, 1982) Strong Rock (Reese & Nyman, 1978) Weak Rock (Reese, 1997)

(* Concept only, not the full model)

Page 16: Analysis of Laterally Loaded Drilled Shafts and Piles Using LPILE Shin-Tower Wang, Ph.D., P.E. Ensoft, Inc./Lymon C. Reese & Associates Austin, Texas April.

Common Input Values Effective Unit Weight Shear Strength

Cohesion, c Friction Angle,

Soil Stiffness, 50

Initial Stiffness of p-y Curve, k Rock Properties, RQD, qu, etc.

Page 17: Analysis of Laterally Loaded Drilled Shafts and Piles Using LPILE Shin-Tower Wang, Ph.D., P.E. Ensoft, Inc./Lymon C. Reese & Associates Austin, Texas April.

Soft Clay

Static Loading

Cyclic Loading

Page 18: Analysis of Laterally Loaded Drilled Shafts and Piles Using LPILE Shin-Tower Wang, Ph.D., P.E. Ensoft, Inc./Lymon C. Reese & Associates Austin, Texas April.

Stiff Clay with Free Water

Static Loading

Cyclic Loading

Page 19: Analysis of Laterally Loaded Drilled Shafts and Piles Using LPILE Shin-Tower Wang, Ph.D., P.E. Ensoft, Inc./Lymon C. Reese & Associates Austin, Texas April.

Stiff Clay without Free Water

Static Loading Cyclic Loading

Page 20: Analysis of Laterally Loaded Drilled Shafts and Piles Using LPILE Shin-Tower Wang, Ph.D., P.E. Ensoft, Inc./Lymon C. Reese & Associates Austin, Texas April.

Sand (Reese Criteria)

Static & Cyclic Coefficients

Page 21: Analysis of Laterally Loaded Drilled Shafts and Piles Using LPILE Shin-Tower Wang, Ph.D., P.E. Ensoft, Inc./Lymon C. Reese & Associates Austin, Texas April.

Liquefied Sand (Rollins et al.)

Rollins model is limited to relative densitiesBetween 45 and 55 percent

Pile diameter = 324 mm

Page 22: Analysis of Laterally Loaded Drilled Shafts and Piles Using LPILE Shin-Tower Wang, Ph.D., P.E. Ensoft, Inc./Lymon C. Reese & Associates Austin, Texas April.

Cemented c- Soil

Use of this p-y curve is not recommended without a load test to establish k

y

p

b/60 3b/80

m

uym

yu

pm

pu

ks

k pk

yk

Pult=Pu( ) + Pu ( c )

Page 23: Analysis of Laterally Loaded Drilled Shafts and Piles Using LPILE Shin-Tower Wang, Ph.D., P.E. Ensoft, Inc./Lymon C. Reese & Associates Austin, Texas April.

Vuggy Limestone

y

p

0.0004b

pu = b su

Es = 2000su

Perform proof test if deflection is in this range

Assume brittle fracture if deflection is in this range

Es = 100su

NOT TO SCALE

0.0024b

Page 24: Analysis of Laterally Loaded Drilled Shafts and Piles Using LPILE Shin-Tower Wang, Ph.D., P.E. Ensoft, Inc./Lymon C. Reese & Associates Austin, Texas April.

Weak Rock

y

p

A

pur

Required rock propertiesUniaxial Compressive Strength, su (from lab tests)RQD (from field investigation records)Rock Mass Modulus (interpreted)krm (from lab tests or estimated)Effective Unit Weight (from lab tests)

Kir

ya

Page 25: Analysis of Laterally Loaded Drilled Shafts and Piles Using LPILE Shin-Tower Wang, Ph.D., P.E. Ensoft, Inc./Lymon C. Reese & Associates Austin, Texas April.

Soil Layering Effects

Georgiadis’ Method for Equivalent Depth (1983)

Page 26: Analysis of Laterally Loaded Drilled Shafts and Piles Using LPILE Shin-Tower Wang, Ph.D., P.E. Ensoft, Inc./Lymon C. Reese & Associates Austin, Texas April.

Georgiadis’ Method for Equivalent Depth (1983)

Page 27: Analysis of Laterally Loaded Drilled Shafts and Piles Using LPILE Shin-Tower Wang, Ph.D., P.E. Ensoft, Inc./Lymon C. Reese & Associates Austin, Texas April.

Pile-Head Conditions:Shear and Moment

Mt

Pt

Qt

Note: Origin of Coordinate System for Pile and Soil Layers is Located at the Pile Head

Layer 1

Layer 2

Layer 3

Pile Length

Distance to Ground Surface

Page 28: Analysis of Laterally Loaded Drilled Shafts and Piles Using LPILE Shin-Tower Wang, Ph.D., P.E. Ensoft, Inc./Lymon C. Reese & Associates Austin, Texas April.

Pile-Head Conditions:Displacement and Slope

Qt

Note: Origin of Coordinate System for Pile and Soil Layers is Located at the Pile Head

Layer 1

Layer 2

Layer 3

Pile Length

Distance to Ground Surface yt

t

Page 29: Analysis of Laterally Loaded Drilled Shafts and Piles Using LPILE Shin-Tower Wang, Ph.D., P.E. Ensoft, Inc./Lymon C. Reese & Associates Austin, Texas April.

Effect of Side Friction and Tip Resistance on Large-Diameter Piers

Contact friction, Fs

Tip rotation bearing, Fb

Contact friction (maybe small)

B

H

Fs

0.2”

Tip rotation bearing, Fb

(need large mobilization)

Fb

0.05B

M

Page 30: Analysis of Laterally Loaded Drilled Shafts and Piles Using LPILE Shin-Tower Wang, Ph.D., P.E. Ensoft, Inc./Lymon C. Reese & Associates Austin, Texas April.

Size Effect

1. For linear elastic portion of the p-y curves the size effect is not significant on initial k values.

2. For ultimate soil resistance Pu is a function of the pile diameter.

3. Most correlation coefficients in current p-y criteria were derived based on pile diameter of 2 ft to 4 ft.

Page 31: Analysis of Laterally Loaded Drilled Shafts and Piles Using LPILE Shin-Tower Wang, Ph.D., P.E. Ensoft, Inc./Lymon C. Reese & Associates Austin, Texas April.
Page 32: Analysis of Laterally Loaded Drilled Shafts and Piles Using LPILE Shin-Tower Wang, Ph.D., P.E. Ensoft, Inc./Lymon C. Reese & Associates Austin, Texas April.

Using service load to check deflection criteria

Using factored load to check bending moment and shear

Page 33: Analysis of Laterally Loaded Drilled Shafts and Piles Using LPILE Shin-Tower Wang, Ph.D., P.E. Ensoft, Inc./Lymon C. Reese & Associates Austin, Texas April.

Uncrack/Crack EI’s

Page 34: Analysis of Laterally Loaded Drilled Shafts and Piles Using LPILE Shin-Tower Wang, Ph.D., P.E. Ensoft, Inc./Lymon C. Reese & Associates Austin, Texas April.

Effect of Nonlinear EI on Deflection

Comparison of pile-head deflections computed for same load using elastic and nonlinear EI values.

It is possible to under-predict pile-head deflections if only elastic EI values are used.

Page 35: Analysis of Laterally Loaded Drilled Shafts and Piles Using LPILE Shin-Tower Wang, Ph.D., P.E. Ensoft, Inc./Lymon C. Reese & Associates Austin, Texas April.

Top Deflection vs. LengthTop Deflection vs. Embedment Depth

LPILE Plus 5.0, (c) 2004 by Ensoft, Inc.

Embedment Depth, meters121110987

Top D

efle

ctio

n, m

0.05

0.045

0.04

0.035

0.03

0.025

0.02

0.015

0.01

0.005

0

Page 36: Analysis of Laterally Loaded Drilled Shafts and Piles Using LPILE Shin-Tower Wang, Ph.D., P.E. Ensoft, Inc./Lymon C. Reese & Associates Austin, Texas April.

Pile Subjected to Lateral Spreading due to Liquefaction of Soils

Page 37: Analysis of Laterally Loaded Drilled Shafts and Piles Using LPILE Shin-Tower Wang, Ph.D., P.E. Ensoft, Inc./Lymon C. Reese & Associates Austin, Texas April.
Page 38: Analysis of Laterally Loaded Drilled Shafts and Piles Using LPILE Shin-Tower Wang, Ph.D., P.E. Ensoft, Inc./Lymon C. Reese & Associates Austin, Texas April.

Slope Stabilized by Drilled Shafts

Fs is derived from p-y curves

Page 39: Analysis of Laterally Loaded Drilled Shafts and Piles Using LPILE Shin-Tower Wang, Ph.D., P.E. Ensoft, Inc./Lymon C. Reese & Associates Austin, Texas April.

Adjust the Passive Earth Pressure Not Over The Bending Capacity

Page 40: Analysis of Laterally Loaded Drilled Shafts and Piles Using LPILE Shin-Tower Wang, Ph.D., P.E. Ensoft, Inc./Lymon C. Reese & Associates Austin, Texas April.

Slope-Stability Analysis with Resistance from vertical piles

Page 41: Analysis of Laterally Loaded Drilled Shafts and Piles Using LPILE Shin-Tower Wang, Ph.D., P.E. Ensoft, Inc./Lymon C. Reese & Associates Austin, Texas April.

Main Window for LRFD

Load CombosUnfactored LoadsFactored Loads

Page 42: Analysis of Laterally Loaded Drilled Shafts and Piles Using LPILE Shin-Tower Wang, Ph.D., P.E. Ensoft, Inc./Lymon C. Reese & Associates Austin, Texas April.

Unfactored Load Definitions

Page 43: Analysis of Laterally Loaded Drilled Shafts and Piles Using LPILE Shin-Tower Wang, Ph.D., P.E. Ensoft, Inc./Lymon C. Reese & Associates Austin, Texas April.

Load Factors, Resistance Factors, and Combinations

Page 44: Analysis of Laterally Loaded Drilled Shafts and Piles Using LPILE Shin-Tower Wang, Ph.D., P.E. Ensoft, Inc./Lymon C. Reese & Associates Austin, Texas April.

Load Summary Report (1)

Page 45: Analysis of Laterally Loaded Drilled Shafts and Piles Using LPILE Shin-Tower Wang, Ph.D., P.E. Ensoft, Inc./Lymon C. Reese & Associates Austin, Texas April.

Load Summary Report (3)

Page 46: Analysis of Laterally Loaded Drilled Shafts and Piles Using LPILE Shin-Tower Wang, Ph.D., P.E. Ensoft, Inc./Lymon C. Reese & Associates Austin, Texas April.
Page 47: Analysis of Laterally Loaded Drilled Shafts and Piles Using LPILE Shin-Tower Wang, Ph.D., P.E. Ensoft, Inc./Lymon C. Reese & Associates Austin, Texas April.
Page 48: Analysis of Laterally Loaded Drilled Shafts and Piles Using LPILE Shin-Tower Wang, Ph.D., P.E. Ensoft, Inc./Lymon C. Reese & Associates Austin, Texas April.

Concrete Properties

Page 49: Analysis of Laterally Loaded Drilled Shafts and Piles Using LPILE Shin-Tower Wang, Ph.D., P.E. Ensoft, Inc./Lymon C. Reese & Associates Austin, Texas April.

Reinforcing Bar Properties

Warning messagefor cage spacingand percent steel

Bar bundling options

Page 50: Analysis of Laterally Loaded Drilled Shafts and Piles Using LPILE Shin-Tower Wang, Ph.D., P.E. Ensoft, Inc./Lymon C. Reese & Associates Austin, Texas April.

Recent Publications by Others Using LPILE

Rollins, K.M., Peterson, K.T., and Weaver, T.J.,”Lateral Load Behavior of Full-Scale Pile Group in Clay”, J. Geotech. & GeoEnviro. Eng. ASCE Vol 124, No.6, June, 1988. Anderson, J.B., Townsend, F.C., and Grajales, B.,”Case History Evaluation of Laterally Loaded Piles”, J. Geotech. & GeoEnvir. Eng. ASCE Vol 129, No.3, March, 2003. Davidson, W.A, McCabe, R.J., and Soydemir, C.,”Below Boston’s new Bridge”, Civil Engineering, Dec. 1998.

Page 51: Analysis of Laterally Loaded Drilled Shafts and Piles Using LPILE Shin-Tower Wang, Ph.D., P.E. Ensoft, Inc./Lymon C. Reese & Associates Austin, Texas April.

Thank You