1. Computer Program DFSAP Deep Foundation System Analysis Program Based on Strain Wedge Method
Prepared by
J. P. Singh & Associates
in association with
Mohamed Ashour, Ph.D., PE
West Virginia University Tech
and
Gary Norris Ph.D., PE
University of Nevada, Reno
APRIL 3/4, 2006

2. WORK PROGRESS PHASE I PHASE II S-SHAFT PROGRAM FOR SHORT SHAFTS
ONE-ROW SHAFT GROUP (AVE. SHAFT)
SHAFT CAP (for one row of shafts)
SOIL LIQUEFACTION
PHASE II
INTERMEDIATE / LONG PILE/SHAFT
SHAFT/PILE GROUP
ISOLATED SHAFT AND SHAFT GROUP
IN LIQUEFIABLE SOIL
LATERAL SOIL SPREAD
PILES/SHAFTS IN SLOPING GROUND
ROTATION & DISPLACEMENT FOUNDATION STIFFNESSES (K11, K22, )

3. PRESENTATION PROGRAM
Comparison between Current Practice and the Strain Wedge Model Technique Used in Program DFSAP
Soil Liquefaction and Anticipated Lateral Spread, and their Effect on Pile/Shaft Response
Short/Intermediate/Long Pile/Shaft in Liquefied & Nonliquefied Soil Profiles, and Pile Cap Effect
Axially Loaded Piles and Piles in Sloping Ground
Linear and Nonlinear Equivalent Stiffness Matrix for Bridge Foundations
DFSAP Program Demonstration (Input and Output Data)

4. Transverse Longitudinal Z X K11 K22 K66 Y Foundation Springs in
the Longitudinal Direction
K11
K22
K66
Column Nodes
Longitudinal

5. Laterally Loaded Pile as a Beam on Elastic Foundation (BEF)1 3 4 2 5 Mo Po Pv
Laterally Loaded Pile as a Beam
on Elastic Foundation (BEF)

6. DIFFERENCES BETWEEN THE TRADITIONAL P-Y CURVE AND PROGRAM DFSAP
Traditional p-y Curve Does Not Account for the Following:
Pile Bending Stiffness (EI)
Pile Head Conditions (Free/Fixed)
Pile Cross-Section Shape (Square/Circular/H-Shape)
Pile-Head Embedment Below Ground
Soil Profile Continuity (Winkler Springs)
It was developed for Long Piles
Empirical Parameters
Soil Liquefaction and Lateral Soil Spread
Pile Group
Vertical Side Shear Resistances
(Large Diameter Shaft)

7. Effect of Structure Cross-Sectional
Shape on Soil Reaction P K1 K2
4 ft
Laterally Loaded Pile as a Beam
on Elastic Foundation (BEF)

8. Footing Kr = L As presented by Terzaghi (1955) and Vesic (1961)
q per unit area B C L q
0.5q
Kr = 
Kr = 0
Rigid Footing, Kr = 
Flexible Footing, Kr = 0
Footing H
(1-2s) EP H3
6 (1-2P) Es B3
Kr =
As presented by Terzaghi (1955) and Vesic (1961)
Effect of the Footing Flexural Rigidity (EI) on
the Distribution of the Soil Reaction

9. Wedge Model Analysis Based on the Strain
The traditional p-y curve (in LPILE) does
not account for the pile/shaft EI variation EI
0.1 EI
Wedge Model Analysis
Based on the Strain

10. Kim et al. (ASCE J., 2004)

11. LARGE DIAMETER SHAFT Mo Pv Mo Po Pv Po FP Fv Mt Ft Vt D u z T y p S o- h a f t H r n R e s c D u N g d w L Po Mo Pv

12. The Basic Strain Wedge Model in Uniform Soil
Ashour and Norris
UNR
SAND
CLAY
C-
ROCK
The Basic Strain Wedge Model in Uniform Soil

13. C Pile B F1  p x h m Pile A m
Mobilized zones as
assessed experimentally m
Pile
Pile head
load Po
Successive mobilized
wedges
(c) Forces at the face of the soil passive wedge
(Section elevation A-A) m
Pile
Real stressed zone F1
No shear stress because
these are principle stresses ds dx 
h
h * CD* dx = * CD * ds sin m A
VO
Side shear () that
influences the oval
shape of the stressed zone
(b) Force equilibrium in a slice of the wedge at depth x m
KVO p Yo h x Hi i
i-1
Sublayer i+1
Sublayer 1 
Plane taken to simplify
analysis (i.e. F1’s cancel) C B
Fig. 5 Relationship between the real Mobilized stress
zones and the SW model passive wedges

14. Pile/Shaft Nonlinear Material Modeling
Stress
Strain f s g y
Yield Stress (f ) so E
Uniaxial Elastic-Perfectly Plastic
Numerical Steel Model f cc E c g cu
Compressive Strain,
Compressive stress, f
Stress-Strain Model for Confined
Concrete in Compression

15. Validation Example
(Chapter 6)

16. UCLA TEST

18. Shaft Head Response at the UCLA Test

19. 2-ft-Diameter Free-Head Shaft Response at the UCLA Test
Shaft Length = 25 ft (Bridge Conference, Oct. 2005)

20. PILE GROUP

21. PILE GROUP p y psingle pgroup = fm psinglePo Pv
PILE GROUP
P-multiplier (fm) concept for pile group
(Brown et al. 1988) y p
pgroup = fm psingle
psingle
Pile in a group
Single pile

22. PILE GROUP
Configuration of the Mobilized Passive Wedges, and Associated Pile Group Interference

24. (Po)g Horizontal passive wedge interference in pile group response
Overlap of stresses based on elastic theory
(and nonuniform shaped deflection at pile face)
Overlap employed in SW model based on
uniform stress and pile face deflection
(Po)g
Uniform pile
face movement
Horizontal passive wedge interference in pile group response

25. Validation Examples
(Report, Chapter 6)
Lateral response of pile-group (P vs. Yo)
Response of individual piles in a group
p-y curves of individual piles

26. Morrison and Reese Pile Group Test in Sands (1986)

28. Validation Example
(Report, Chapter 6)
Limitations of traditional p-y curves
Lateral response of isolated shaft
and shaft-group
Vertical shear side resistance effect on
diameter shafts

29. Shaft B1
Shaft B2
The Taiwan Test by Brown et al. 2001

30. In order to match the measured data using LPILE, the traditional
p-y curves were modified as shown above (Brown et al. 2001)

31. 40 80
120
160
200 P i l e H a d D f c t o n , Y m
1000
2000
3000
4000 L k N M s u r ( B w . 2 1 ) S W V h g 5 -
Shaft
(B1) F

33. (Treasure Island Test)
Validation Example
(Treasure Island Test)
Validation of pile classification in DFSAP
Response of individual piles in a group

35. Treasure Island 3 x 3 Pile Group Test (Rollins et al. , ASCE J. , No

36. (Rollins et al. 2005, ASCE Journal)

37. Validation Example Report, Chapter 5
3 x 3 Pile group in soil Profile-S5 from WSDOT
Design Manual
Pile Cap Contribution
Pile-head effect (free and fixed)

38. Loading Direction

39. 3 x 3 SHAFT GROUP OF 2-FT LENGTH IN SOIL PROFILE S-7
FREE-HEAD, EXAMPLE 2

40. 3 x 3 SHAFT GROUP OF 2-FT LENGTH IN SOIL PROFILE S-7
FIXED-HEAD, EXAMPLE 2

41. FREE-HEAD
FIXED-HEAD

42. QUESTIONS ????