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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.

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Presentation on theme: "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."— Presentation transcript:

1 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 Computer Program DFSAP Deep Foundation System Analysis Program Based on Strain Wedge Method

2 PHASE I S-SHAFT PROGRAM FOR SHORT SHAFTS ONE-ROW SHAFT GROUP (AVE. SHAFT) SHAFT CAP (for one row of shafts) SOIL LIQUEFACTION WORK PROGRESS 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  Linear and Nonlinear Equivalent Stiffness Matrix for Bridge Foundations 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  DFSAP Program Demonstration (Input and Output Data)  Axially Loaded Piles and Piles in Sloping Ground

4 Y XX Z Z Y Foundation Springs in the Longitudinal Direction K 11 K 22 K 66 Column Nodes Longitudinal Transverse

5 y p (E s ) 1 (E s ) 3 (E s ) 4 (E s ) 2 p p p y y y (E s ) 5 p y MoMo PoPo PvPv Laterally Loaded Pile as a Beam on Elastic Foundation (BEF)

6 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) DIFFERENCES BETWEEN THE TRADITIONAL P-Y CURVE AND PROGRAM DFSAP

7 Laterally Loaded Pile as a Beam on Elastic Foundation (BEF) P P K1K1 K2K2 4 ft Effect of Structure Cross-Sectional Shape on Soil Reaction

8 Effect of the Footing Flexural Rigidity (EI) on the Distribution of the Soil Reaction q per unit area B C L q 0.5q K r =  K r = 0 Rigid Footing, K r =  Flexible Footing, K r = 0 Footing H (1- 2 s ) E P H 3 6 (1- 2 P ) E s B 3 K r = As presented by Terzaghi (1955) and Vesic (1961)

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

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

11 LARGE DIAMETER SHAFT

12 The Basic Strain Wedge Model in Uniform Soil SAND CLAY C-  ROCK

13 Fig. 5 Relationship between the real Mobilized stress zones and the SW model passive wedges Mobilized zones as assessed experimentally mm Pile Pile head load P o Successive mobilized wedges mm

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

15 Validation Example (Chapter 6)

16 UCLA TEST

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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 PoPo PvPv P-multiplier (f m ) concept for pile group (Brown et al. 1988) y p p group = f m p single p single Pile in a group Single pile

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

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24 Horizontal passive wedge interference in pile group response Pile 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 (P o ) g Uniform pile face movement

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

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

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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 Pile Head Deflection, Y o, mm P i l e H e a d L o a d, P o, k N Measured (Brown et al. 2001) Predicted (SW Model) No V. Side Shear With V. Side Shear Single 1.5-m-Diameter Shaft (B1) Free-head

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

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35 Treasure Island 3 x 3 Pile Group Test (Rollins et al., ASCE J., No. 1, 2005)

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 FIXED-HEADFREE-HEAD

42 QUESTIONS ????

43


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