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

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,.......)

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)

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

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)

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)

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

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

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

Kim et al. (ASCE J., 2004)

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

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

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

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

Validation Example (Chapter 6)

UCLA TEST

Shaft Head Response at the UCLA Test

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

PILE GROUP

PILE GROUP p y psingle pgroup = fm psingle Po 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

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

(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

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

Morrison and Reese Pile Group Test in Sands (1986)

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

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

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

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

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

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

(Rollins et al. 2005, ASCE Journal)

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)

Loading Direction

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

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

FREE-HEAD FIXED-HEAD

QUESTIONS ????