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. PILE CAP EFFECT AND PILE DEFLECTION PATTERNS IN THE PROGRAM DFSAP

3. SINGLE SHAFT FOUNDATION FOUNDATION CUT-OFF SECTION SHAFT GROUP WITH CAP (X) (Z) (X) FOUNDATION CUT-OFF SECTION Fig. 2-1 General Axis of Bridge and Bridge Foundations

4. y Cap Passive Wedge Pile Passive Wedges Pile/Shaft Group with Cap

5. P2P2 K 22 K 11 K 66 P1P1 M3M3 Y Y XX P2P2 K 22 K 33 K 44 P3P3 M1M1 Y Y ZZ A) Loading in the Longitudinal Direction (Axis 1 or X Axis ) B) Loading in the Transversal Direction (Axis 3 or Z Axis ) Single Shaft

6. Pile Cap T v PoPo o MoMo PvPv y K face KVKV KHKH Piles/Shafts

7. Loading Direction

8. Piles + Cap Piles Cap 320 Piles + Cap Piles Cap 410 Free-HeadFixed-Head Effect of Pile-Head Conditions on Cap Resistance at the Same Deflection Value in DFSAP

9. h = 0.69 X o XoXo Zero Crossing X o > h > 0.69 X o XoXo Zero Crossing h = X o Deflection Pattern Linearized Deflection YoYo YoYo YoYo    Deflection Pattern Long Shaft L/T  4 Intermediate Shaft 4 > L/T > 2 Short Shaft L/T  2  L = SHAFT LENGTH T = (EI/f ) 0.2 f = Coefficient. of Modulus of Subgrade Reaction Varying Deflection Patterns Based on Shaft Type

11. Type of Shaft Analysis vs. Shaft Response

12. T PoPo MoMo PvPv y 65 ft 6 ft P v = 100 kip P o = 150 kip M o = 800 kip-ft L/T = 2.5 Intermediate Shaft Soil Profile – S5 Short Shaft Analysis Intermediate Analysis

13. T PoPo MoMo PvPv y 75 ft 6 ft P v = 100 kip P o = 150 kip M o = 800 kip-ft L/T = 3.1 Intermediate Shaft Soil Profile – S5 Short Shaft Analysis Intermediate Analysis Short Shaft Analysis Intermediate Analysis

14. T PoPo MoMo PvPv y 90 ft 6 ft P v = 100 kip P o = 150 kip M o = 800 kip-ft L/T = 4.0 Long Shaft Soil Profile – S5 Short Shaft Analysis Long Shaft Analysis

15. 3x 3 Shaft Group with Cap 6-ft-diameter shafts

16. 3 x 3 6-ft-Diameter Shaft Group/Cap in Soil Profile – S5

18. 3 x 3 SHAFT GROUP IN SOIL PROFILE S-5 Shaft Length = 55 ft, Diameter = 6 ft

19. 3 x 3 SHAFT GROUP OF 55-FT LENGTH AND 6-FT-THICK CAP IN SOIL PROFILE S-5

20. Soil Liquefaction on Shaft Response in DFSAP Program

21. T PoPo MoMo PvPv y 55 ft 6 ft P v = 100 kip P o = 800 kip M o = 3000 kip-ft M EQ = 6.0 Soil Profile – S7 Liquefaction DFSAP

22. T PoPo MoMo PvPv y 65 ft 6 ft P v = 100 kip P o = 800 kip M o = 3000 kip-ft M EQ = 6.0 Soil Profile – S7 Liquefaction DFSAP

23. T PoPo o MoMo PvPv y 90 ft 6 ft P v = 100 kip P o = 800 kip M o = 3000 kip-ft M EQ = 6.0 Soil Profile – S7 Liquefaction DFSAP

24. Effect of Shaft Length and Soil Layers on the p-y Curve at Certain Depth

25. T PoPo MoMo PvPv y L 6 ft Soil Profile – S5 1 Shaft-Length Effect on the p-y Curve P-y Curve at 5 ft depth P-y Curve at 20 ft depth

26. T PoPo MoMo PvPv y 65 ft 6 ft Soil Profile – S7 Liquefaction 2 Effect of Soil Profile (Liquefaction) on the p-y Curve at the Same Depth.

27. 6-FT-DIAMETER SHAFT IN SOIL PROFILE – S7

28. Conclusions: The pile cap should be analyzed as a part of the foundation system and is a affected by pile-head stiffness. The deflection mechanism (short/intermediate/long) of pile governs the interaction between the pile and soil (i.e. pile stiffness) The p-y curve at a particular depth is not unique and varies based on the type of pile/shaft (short/intermediate/long) The p-y curve at a particular depth is affected by the changes of the properties of the overlying and underlying soil layers.