1. AASHTO LRFD Section 10. 7 and 10
AASHTO LRFD Section 10.7 and Deep Foundations “BY FAR THIS SECTION HAS BEEN IDENTIFIED AS THE MOST PROBLEMATIC SECTION OF THE AASHTO LRFD SPECS. BY THE STATE DOTS”

2. 10.7 DRIVEN PILES
General
MINIMUM PILE SPACING, CLEARANCE AND EMBEDMENT INTO CAP
PILES THROUGH EMBANKMENT FILL
BATTER PILES
PILE DESIGN REQUIREMENTS
Determination of Pile Loads
Downdrag
Uplift Due to Expansive Soils
Nearby Structures
Service Limit State Design
GENERAL
TOLERABLE MOVEMENTS
settlement
Pile Groups in Cohesive Soil
Pile Groups in Cohesionless Soil
HORIZONTAL PILE FOUNDATION MOVEMENT
SETTLEMENT DUE TO DOWNDRAG
lateral squeeze
Strength Limit State Design
POINT BEARING PILES ON ROCK
Piles Driven to Soft Rock
Piles Driven to Hard Rock
pile length estimates for contract documents
nominal axial RESISTANCE CHANGE AFTER PILE DRIVING
Relaxation
Setup
groundwater effects and BUOYANCY

3. Deep Foundations Overview
10.7 Driven Piles
Total re-write
10.8 Drilled Shafts
Re-organized + new & updated content

4. Service Limit State (10.7.2) Vertical Displacement
Additional equivalent footing diagrams added
Horizontal Displacement
P-y method for analysis of horizontal displacement now specifically called out
P multipliers for group effects updated and specified
Overall stability

5. Vertical Displacement

6. Horizontal Displacement (P-y method)Qt P Ht Mt y y
Properties
A, E, I y

7. S P P
Original curve
Modified curve
Pm * P y D
P-multiplier (Pm)
Spacing (S)
Row 1
Row 2
Row 3 3D
0.7
0.5
0.35 5D
1.0
0.85
From Table

8. Overall Stability

9. Strength Limit State (10.7.3)
Geotechnical Resistance
Emphasis of pile resistance verification during construction
De-emphasis on use of static analysis methods except for estimation of pile length for contract drawings
Structural Resistance
Axial
Combined bending and axial
Shear
Driven Resistance (10.7.7)

10. Axial Geotechnical Resistance

11. Static Load Test

12. Load
Elastic pile compression
Settlement
Pile top settlement
Davidson Method Specified

13. Dynamic Load Test (PDA)
Method & equations are now prescribed

14. Driving Formulas

15. Driving Formulas FHWA Gates Method Method & Equation Prescribed
Engineering News Method
Equation Modified to Produce Ultimate Resistance by Removing the Built-in Factor of Safety = 6

16. Driving Formula Limitations
Design “stresses” must be limited if a driveability analysis is not performed
limiting stresses prescribed
Limited to nominal resistances below 300 tons

17. Geotechnical Safety Factors for Piles
Design Basis & Const. Control
Increasing Design/Const. Control
Subsurface Expl.
X X X X X
Static Calculation
Dynamic Formula X
Wave Equation
X X X X
CAPWAP
X X
Static Load Test
X X FS

18. Static Analysis Methods
Existing Methods Retained
FHWA Nordland/Thurman Method Added
Applicability limited to:
- Prediction of pile penetration (used without resistance factors)
- Rare case of driving to prescribed penetration or depth (no field determination of pile axial resistance)

19. Geotechnical Resistance Factors Pile Static Analysis Methods
Comp
Ten
 - Method
0.4
0.3
 - Method
0.35
0.25
 - Method
Nordlund-Thurman
0.45
SPT
CPT
Group
0.6
0.5
Note that the static analysis resistance factors are much less than the field tested resistance factors.
Ask Participants why (answer less uncertainty from fielded tested resistance)
From Table

20. CONDITION/RESISTANCE DETERMINATION METHOD
Table Resistance Factors for Driven Piles
CONDITION/RESISTANCE DETERMINATION METHOD
RESISTANCE FACTOR
Nominal Resistance of Single Pile in Axial Compression – Dynamic Analysis and Static Load Test Methods, dyn
Driving criteria established by static load test(s); quality control by dynamic testing and/or calibrated wave equation, or minimum driving resistance combined with minimum delivered hammer energy from the load test(s). For the last case, the hammer used for the test pile(s) shall be used for the production piles.
Values in Table 2
Driving criteria established by dynamic test with signal matching at beginning of redrive conditions only of at least one production pile per pier, but no less than the number of tests per site provided in Table 3. Quality control of remaining piles by calibrated wave equation and/or dynamic testing.
0.65
Wave equation analysis, without pile dynamic measurements or load test, at end of drive conditions only
0.40
FHWA-modified Gates dynamic pile formula (End Of Drive condition only)
Engineering News Record (as defined in Article ) dynamic pile formula (End Of Drive condition only)
0.10

21. Number of Static Load Tests per Site
Table Relationship between Number of Static Load Tests Conducted per Site and  (after Paikowsky, et al., 2004)
Number of Static Load Tests per Site
Resistance Factor, 
Site Variability*
Low*
Medium*
High* 1
0.80
0.70
0.55 2
0.90
0.75
0.65 3
0.85
> 4

22. Number of Piles Located within Site
Table Number of Dynamic Tests with Signal Matching Analysis per Site to Be Conducted During Production Pile Driving (after Paikowsky, et al., 2004)
Site Variability*
Low*
Medium*
High*
Number of Piles Located within Site
Number of Piles with Dynamic Tests and Signal Matching Analysis Required (BOR)
< 15 3 4 6
16-25 5 8
26-50 9
51-100 7 10 12
> 500

23. Structural Axial Failure Mode

24. Structural Flexure Failure Mode

25. Structural Shear Failure Mode

26. Methods for determining structural resistance
Axial compression
Combined axial and flexure
Shear
LRFD
Specifications
Concrete – Section 5
Steel – Section 6
Wood – Section 8

27. Driven Performance Limit

28. Drivability Analysis (10.7.7)
Specifically required
Purpose is to verify that the specified pile can be driven:
To the required minimum penetration
To the required ultimate resistance
Using a commonly available hammer
Without exceeding the permissible driving stress
At a reasonable penetration rate

29. 37.5 ksi
550 kip
120 bpf

30. Driven Performance Limit

31. Extreme Event Limit State (10.7.4 )
New section with limited guidance regarding extreme events (no guidance previously provided)

32. Piles - Other Considerations
Corrosion and Deterioration
Moved from section with no major changes
Determination of Minimum Pile Penetration
New section combining some of the existing material from section with additional guidance.
Downdrag provisions extensively modified

33. Drilled shafts, O’Neill and Reese (1999)
Downdrag
New provisions in article regarding determination of downdrag as a load
Revisions to load factors pending additional analysis/research
Prediction Method
Maximum
Minimum
Piles, -Tomlinson
1.4 -
Piles, -Method
1.05
Drilled shafts, O’Neill and Reese (1999)
1.25

34. 10.8 DRILLED SHAFTS Article re-organized to follow section 10.7
Most provisions refer back to section 10.7
Service limit state provisions removed from strength limit state resistance determination
Provisions for resistance determination updated
Detailed procedures for evaluation of combined side friction and end bearing in rock added to commentary

35. 10.8 DRILLED SHAFTS
General
scope
shaft spacing, clearance and embedment into cap
shaft diameter and enlarged bases
batterED shafts
drilled SHAFT resistance
DETERMINATION OF Shaft Loads
General
Downdrag
Uplift
Service Limit State Design
tolerable movements
settlement
General
Settlement of Single-Drilled Shaft
Intermediate Geo Materials (IGM’s)
Group Settlement
HORIZONTAL MOVEMENT OF SHAFTS AND SHAFT GROUPS
settlement due to downdrag
lateral squeeze
Strength Limit State Design
general
ground water table and bouyancy
Scour
downdrag
NOMINAL axial COMPRESSION resistance of single drilled shafts
Estimation of Drilled Shaft Resistance in Cohesive Soils
a Side Resistance
b Tip Resistance
Estimation of Drilled Shaft Resistance in Cohesionless Soils

36. Drilled Shaft Resistance in Rock
Total Resistance A
Side Resistance B
Resistance D C
Tip Resistance QS
Displacement
QR = fQn = fqpQp + fqsQs QP

37. Geotechnical Resistance Factors Drilled Shafts
Method
Comp
Ten
 - Method (side)
0.55
0.45
 - Method (side)
Clay or Sand (tip)
0.5
Rock (side)
Rock (tip)
Group (sand or clay)
Load Test
0.7
The resistance factors are provided for each method in AASHTO section 10.5
AASHTO Table