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DFI Electric Power Systems Foundations Working Group Utility Survey Questions

First Name: Last Name: Company Name: Work Phone: Email Address: City: State/Province: Country:

A. Demographics

1. Please select your engineering discipline.

☐ Civil☐ Geotechnical☐ Structural☐ Electrical☐ Other: _______________________

2. What is your level of engineering experience with foundation design?

☐ 0-5yrs☐ 5-10yrs☐ 10-20yrs☐ 20+yrs

3. Are you a registered professional engineer?

☐ Yes ☐ No

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B. Deep Foundation Design Approach

4. What code(s) do you use for load development? (Mark all that apply)

☐ NESC☐ CAS☐ C22.3☐ GO95

Other (Please describe below):

5. What additional load cases outside of the legislated loads per referenced codes do youuse? (Mark all that apply)

☐ Local climate☐ Construction☐ Maintenance☐ Security

Other (Please describe below):

6. Do you utilize an internal design manual for deep foundation design?

☐ Yes ☐ No

7. If yes, do you use an internal design manual, what foundation types are covered?

☐ Drilled shafts ☐ Driven piles ☐ Micropiles ☐ Helical piles ☐ ACP/CFA Piles ☐ Other _________________________

8. Would you be willing to provide a copy of the design manual to this working group for internalreview?

☐ Yes ☐ No

9. What type of deep foundation design methodology do you use?

☐ RBD – Reliability Based Design☐ ASD – Allowable Stress Design

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C. Deep Foundation Design Practices

10. Please list the magnitudes of the load factors and/or safety factors you use for deep foundationdesign.

☐ From 1.0 to 2.0☐ > 2.0☐ Electric code factors☐ RBD factors☐ Do not use factors, deflection controls☐ Other

Other (Please describe below):

11. Do you use the same magnitudes of load or safety factors for foundation construction materials,such as reinforced concrete or steel?

☐ Yes ☐ No

12. If no, please indicate how these factors differ.

☐ Lower than used for foundation depth/diameter design ☐ Higher than used for foundation depth/diameter design ☐ Not applicable ☐ Other

Other (Please describe below):

13. What foundation deflection criteria do you use for tubular steel poles?

inches ☐ A specified value of☐ A specified range of☐ V aries by foundation diameter☐ N one

Other (Please describe below):

inches

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14. What foundation rotation criteria do you use for tubular steel poles?

degrees ☐ A specified value of☐ A specified range of☐ None

Other (Please describe below):

15. What axial maximum movement criteria do you use for lattice towers (uplift and/or compression)?

inches ☐ A specified value of☐ A specified range of☐ V aries by foundation diameter☐ N one

Other (Please describe below):

16. How were these deflection criteria determined?

☐ In house standards☐ Past/historical performance☐ Experience☐ Consultant recommendations☐ Published information

Other (Please describe below):

17. Under what load condition is deflection and/or rotation evaluated?

☐ Factored loads☐ Service loads

Other (Please describe below):

degrees

inches

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18. Do you integrate the drilled pier deflection/rotation criteria with the similar allowable criteria for thetop of steel poles for the pole manufacturer?

☐ Yes ☐ No

If yes, please describe how, e.g., do you assume a total maximum top of pole deflection and splitthis up between the foundation and pole allowable?

19. What software and version do you use to design your deep foundations - poles and towers?(Mark all that apply)

☐ EPRI FAD Tools ☐ Ensoft LPile ☐ Ensoft Group ☐ Shaft Caisson ☐ AllPile

Other (Please describe below):

20. What is the typical height of foundation projection above grade do you assume?

feet ☐ A specified value of☐ A specified range of☐ V aries by location☐ N one

Other (Please describe below):

21. Do you assume any soil property discount (reduction) for near surface soils?

☐ Yes ☐ No

feet

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22. How are the effects of reduced soil capacity for foundations on/near slopes accounted in design?

☐ Diameter based☐ Equivalent ground method☐ Specified depth☐ Part of the design model☐ Varies☐ Not taken into consideration☐ Not known

Other (Please describe below):

23. How are water flow impacts such as scour accounted in design?

☐ Add reveal☐ Value recommended by consultant☐ Perform an engineering evaluation☐ Install protection (no modification to foundation)☐ Not included in design☐ Unknown / not applicable

Other (Please describe below):

24. Do you design foundations for liquefaction effects?

☐ Yes ☐ No

If yes, what is your engineering approach?

☐ Add reinforcement☐ Recommendations by consultant☐ Perform an engineering evaluation☐ Unknown

Other (Please describe below):

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D. Geotechnical Exploration Practices

25. What types of geotechnical exploration techniques do you use to obtain foundation design parameters? (Mark all that apply)

☐ Desktop studies ☐ Borings ☐ Cone penetrometer tests ☐ Geophysical investigations, rock cores

Other (Please describe below):

26. Please describe the data on which you base your geotechnical design, e.g., do you generally obtain site specific geotechnical data for every structure, do you develop a generalized geotechnical design strata based upon limited borings, or other?

☐ Sample every structure ☐ Sample one per mile ☐ Sample at critical structures ☐ Geologic-based sampling ☐ Varies

Other (Please describe below):

27. What is the basis for determining spacing between a limited number of borings?

☐ Structure-based ☐ Mileage-based ☐ Geology-based

Other (Please describe below):

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28. Do you require a soil corrosivity analysis?

☐ Yes ☐ No

If no, do you employ a standard practice for soil corrosivity?

☐ Coat direct embedment steel☐ Modify cement type in backfill☐ Use general site knowledge☐ Not applicable; Unknown☐ None

Other (Please describe below):

29. Do you assume a minimum embedment into bedrock?

☐ Yes ☐ No

If yes, what is that embedment?

☐ A specified value of feet☐ A specified depth in terms of pier diameter

If not, how do you determine rock socket depth?

E. Reinforced Concrete Design Practices

30. Is the concrete strength used for construction higher than assumed in design?

☐ Yes ☐ No

31. Do you have specific concrete mix design that you require the contractor to use?

☐ Yes ☐ No

If Yes (Please describe below);

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32. What design methodology do you use to determine the minimum longitudinal reinforcing?

☐ Minimum steel ☐ Codes (ACI, CSA, etc.) ☐ Computer program results ☐ Other

Other (Please describe below):

33. What methods are used for anchor bolt design?

☐ ASCE 48; CSA A23.3 ☐ Vendor supplies this information ☐ ACI ☐ Not Applicable ☐ Unknown

34. Recognizing that ACI 318 states it does not apply to drilled shafts, what code or methodology do you use for reinforcement design?

☐ Highway drilled shaft methods ☐ ACI or modified ACI methods ☐ CSA A23.3 methods ☐ Computer program ☐ Varies ☐ Not applicable

35. What provisions do you use for splicing of vertical reinforcement?

☐ ACI 318 ☐ CRSI ☐ FHWA

Other (Please describe below):

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F. Direct Embedment Pole Design Practices

36. What type of material is specified for backfill? (Mark all that apply)

☐ Compacted native soil ☐ Engineering aggregate fill ☐ Concrete

Other (Please describe below):

37. What design parameters are used in your design methodology for the backfill? (Mark all that apply)

☐ Friction angle ☐ Cohesion; unit weight ☐ Deformation modulus

Other (Please describe below):

38. Are pole embedment based on analytical methods or general practice methods (10% + 2' or 4') for design? (Mark all that apply)

☐ Analytical methods ☐ General practice methods

Other (Please describe below):

G. Alternate Deep Foundations

39. Do you allow the use of deep foundation alternates to drilled shafts or direct embeds (such as micropiles, auger cast piles or helical anchor foundations)?

☐ Yes ☐ No

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40. Do you have foundation specifications for specific alternate foundation types?

☐ Yes ☐ No

41. What types of foundation specifications for specific alternate foundation types do you have? (Mark all that apply)

☐ Drilled shafts ☐ Driven piles ☐ Micropiles ☐ Helical piles ☐ ACP/CFA

Other (Please describe below):

H. Foundation Field Testing and Validation

42. Do you have specific testing requirements to validate installed foundation capacity (i.e., proof or ultimate testing)?

☐ Yes ☐ No

If yes, what type of testing do you require? ☐ Compression ☐ Tension ☐ Lateral ☐ Combined

Other (Please describe below):

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I. Foundation Construction Considerations

43. Do you have limitations on free fall of placed concrete?

☐ Yes ☐ No

If yes, please describe:

44. What procedures or requirements do you have for the use of cold or construction joints with drilled shaft foundations?

☐ Not allowed ☐ Joints placed at a design-defined depth ☐ Joints placed at a designated depth

Other (Please describe below):