A Technique for Selecting Appropriate Allowable Pile Loads ... · A Technique for Selecting...

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A Technique for Selecting Appropriate

Allowable Pile Loads for Driven-Pile

Projects: Load Matching

Wagner Komurka Geotechnical Group, Inc.

Pile Driving Contractors Association

2015 Professor’s Driven Pile Institute

June 25, 2015

Van E. Komurka, P.E., D.GE, F.ASCE

2

• Load-Matching Evaluations – Philosophy

– Define Optimum Allowable Pile Load

– Case Histories

• Medium/Large

• Small

Talk Outline

• Support Cost – Define

– Pile Support Cost • Based on Available Support

• Based on Utilized Support

3



– Case Histories

• Medium/Large

• Small

Talk Outline




4

Pile Support Cost: Design Efficiency

Installed Cost = $5,000

Allowable Pile Load = 250T

Structure Design

Load = 700T

Structure Design

Load = 300T

$5,000

250T

Large Resisted Loads Small Resisted Loads

3 x $5,000

700T

3 x $5,000

300T $20.00 per available ton

=

$50.00 per structure

design ton

$21.43 per structure

design ton

= =

Based on Available Support Based on Utilized Support

5



– Case Histories

• Medium/Large

• Small

Talk Outline




6

Load-Matching Evaluation – Match Allowable

Pile Loads to Column Loads!

Piles are below-grade structural extensions of above-

grade structural elements; their design should be

integrated with the above-grade design.

Using one allowable pile load for a project is

analogous to using one beam or column design

throughout a building.

Two fixed design components:

Structural loads to support (column load schedule).

Soil/pile resistance behavior to support structural

loads (depth vs. capacity relationships).

Deep foundation system design flexibility (choice of pile

type, section, allowable load, construction-control

method, safety factor, etc.) allows optimally matching

fixed design components.

7



– Case Histories

• Medium/Large

• Small

Talk Outline




8

Optimum Allowable Pile Load

Column Design Load

Minimum Req’d No. of Piles

900K

=

Load Matching Evaluation

9

Minimum Required Number of Piles

Minimum 3 Piles

Required

Minimum 2 Piles

Required

Minimum 1 Pile

Required?

10

Optimum Allowable Pile Load

Column Design Load

Minimum Req’d No. of Piles

Column Design Load = 900 kips

Minimum Req’d No. of Piles = 3

Optimum Allowable Pile Load =

900 kips

3 piles

= 300 kips/pile = 150 tons/pile

900K

=

11

Lower-Than-Optimum Allowable Pile Loads

Increased pile support costs – each ton of allowable

pile load costs more than it would have with higher-

allowable-load piles.

Increased cap support costs – each cap is larger than

it would have been with higher-allowable-load piles;

may increase excavation/material disposal costs,

utility relocation costs.

Increased number of pile installations. May increase

total project drive time, construction control

monitoring costs.

12

Higher-Than-Optimum Allowable Pile Loads

Unused capacity installed – although pile support costs

are low, and cap costs are minimized, unnecessary

capacity is installed (unnecessary cost is incurred).

13



– Case Histories

• Medium/Large

• Small

Talk Outline




14

Load-Matching Design Approach

Obtain foundation layout, column load schedule, and

the minimum required number of piles at each cap,

from structural engineer.

Calculate optimum allowable pile load for each cap.

If desired, calculate required “ultimate” pile capacity

for each cap. To evaluate the cost-effectiveness of

field testing, this can be done for a range of factors

of safety.

17

F.S. = 2.00

Maximum

Optimum Required

Allowable "Ultimate"

Column Min. Column Pile Pile

Line No. Load, Load, Capacity,

Designation of Piles kips tons tons

0.A-8.5 1 158 79 158

0.A-0.5 1 180 90 180

P-3.3 1 181 91 181

P-3.7 1 181 91 181

P-4.5 1 181 91 181

P-5 1 181 91 181

P-5.5 1 181 91 181

P-6 1 181 91 181

0.A-8 1 203 102 203

M.5-8 1 228 114 228

N-8.5 1 360 180 360

P.7-8.5 1 360 180 360

P-0.5 1 360 180 360

P-8.5 1 360 180 360

Q.8-3 1 360 180 360

Q-0.5 1 360 180 360

M.5-4 1 368 184 368

J-5 2 748 187 374

G-7 3 1479 247 493

H-7 3 1479 247 493

K-6 3 1484 247 495

B-7 3 1487 248 496

B-6 3 1507 251 502

C-8 3 1508 251 503

R1-5.9 3 1510 252 503

K-7 3 1529 255 510

C-4 3 1874 312 625

F-6 3 1879 313 626

J-6 3 1942 324 647

J-4 3 1995 333 665

Q-9 3 2003 334 668

R-9 3 2003 334 668

448

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an indication of the minimum required number of

piles at each cap, from structural engineer.


Calculate required “ultimate” pile capacity for each

cap. To evaluate the cost-effectiveness of field

testing, this can be done for a range of factors of

safety.

Generate histogram of optimum allowable pile loads.

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91

ton

s

18

0 ton

s

19

4 ton

s 22

7 ton

s

0

10

20

30

40

50

60

70

75 100 125 150 175 200 225 250 275 300 325 350 375

Allowable Pile Load Histogram N

um

ber

of

Piles

Optimum Allowable Pile Load, tons

20



an indication of the minimum required number of

piles at each cap, from structural engineer.


Calculate required ultimate pile capacity for each

cap. To evaluate the cost-effectiveness of field

testing, this can be done for a range of factors of

safety.

Generate histogram of optimum allowable pile loads.

Select appropriate allowable pile loads, with design-

team input.

21

91

ton

s

18

0 ton

s

19

4 to

ns 22

7 to

ns

0

10

20

30

40

50

60

70

75 100 125 150 175 200 225 250 275 300 325 350 375


um

ber

of

Piles


180 tons 251 tons 91 tons

22

0

5

10

15

20

25

30

0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170

Nu

mb

er

of

Pil

es

Optimum Allowable Axial Compression Pile Load, tons

Number of Piles vs. Optimum Allowable Axial Compression Pile Load

48 Tons 113 Tons

For Comparison - Different Case History

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Load-Matching Design Approach (continued)

Select viable pile type(s) and section(s) for selected

allowable loads (91T, 180T, and 251T). {borings}

Estimate individual pile lengths required for selected

pile capacities.

24

-110

-100

-90

-80

-70

-60

-50

-40

-30

-20

-10

0

10

0 100 200 300 400 500 600 700

Estimated Ultimate Pile Capacity - Borings 13.375-Inch-Diameter Pipe Piles

Pile T

oe E

levati

on

, fe

et

Estimated “Ultimate” Pile Capacity, tons

25

-130

-120

-110

-100

-90

-80

-70

-60

-50

-40

-30

-20

-10

0

10

0 50 100 150 200 250 300 350

Estimated “Ultimate” Capacity, tons

Pil

e T

oe

Ele

va

tio

n, fe

et

Pile Test

Program

Results -

Capacity

Profiles Long-term

Capacity

EOID

Capacity

Set-Up

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allowable pile loads (91T, 180T, 251T).


pile capacities.

Estimate total pile lengths required for project.

Using representative prices, estimate total pile cost

for project.

27


um

ber

of

Piles


91

to

ns

18

0 ton

s

19

4 to

ns

22

7 ton

s

0

10

20

30

40

50

60

70

75 100 125 150 175 200 225 250 275 300 325 350 375

180 tons 251 tons

91 tons

28

F.S. = 2.00

Maximum

Optimum Required


Column Min. Column Pile Pile Est. Pile Est. Pile(s) Est. Pile(s)

Line No. Load, Load, Capacity, No. Length, Footage, Cost,

Designation of Piles kips tons tons of Piles feet feet dollars

0.A-8.5 1 158 79 158 1 62 62 1,340

0.A-0.5 1 180 90 180 1 62 62 1,340

P-3.3 1 181 91 181 1 62 62 1,340 91-ton max.

P-3.7 1 181 91 181 1 62 62 1,340 allow. load:

P-4.5 1 181 91 181 1 62 62 1,340 71

P-5 1 181 91 181 1 62 62 1,340 10.75x0.365

P-5.5 1 181 91 181 1 62 62 1,340 feet:

P-6 1 181 91 181 1 62 62 1,340 4,402

0.A-8 1 203 102 203 1 86 86 2,405

M.5-8 1 228 114 228 1 86 86 2,405

N-8.5 1 360 180 360 1 86 86 2,405 180-ton max.

P.7-8.5 1 360 180 360 1 86 86 2,405 allow. load:

P-0.5 1 360 180 360 1 86 86 2,405 108

P-8.5 1 360 180 360 1 86 86 2,405 13-3/8" 0.480

Q.8-3 1 360 180 360 1 86 86 2,405 feet:

Q-0.5 1 360 180 360 1 86 86 2,405 9,288

M.5-4 1 368 184 368 1 95 95 2,657

J-5 2 748 187 374 2 95 190 5,314

G-7 3 1479 247 493 3 95 285 7,971 251-ton max.

H-7 3 1479 247 493 3 95 285 7,971 allow. load:

K-6 3 1484 247 495 3 95 285 7,971 177

B-7 3 1487 248 496 3 95 285 7,971 13-3/8" 0.480

B-6 3 1507 251 502 3 95 285 7,971 feet:

C-8 3 1508 251 503 3 95 285 7,971 16,815

R1-5.9 3 1510 252 503 4 95 380 10,629

K-7 3 1529 255 510 4 95 380 10,629

C-4 3 1874 312 625 4 95 380 10,629 251-ton max.

F-6 3 1879 313 626 4 95 380 10,629 allow. load:

J-6 3 1942 324 647 4 95 380 10,629 125

J-4 3 1995 333 665 4 95 380 10,629 13-3/8" 0.480

Q-9 3 2003 334 668 4 95 380 10,629 feet:

R-9 3 2003 334 668 4 95 380 10,629 11,875

448 481 42,380 $1,157,416

3 Capacities (91, 180, and 251 tons)

$21.61 / ft

$27.97 / ft

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allowable pile loads (91T, 180T, 251T).


pile capacities.

Calculate total pile lengths required for project.

Calculate total pile cost for project.

Perform additional iterations as desired.

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F.S. = 2.00

Maximum

Optimum Required


Column Min. Column Pile Pile Est. Pile Est. Pile(s) Est. Pile(s) Est. Pile Est. Pile(s) Est. Pile(s)

Line No. Load, Load, Capacity, No. Length, Footage, Cost, Number Length, Footage, Cost,

Designation of Piles kips tons tons of Piles feet feet dollars of Piles feet feet dollars

0.A-8.5 1 158 79 158 1 62 62 1,340 2 58 116 2,223

0.A-0.5 1 180 90 180 1 62 62 1,340 2 58 116 2,223

P-3.3 1 181 91 181 1 62 62 1,340 91-ton max. 2 58 116 2,223

P-3.7 1 181 91 181 1 62 62 1,340 allow. load: 2 58 116 2,223

P-4.5 1 181 91 181 1 62 62 1,340 71 2 58 116 2,223

P-5 1 181 91 181 1 62 62 1,340 10.75x0.365 2 58 116 2,223

P-5.5 1 181 91 181 1 62 62 1,340 feet: 2 58 116 2,223

P-6 1 181 91 181 1 62 62 1,340 4,402 2 58 116 2,223

0.A-8 1 203 102 203 1 86 86 2,405 2 58 116 2,223

M.5-8 1 228 114 228 1 86 86 2,405 2 58 116 2,223

N-8.5 1 360 180 360 1 86 86 2,405 180-ton max. 3 58 174 3,334

P.7-8.5 1 360 180 360 1 86 86 2,405 allow. load: 3 58 174 3,334

P-0.5 1 360 180 360 1 86 86 2,405 108 3 58 174 3,334

P-8.5 1 360 180 360 1 86 86 2,405 13-3/8" 0.480 3 58 174 3,334

Q.8-3 1 360 180 360 1 86 86 2,405 feet: 3 58 174 3,334

Q-0.5 1 360 180 360 1 86 86 2,405 9,288 3 58 174 3,334

M.5-4 1 368 184 368 1 95 95 2,657 3 58 174 3,334

J-5 2 748 187 374 2 95 190 5,314 6 58 348 6,668

G-7 3 1479 247 493 3 95 285 7,971 251-ton max. 12 58 696 13,335

H-7 3 1479 247 493 3 95 285 7,971 allow. load: 12 58 696 13,335

K-6 3 1484 247 495 3 95 285 7,971 177 12 58 696 13,335

B-7 3 1487 248 496 3 95 285 7,971 13-3/8" 0.480 12 58 696 13,335

B-6 3 1507 251 502 3 95 285 7,971 feet: 12 58 696 13,335

C-8 3 1508 251 503 3 95 285 7,971 16,815 12 58 696 13,335

R1-5.9 3 1510 252 503 4 95 380 10,629 12 58 696 13,335

K-7 3 1529 255 510 4 95 380 10,629 13 58 754 14,447

C-4 3 1874 312 625 4 95 380 10,629 251-ton max. 15 58 870 16,669

F-6 3 1879 313 626 4 95 380 10,629 allow. load: 15 58 870 16,669

J-6 3 1942 324 647 4 95 380 10,629 125 16 58 928 17,780

J-4 3 1995 333 665 4 95 380 10,629 13-3/8" 0.480 16 58 928 17,780

Q-9 3 2003 334 668 4 95 380 10,629 feet: 16 58 928 17,780

R-9 3 2003 334 668 4 95 380 10,629 11,875 16 58 928 17,780

448 481 42,380 $1,157,416 1,560 90,480 $1,733,597

$576,181

3 Capacities (91, 180, and 251 tons) 1 Capacity (10.75 x 0.188, 63 tons)

$19.16 / ft

$21.61 / ft

$27.97 / ft

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F.S. = 2.00

Maximum

Optimum Required


Column Min. Column Pile Pile Est. Pile Est. Pile(s) Est. Pile(s) Est. Pile Est. Pile(s) Est. Pile(s)

Line No. Load, Load, Capacity, No. Length, Footage, Cost, Number Length, Footage, Cost,

Designation of Piles kips tons tons of Piles feet feet dollars of Piles feet feet dollars

0.A-8.5 1 158 79 158 1 62 62 1,340 2 58 116 2,223

0.A-0.5 1 180 90 180 1 62 62 1,340 2 58 116 2,223

P-3.3 1 181 91 181 1 62 62 1,340 91-ton max. 2 58 116 2,223

P-3.7 1 181 91 181 1 62 62 1,340 allow. load: 2 58 116 2,223

P-4.5 1 181 91 181 1 62 62 1,340 71 2 58 116 2,223

P-5 1 181 91 181 1 62 62 1,340 10.75x0.365 2 58 116 2,223

P-5.5 1 181 91 181 1 62 62 1,340 feet: 2 58 116 2,223

P-6 1 181 91 181 1 62 62 1,340 4,402 2 58 116 2,223

0.A-8 1 203 102 203 1 86 86 2,405 2 58 116 2,223

M.5-8 1 228 114 228 1 86 86 2,405 2 58 116 2,223

N-8.5 1 360 180 360 1 86 86 2,405 180-ton max. 3 58 174 3,334

P.7-8.5 1 360 180 360 1 86 86 2,405 allow. load: 3 58 174 3,334

P-0.5 1 360 180 360 1 86 86 2,405 108 3 58 174 3,334

P-8.5 1 360 180 360 1 86 86 2,405 13-3/8" 0.480 3 58 174 3,334

Q.8-3 1 360 180 360 1 86 86 2,405 feet: 3 58 174 3,334

Q-0.5 1 360 180 360 1 86 86 2,405 9,288 3 58 174 3,334

M.5-4 1 368 184 368 1 95 95 2,657 3 58 174 3,334

J-5 2 748 187 374 2 95 190 5,314 6 58 348 6,668

G-7 3 1479 247 493 3 95 285 7,971 251-ton max. 12 58 696 13,335

H-7 3 1479 247 493 3 95 285 7,971 allow. load: 12 58 696 13,335

K-6 3 1484 247 495 3 95 285 7,971 177 12 58 696 13,335

B-7 3 1487 248 496 3 95 285 7,971 13-3/8" 0.480 12 58 696 13,335

B-6 3 1507 251 502 3 95 285 7,971 feet: 12 58 696 13,335

C-8 3 1508 251 503 3 95 285 7,971 16,815 12 58 696 13,335

R1-5.9 3 1510 252 503 4 95 380 10,629 12 58 696 13,335

K-7 3 1529 255 510 4 95 380 10,629 13 58 754 14,447

C-4 3 1874 312 625 4 95 380 10,629 251-ton max. 15 58 870 16,669

F-6 3 1879 313 626 4 95 380 10,629 allow. load: 15 58 870 16,669

J-6 3 1942 324 647 4 95 380 10,629 125 16 58 928 17,780

J-4 3 1995 333 665 4 95 380 10,629 13-3/8" 0.480 16 58 928 17,780

Q-9 3 2003 334 668 4 95 380 10,629 feet: 16 58 928 17,780

R-9 3 2003 334 668 4 95 380 10,629 11,875 16 58 928 17,780

448 481 42,380 $1,157,416 1,560 90,480 $1,733,597

$576,181

3 Capacities (91, 180, and 251 tons) 1 Capacity (10.75 x 0.188, 63 tons)

$19.16 / ft

$21.61 / ft

$27.97 / ft

32



– Case Histories

• Medium/Large

• Small

Talk Outline




33

Condominiums

Relatively small project, approximately 200 piles

required.

Renovation of a former storage warehouse into

condominiums.

Piles required only beneath small building addition.

Existing geotechnical engineering report prepared

for different site development plans.

A review of existing recommendations relative to

currently proposed development was desired.

34

36

42

50

5

4

72

10

8

12

5

12

9

21

5

0

5

10

15

20

25

30

30 50 70 90 110 130 150 170 190 210

Nu

mb

er

of

Piles


Optimum Allowable Pile Load Histogram Condominiums

35

Condominiums - Proposed Designs

Allowable Number Estimated

Design Load, tons of Piles Footage

Original 70 205 15,580

36

36

42

50

5

4

72

10

8

12

5

12

9

21

5

0

5

10

15

20

25

30

30 50 70 90 110 130 150 170 190 210

Nu

mb

er

of

Piles



37




Original 70 205 15,580

Revised 72 180 14,040

SAVE: 25 1,540

$34,250 + cap costs

on $346,500 worth of piles

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Original 70 205 15,580

Revised 72 180 14,040

Alternate 100 130 $60,000 savings

72 tons per pile x 180 piles = 12,960 tons to support

12,960 tons / 100 tons per pile = 130 piles

Save 50 piles & $60,000 ?

39

36

42

50

5

4

72

10

8

12

5

12

9

21

5

0

5

10

15

20

25

30

30 50 70 90 110 130 150 170 190 210

Nu

mb

er

of

Piles



40

216-ton

column load

216-ton

column load



41




Original 70 205 15,580

Revised 72 180 14,040

Alternate 100 164 15,744

SAVE: 16 (not 50) -1,704

($37,897) (if same pile section is used)

42

Conclusions

• Consider using higher-capacity piles (when building

loads warrant)

• Consider matching (optimizing) allowable pile loads to

column loads

• All should result in more-cost-effective driven-pile

foundations

• Evaluate design options/alternatives using actual

column loads and allowable pile load histogram

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Questions / Comments?

A Technique for Selecting Appropriate Allowable Pile Loads ... · A Technique for Selecting...

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