a technique for selecting appropriate allowable pile loads ... · a technique for selecting...
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1
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
• 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
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
• 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
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
• 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
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
• 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
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.
15
16
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
18
Load-Matching Design Approach
Obtain foundation layout, column load schedule, and
an indication of the minimum required number of
piles at each cap, from structural engineer.
Calculate optimum allowable pile load for each cap.
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.
19
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
Load-Matching Design Approach
Obtain foundation layout, column load schedule, and
an indication of the minimum required number of
piles at each cap, from structural engineer.
Calculate optimum allowable pile load for each cap.
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
Allowable Pile Load Histogram N
um
ber
of
Piles
Optimum Allowable Pile Load, tons
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
23
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
26
Load-Matching Design Approach (continued)
Select viable pile type(s) and section(s) for selected
allowable pile loads (91T, 180T, 251T).
Estimate individual pile lengths required for selected
pile capacities.
Estimate total pile lengths required for project.
Using representative prices, estimate total pile cost
for project.
27
Allowable Pile Load Histogram N
um
ber
of
Piles
Optimum Allowable Pile Load, tons
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
Allowable "Ultimate"
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
29
Load-Matching Design Approach (continued)
Select viable pile type(s) and section(s) for selected
allowable pile loads (91T, 180T, 251T).
Estimate individual pile lengths required for selected
pile capacities.
Calculate total pile lengths required for project.
Calculate total pile cost for project.
Perform additional iterations as desired.
30
F.S. = 2.00
Maximum
Optimum Required
Allowable "Ultimate"
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
31
F.S. = 2.00
Maximum
Optimum Required
Allowable "Ultimate"
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
• 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
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, tons
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
Optimum Allowable Pile Load, tons
Optimum Allowable Pile Load Histogram Condominiums
37
Condominiums - Proposed Designs
Allowable Number Estimated
Design Load, tons of Piles Footage
Original 70 205 15,580
Revised 72 180 14,040
SAVE: 25 1,540
$34,250 + cap costs
on $346,500 worth of piles
38
Condominiums - Proposed Designs
Allowable Number Estimated
Design Load, tons of Piles Footage
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
Optimum Allowable Pile Load, tons
Optimum Allowable Pile Load Histogram Condominiums
40
216-ton
column load
216-ton
column load
72 tons 72 tons 72 tons
100 tons 100 tons 100 tons
41
Condominiums - Proposed Designs
Allowable Number Estimated
Design Load, tons of Piles Footage
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
43
Questions / Comments?