National Wood Pole Standards - North American Wood Pole Council

National Wood Pole Standards - North American Wood Pole Council
National Wood Pole
Standards
Nelson G. Bingel III – NESC Chairman
.
President
(678) 850-1461
nbingel@nelsonresearch.net
1
Benefits of Wood as a Utility Pole Material
• Long-Life Span
• ~45 years national average without remedial treatment
• Lowest cost
• Both initial and full life-cycle costs
• Proven Performance
• “Go to” overhead line construction material since the
early 1900’s
• Climb-ability
• Ability to service attachments without heavy equipment
2
Benefits of Wood as a Utility Pole Material
• Supply Chain is Proven
• Even in natural disaster events where demand is high, the wood
pole industry has provided poles in required timeline.
• Beneficial Physical Properties
• Good insulator, resilience to wind and mechanical impacts
• Easy Maintenance and Modification in service
• “Green”
• a treated wood pole has a reduced environmental impact when
compared to other utility pole materials.
• A renewable and plentiful resource
“10 Features Often Overlooked About the Extraordinary Wood Pole.” North American Wood Pole Council. www.woodpoles.org
3
ANSI
American National Standards Institute
4
4
ANSI
American National Standards Institute
ANSI accredits the procedures of standards developing organizations
National consensus standards
Openness, balance, consensus and due process
5
5
ASC O5 Committee
American National Standards Institute
American Standards Committee O5
USERS
PRODUCERS
GENERAL INTEREST
6
6
National Wood Pole Standards
ASC O5
NESC
Accredited Standards
Committee O5:
Standards for Wood
Utility Structures
• Secretariat: AWPA
• Revised: 5 year cycle
• Founded in 1924
7
7
ASC O5 Standards
Poles
http://asco5.org/standards/
Glu-Lam
Crossarms
O5.4 - 2009 Naturally Durable Hardwood Poles
O5.5 - 2010 Wood Ground Wire Moulding
O5.6 - 2010 Solid Sawn Naturally Durable Hardwood Crossarms & Braces
O5.TR.01-2004 Photographic Manual of Wood Pole Characteristics
8
8
http://asco5.org/
9
9
http://asco5.org/standards/
10
10
Scope
Simple Cantilever
Transverse
Single Pole
Groundline
11
Maximum Stress Point
Solid, Round, Tapered, Cantilever
Load
(Wind Force on Wires, Equip., etc.)
Max Stress @ 1.5 Diameter Load Point
Distribution Usually Groundline
12
12
ANSI O5.1 – Wood Poles
Wood
Quality
Class
Loads
Fiber
Strength
Pole
Dimensions
13
13
Wood Quality
• Allowable knots
14
14
Wood Quality
• Sweep
15
15
Wood Quality
• Growth Rings
16
16
Pole Marking & Code Letters
17
17
Pole Marking & Code Letters
18
18
Transverse Wind Loads
Ice
19
19
Class Loads
2 ft
Lc
Class
10
9
7
6
5
4
3
2
1
H1
H2
H3
H4
H5
H6
Horizontal
Load (lb)
370
740
1,200
1,500
1,900
2,400
3,000
3,700
4,500
5,400
6,400
7,500
8,700
10,000
11,400
20
20
Class Loads
2 ft
Lc
Class
10
9
7
6
5
4
3
2
1
H1
H2
H3
H4
H5
H6
Horizontal
Load (lb)
370
740
Telco
1,200
1,500
1,900
2,400
Distribution
3,000
3,700
4,500
5,400
6,400
7,500 Transmission
8,700
10,000
11,400
21
21
Strengths are Average Values
22
22
Pole Populations
P
Steel Poles
Wood Poles
23
23
Applied Bending Load
2 ft
Lc
Applied Bending Load =
Lc x D (ft-lb)
D
Class 1
Class 2
Class 3
Class 4
Class 5
4,500 lb
3,700 lb
3,000 lb
2,400 lb
1,900 lb
24
24
L x D = Bending Moment (ft-lb)
50 ft Class 4
40 ft Class 4
2400 lb
2400 lb
41 ft
32 ft
76,800 ft-lb
98,400 ft-lb
25
25
Fiber Strength
Lc
Bending Capacity =
k
Tension
(psi)
x
Compression
(psi)
fiber strength
x
C3 (ft-lb)
Fiber Strength
26
26
Circumference3 Effect
MG/L = .000264 x Fiber Stress x Circumference 3
26”
37,120 ft-lb
34”
83,010 ft-lb
Circumference Increase - 30%
Bending Capacity Increase - 123%
27
27
Circumference3 Effect
MG/L = .000264 x Fiber Stress x Circumference 3
26”
34”
80-90%
Pole’s Bending Strength
In The Outer 2-3” Of Shell!
37,120 ft-lb
83,010 ft-lb
Circumference Increase - 30%
Bending Capacity Increase - 123%
28
28
Table 1 – Designated Fiber Strength
Group A
Air Seasoning
Group B
Boulton Drying
Group C
Steam Conditioning
Group D
Kiln Drying
29
29
Table 1 – Designated Fiber Strength
Southern Yellow Pine
8,000 psi
Douglas fir
8,000 psi
Western red cedar
6,000 psi
30
30
Pole Species
Distribution:
Douglas fir
Transmission
Douglas fir
Western red cedar
Distribution:
Southern Yellow Pine
Transmission:
Douglas fir
Western red cedar
Southern Pine
31
31
Table 1 – Designated Fiber Strength
1) The effects of conditioning on fiber strength have been accounted for in the Table 1
values provided that conditioning was performed within the limits herein prescribed.
4) The designated fiber strength represents a mean, groundline, fiber strength value
with a coefficient of variation equal to 0.20.
32
32
Through-boring
33
Oregon State University
-Through-Boring Project-
34
34
35
36
36
Through-boring
37
37
Table 1 – Designated Fiber Strength
1) The effects of conditioning on fiber strength have been accounted for in the Table 1
values provided that conditioning was performed within the limits herein prescribed.
4) The designated fiber strength represents a mean, groundline, fiber strength value
with a coefficient of variation equal to 0.20.
5) Where Douglas-fir (coastal or Interior North) are through-bored prior to treatment, to
account for the process, the designated fiber strength shall be reduced 5% to 7600 psi.
38
38
2017 Table 1 to add MOE
39
2017 Table 1 to add MOE
40
2017 Table 1 to add MOE
1) The fiber strength and MOE values in Table 1 apply to wood utility poles meeting this
standard. The effects of conditioning on fiber strength and MOE have been accounted for
………….
7) The Modulus of Elasticity (MOE) represents a mean value.
41
Circumference Dimensions
6ft
TIP
G/L
Bending Capacity =
k
x
fiber strength
x
C3 (ft-lb)
42
42
Circumference Dimension Tables
1) The figures in this column are not recommended embedment depths; rather,
these values are intended for use only when a definition of groundline is necessary
in order to apply requirements relating to scars, straightness, etc.
43
43
Annex B: Groundline Stresses
44
44
Annex B: Groundline Stresses
Minimum circumferences specified at 6 feet from the butt
Were calculated so each species in a given class
Can support the class horizontal load applied 2 ft from the tip
Applied Bending Load =
Lc x D (ft-lb)
k
x
Bending Capacity =
fiber strength x C3 (ft-lb)
45
45
Pole Dimension Table
Southern Pine and Douglas Fir
(in)
46
Pole Dimension Table
Applied Bending Load=
Southern Pine and
Douglas
Fir
Class
Load x Distance
2,400 lbs x 32 ft =
76,800 ft-lbs
(in)
47
Pole Dimension Table
Applied Bending Load=
Southern Pine and
Douglas
Fir
Class
Load x Distance
2,400 lbs x 32 ft =
76,800 ft-lbs
(in)
Bending Capacity =
k x fiber strength x C3
.000264 x 8000 x 33.53 =
79,401 ft-lbs
48
40 ft Class 4 Poles
2400 lb
Douglas fir
(8000 psi)
33 1/2”
Western Red Cedar
(6000 psi)
36 1/2”
49
49
Annex B: Groundline Stresses
Note 7
Average circumference tapers
in the groundline zone of a pole
50
50
ANSI O5.1 Summary
2 ft
Lc
All Species
Same Length & Class
Similar Load Capacity
Bending
Capacity
= k
x
fiber strength
x
C3 (ft-lb)
51
51
Fiber Strength Values
Forest Products Lab
1965 Publication
Fiber Strength
Derivation
52
52
FPL 39 Table 4
Final Adopted Fiber Strengths
53
53
FPL 39 Table 4
Final Adopted Fiber Strengths
Near 5% Lower Exclusion Limit
Of Actual Average Bending Strength
Of Three Pole Groups
For Grade B Construction
54
54
Annex C Data < 50 ft
55
55
Annex C Data – 50 ft +
56
56
Full Scale Break Tests
Douglas Fir Poles
16000
MORGL (psi)
14000
ASTM
12000
10000
8000
EPRI
6000
4000
Mean = 8380 psi
L5 = 6401 psi
2000
0
15
25
35
45
Mean = 6630 psi
L5 = 4825 psi
55
65
75
85
Groundline Circumference (GC) (in)
57
57
Full Scale Break Tests
Douglas Fir Poles
16000
MORGL (psi)
14000
ASTM
12000
to
EPRI
Previous Fiber Strengths
10000
8000
6000
4000
Mean = 8380 psi
L5 = 6401 psi
2000
0
No Change
15
25
35
45
Mean = 6630 psi
L5 = 4825 psi
55
65
75
85
Groundline Circumference (GC) (in)
58
58
Annex A
Fiber Stress Height Effect
59
59
Annex A
Fiber Stress Height Effect
Round timbers are known to
decrease in ultimate unit strength
with height above ground.
60
60
Actual Pole Dimensions
?
??
?
?? WA
?
?
?
?
OR
?
?
?
?
?
MT
ME
ND
?
MN
ID
?
SD
VT NH
MI
WI
?
WY
?
PA
IA
NE
NV
OH
UT
AZ
VA
MO
KY
TN
OK
AR
NM
?
?
MS
TX
?
LA
NJ
WV
CO
KS
MA
RI
CT
MCD DE
D
IN
IL
CA
NY
AL
??
NC
??
?
SC
??
??
GA
??
?
?
Sample Locations
?
? Coastal DF & Western Red (3)
? Northern Red Pine (3)
? Southern Yellow Pine (16)
? Western Red Cedar (5)
Coastal Douglas Fir (8)
FL
61
61
Pole Circumference Data
• Coastal Douglas fir
6,997 poles
9 Producers; 11 Locations
• Southern Yellow Pine
6,634 poles
11 Producers; 16 Locations
• Western Red Cedar
6,982 poles
5 Producers; 9 Locations
• Northern Red Pine
2,266 poles
2 Producers; 4 Locations
Grand Total 22,859 poles
62
62
Fiber Stress Height Effect (FSHE)
• Tips average 1.5 to 2 classes larger
• Poles 55 ft and shorter
• Maximum stress is usually at G/L
– FSHE not applied
• Maximum stress for guyed poles may be above G/L
– Oversize offsets fiber stress height effect
• Poles 60 ft and taller
• If maximum stress is at the G/L, no FSHE
• If maximum stress is above ground, tables for
reduction
63
63
ASC O5 Standards
Poles
http://asco5.org/standards/
Glu-Lam
Crossarms
O5.4 - 2009 Naturally Durable Hardwood Poles
O5.5 - 2010 Wood Ground Wire Moulding
O5.6 - 2010 Solid Sawn Naturally Durable Hardwood Crossarms & Braces
O5.TR.01-2004 Photographic Manual of Wood Pole Characteristics
64
64
National Wood Pole Standards
ASC O5
NESC
Accredited Standards
Committee O5:
Standards for Wood
Utility Structures
• Secretariat: AWPA
• Revised: 5 year cycle
• Founded in 1924
65
65
National Overhead Line Standard
NESC
ANSI C2:
National Electrical
Safety Code
• Secretariat: IEEE
(Institute of Electrical and
Electronics Engineers)
• Revised: 5 year cycle
• Established in 1915
66
NESC Committee Structure
Main
Committee
Chairman
Executive
Subcommittee
Chairman
Technical
Subcommittees
Vice Chair
Secretary-IEEE
25 – 35 Members
Secretary
6 - 10 Members
Chairman
Secretary
SC 1 – Coordination; Sections 1,2,3
SC 2 – Grounding
SC 3 – Substations
SC 4 – Overhead Lines – Clearances
SC 5 – Overhead Lines – Strength & Loading
SC 7 – Underground Lines
SC 8 – Work Rules
6767
Purpose of the NESC
68
Purpose of the NESC
B. NESC rules contain the basic provisions, under
specified conditions, that are considered necessary for
the safeguarding of:
1. The Public
2. Utility workers (employees and contractors), and
3. Utility facilities
C. This code is not intended as a design specification or as
an instruction manual.
69
NESC Committee Structure
Main
Committee
Chairman
Executive
Subcommittee
Chairman
Technical
Subcommittees
Vice Chair
Secretary-IEEE
25 – 35 Members
Secretary
6 - 10 Members
Chairman
Secretary
SC 1 – Coordination; Sections 1,2,3
SC 2 – Grounding
SC 3 – Substations
SC 4 – Overhead Lines – Clearances
SC 5 – Overhead Lines – Strength & Loading
SC 7 – Underground Lines
SC 8 – Work Rules
7070
Overhead Lines Subcommittee 5
Section 24
Grades of Construction
• Grades B, C & N
(B is the highest)
Section 25
Loading for Grade B&C
• Load Factors
Section 26
Strength requirements
• Strength Factors
• Rule 250B:
Combined ice and Wind
District loading
• Rule 250C:
Extreme wind Loading
• Rule 250D:
Extreme Ice with concurrent
wind loading
71
Overhead Lines Subcommittee 5
Section 24
Grades of Construction
• Grades B, C & N
(B is the highest)
Section 25
Loading for Grade B&C
• Load Factors
• Rule 250B:
Combined ice and Wind
District loading
• Rule 250C:
Extreme wind Loading
• Rule 250D:
Extreme Ice with concurrent
wind loading
Section 26
Strength requirements
• Strength Factors
Section 27
Insulators
• Electrical Strength
• Mechanical Strength
72
Section 24: Grades of Construction
• Grade B: (3.85 SF)
• Crossing Limited Access Highways
• Crossing Railways
• Crossing Navigable Waterways
• Grade C: (2.06 SF)
• All other standard construction
• Grade N: (Strength shall exceed expected loads)
• Mainly used for temporary and emergency construction
73
73
Section 25 – Loadings for Grade B & C
TRANSVERSE
V
E
R
T
I
C
A
L
74
74
Transverse Loading Usually Governs
Wire with Ice
75
Calculating Transverse Loads
Wind Bending Loads On:
Wires
Ice
Pole
Equipment
Offset Bending Loads
Wire Tension
76
76
Section 25: Loading for Grade B & C
• Rule 250B: District Loading
Combined Ice and Wind
• Rule 250C: Extreme Wind Loading
(60ft Exemption)
• Rule 250D: Extreme Ice
With Concurrent Wind Loading
(60ft Exemption)
77
77
NESC District Loading
Winter Storm
½” Ice – 40 mph
¼” Ice – 40 mph
40 mph = 4 lbs/sqft
60 mph = 9 lbs/sqft
0” Ice – 60 mph
78
78
Medium Loading District
40 mph
¼” Ice
79
Wind Load Increase per Wire Sizes
0.75”
2x
1.50”
+100%
2x
3.00”
+200%
Double wire diameter = Double the load
80 80
Wind Load Increase With 0.25” Radial Ice
0.75”
1.50”
3.00”
2.00”
+33%
3.50”
+17%
.25” Ice
1.25”
+67%
8181
District Loads vs Wire Size
9
8
7
RELATIVE LOAD
6
NESC-L
5
No ICE
4
NESC-M
3
1/4” ICE
2
1/2” ICE
NESC-H
1
0
4ACSR
1/0
336
556
CONDUCTOR (SMALLEST TO LARGEST)
82
82
Section 25: Loading for Grade B & C
• Rule 250B: District Loading
Deterministic
Combined Ice and Wind
83
83
Extreme Wind– Rule 250C
(60 ft. Exclusion)
Summer Storm
85 mph = 18.5 lbs/sqft
90 mph = 21 lbs/sqft
130 mph = 43 lbs/sqft
150 mph = 58 lbs/sqft
84
84
Extreme Ice with Concurrent Wind –Rule 250D
(60 ft. Exclusion)
Winter Storm
Radial
Ice
0”
0.25”
0.5”
Wind Speeds
0.75”
30 mph
1.0”
40 mph
50 mph
60 mph
85
85
Section 25: Loading for Grade B & C
• Rule 250B: District Loading
Deterministic
Combined Ice and Wind
• Rule 250C: Extreme Wind Loading Probabilistic
(60ft Exemption)
• Rule 250D: Extreme Ice Probabilistic
With Concurrent Wind Loading
(60ft Exemption)
86
86
Section 25 Load Cases
• Rule 250 B - Combined Ice & Wind
–
–
–
–
Light
0” Ice
Medium
¼” Ice
Heavy
½” Ice
Loads to be Factored
60 mph
40 mph
40 mph
• Rule 250 C – Extreme Wind
– Poles Taller than 60 feet Above Ground
– Wind only (no ice)
– Ultimate Load with probability of occurrence
• Rule 250 D – Extreme Ice with Wind
– Poles Taller than 60 feet Above Ground
– Ice Thickness with Concurrent Wind
– Ultimate Load with probability of occurrence
87
Load
Strength
Strength
Pole Strength x SF
Pole Strength x SF
>
>
Load
Storm Load
x
LF (B)
Storm Load
x
LF (C)
Storm Load
x
4 (B)
Storm Load
x
2 (C)
Alternate Method
Pole Strength
Pole Strength
>
>
88
Grade Cx
Grade C
Vertical Loads
1.50
1.90
1.90
Transverse Loads
(wind)
2.50
2.20
1.75
Longitudinal
Loads
1.10
No Req.
No Req.
250C
Wind Loads
1.00
1.00
1.00
Ice and Wind
loads
1.00
1.00
1.00
Rule 250B
Grade B
250D
Section 25: Table 253.1-Load Factors
89
Section 26: Strength Factors
250C & 250D
Rule 250B
Table 261-1
Metal Structures
Grade B
Grade C
1.0
1.0
Wood Structures
0.65
0.85
Metal Structures
1.00
1.00
Wood Structures
0.75
0.75
Fiber Strength (ANSI)
× Strength Factor (NESC)=
Allowable Stress of Pole
90
90
Load
Strength
Strength
Pole Strength x SF
Pole Strength x SF
>
>
Load
Storm Load
x
LF (B)
Storm Load
x
LF (C)
Storm Load
x
4 (B)
Storm Load
x
2 (C)
Alternate Method
Pole Strength
Pole Strength
>
>
91
Load
Strength
Strength
Pole Strength x .65
Pole Strength x .85
>
>
Load
Storm Load
x
2.5 (B)
Storm Load
x
1.75 (C)
Alternate Method
Pole Strength
Pole Strength
>
>
3.85 x 4 (B)
Storm Load
2.06 x 2 (C)
Storm Load
92
Section 24: Grades of Construction
• Grade B: (3.85 SF)
• Crossing Limited Access Highways
• Crossing Railways
• Crossing Navigable Waterways
• Grade C: (2.06 SF)
• All other standard construction
• Grade N: (Strength shall exceed expected loads)
• Mainly used for temporary and emergency construction
93
93
94
900 lb
Equate the
Total Storm Load
to a
Single Horizontal Load
applied
2 feet from the tip.
95
Load
<
Strength
ANSI O5.1
NESC
Grade B
900 lb Storm Load
x 3.85 (Grade B)
= 3465
lb
Class 1
Class 2
Class 3
Class 4
Class 5
4500 lb
3700 lb
3000 lb
2400 lb
1900 lb
96
Load
<
Strength
ANSI O5.1
NESC
Grade C
900 lb Storm Load
x 2.06 (Grade C)
= 1854
lb
Class 1
Class 2
Class 3
Class 4
Class 5
4500 lb
3700 lb
3000 lb
2400 lb
1900 lb
97
IEEE Online Courses – MOOC’s
MOOC #1
NESC Overview
MOOC #2
2017 Changes
http://standards.ieee.org/about/nesc/
98
Technical Subcommittees
SC1 - Coordination between technical subcommittees
Sections 1, 2 and 3
 SC2 - Grounding Methods - Section 9
 SC3 - Electric Supply Stations - Sections 10-19
 SC4 - Overhead Lines - Clearances - Section 20-23
 SC5 - Overhead Lines - Strength and Loading

Sections 24-27
 SC7 - Underground Lines - Sections 30-39
 SC8 - Work Rules - Sections 40-43
99
Online Courses – MOOC’s
MOOC #1
NESC Overview
MOOC #2
2017 Changes
MOOC #3
Grounding Methods
MOOC #4
Electric Supply Stations
MOOC #5
Overhead Lines – Clearances and S&L
MOOC #6
Underground Lines
MOOC #7
Work Rules
10
100
NESC Mobile App
Released !!!!
•
•
Mobile device or tablet
iOS, Android, Windows
•
Full printed document
•
Enhanced features
– Instant access to formulas, equations
and calculations with context
– Quick look-up of terms
– Quick access to sections
http://standards.ieee.org/about/nesc/mobile_app.html
101
NESC Mobile App
Home Page
Table of Contents
Tables & Equations
102
NESC Mobile App
Search the NESC
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103
National Wood Pole
Standards
Nelson G. Bingel III – NESC Chairman
.
President
(678) 850-1461
nbingel@nelsonresearch.net
104
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