TIA SWT Support Structure Design Supplement Draft 03292011 R0

ANSI/TIA-222-G-DS1-2011
DRAFT 3-29-2011 Rev 0
ANSI/TIA STANDARD
DESIGN SUPPLEMENT
Design Supplement for Small Wind Turbine
Support Structures
TIA-222-G-DS1 Draft 3-29-2011 Rev 0
TELECOMMUNICATIONS
INDUSTRY ASSOCIATION
TR14.7 Sub-committee
tiaonline.org

ANSI/TIA-222-G-DS1-2011
DRAFT 3-29-2011 Rev 0
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ANSI/TIA-222-G-DS1-2011
DRAFT 3-29-2011 Rev 0
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ANSI/TIA-222-G-DS1-2011
DRAFT 3-29-2011 Rev 0
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SMALL WIND TURBINE SUPPORT STRUCTURES
TABLE OF CONTENTS
ANSI/TIA-222-G-DS1-2011
DRAFT 3-29-2011 Rev 0
OBJECTIVE 2
SCOPE 2
1.0 GENERAL 2
2.0 TURBINE MANUFACTURER DATA 4
3.0 EFFECTIVE PROJECTED AREA 4
4.0 DRAG FACTORS FOR POLE STRUCTURES 5
5.0 EXTREME WIND CONDITION 5
6.0 EXTREME ICE CONDITION 5
7.0 EXTREME EARTHQUAKE CONDITION 5
8.0 CRITICAL TURBINE MOMENTS 6
9.0 SERVICEABILITY REQUIREMENT 6
10.0 DYNAMIC REQUIREMENTS 6
11.0 FATIGUE STRENGTH 7
12.0 OTHER STRUCTURAL MATERIAL 12
13.0 FOUNDATIONS 12
14.0 MAINTENANCE AND MATERIAL ASSESSMENT 13
REFERENCE TABLES 14
ANNEX A: REFERENCES (INFORMATIVE) 17
Note: Informative annexes contain additional information that are not considered
part of the standard.
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Small Wind Turbine Support Structures
OBJECTIVE
The objective of this Design Supplement is to provide recognized literature intended to
be used in conjunction with the ANSI/TIA-222-G Standard, “Structural Standard for
Antenna Supporting Structures and Antennas” (TIA) for the design and analysis of
structures supporting Small Wind Turbines (SWT’s) defined as wind turbines with rotor
swept areas less than 2,200 sq. ft. [200 sq. m].
This Design Supplement defines how specific portions of the TIA Standard shall be
applied to SWT supporting structures and provides supplementary requirements that
pertain specifically to the unique characteristics of SWT supporting structures.
The provisions of this Design Supplement are intended to be used for the development
of standard designs for SWT supporting structures and for the design and analysis of
site-specific structures.
SCOPE
This Design Supplement is intended to apply to self-supporting or bracketed latticed
towers, guyed masts and pole structures that support single or multiple SWTs that may
also support antennas and other appurtenances.
The design and analysis of turbine components are not included within the scope of this
Design Supplement.
1.0 GENERAL
1.1 Design Criteria
SWT supporting structures shall be in conformance with the requirements of TIA and
the additional supplementary requirements of this Design Supplement.
The design parameters used for standard designs for SWT supporting structures
developed in accordance with this Design Supplement shall be verified prior to
installation.
Conformance to this Design Supplement is not required for structures supporting wind
turbines with rotor swept areas less than 22 sq. ft. [2 sq. m]. Structures supporting
turbines with rotor swept areas less than 22 sq. ft. [2 sq. m] may be designed and/or
analyzed in accordance with the TIA Standard with each turbine considered as an
appurtenance. The effective projected area of each turbine shall be determined in
accordance with TIA Section 3.0. The effective projected area shall be considered to be
constant for all wind directions. The wind force based on the effective projected area of
each turbine shall be considered as a wind load using a load factor equal to 1.6 and a
wake interference factor, Ka, equal to 1.0.
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1.2 Turbine Model
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For all loading conditions with the exception of fatigue, a turbine shall be modeled as a
mass and an effective projected area.
Unless otherwise specified, the center of mass and the centroid of the effective
projected area shall be considered to be at the hub height of the turbine and assumed
to be distributed symmetrically about the vertical centerline of the turbine base.
When a horizontal offset of the center of mass from the vertical centerline of the turbine
base is specified by the turbine manufacturer, the additional overturning moment on the
supporting structure due to turbine weight shall be considered to occur in the direction
which adds to the overturning moment from the horizontal turbine thrust.
For fatigue loading, unless otherwise specified, the turbine effective projected area shall
be replaced with the equivalent constant range fatigue loads determined in accordance
with Section 11.0.
For the purpose of determining factored extreme loading conditions, turbine weight shall
be considered a dead load and turbine forces and moments shall be considered as wind
loads.
1.3 Definitions
Equivalent constant range load: a constant amplitude load range intended to
represent the fatigue effects of actual variable amplitude loading events.
Flange plate: a base, top or intermediate flange welded to a latticed tower leg or pole
structure.
Hub height above turbine base: the height of the center of the wind turbine rotor
above the turbine base.
Initial tension condition: the equilibrium position of a guyed mast (with corresponding
forces in the components of the mast) with guys at their specified installation tension.
Turbine base: the base of the turbine that interfaces with the supporting structure.
1.4 Abbreviations
AISC American Institute of Steel Construction Manual, 13 th Edition
AWEA American Wind Energy Association Standard AWEA 9.1-2009
AWS American Welding Society Standard AWS D1.1/D1.1M:2010
SWT Small Wind Turbine
TIA Telecommunications Industry Association Standard ANSI/TIA-222-G
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2.0 TURBINE MANUFACTURER DATA
The following turbine data shall be provided by the turbine manufacturer:
1. Type of turbine: horizontal or vertical axis machine
2. Rotor diameter, ft [m]
3. Rotational Rotor Speed at electrical power rating of turbine, RPM
4. Hub height above turbine base, ft [m]
5. Maximum turbine horizontal thrust (unfactored), Lb [N]
6. Wind speed at hub height associated with the specified maximum turbine horizontal
thrust, mph [m/s]
7. Weight of turbine, Lb [N]
8. Horizontal offset of turbine weight from vertical centerline of turbine base, ft [m]
9. Weight of rotor (blades and hub), Lb [N]
10. Distance from center of rotor mass to vertical centerline of turbine base, ft [m]
11. Clearance requirements of turbine blades to the supporting structure (considering
deflected shape of blades under wind loading)
12. Connection details for the turbine base
13. Natural frequency limitations of the supporting structure, Hertz
3.0 EFFECTIVE PROJECTED AREA
The effective projected area of a turbine shall be calculated in accordance with this
Section unless the effective projected area of the turbine is specified by the turbine
manufacturer. The effective projected area of a turbine shall be considered to be
constant for all wind directions with a wake interference factor, K a , equal to 1.0.
Unless otherwise specified by the turbine manufacturer, the effective projected area of
the turbine, (EPA) T , shall be calculated in accordance with the following equation n:
(EPA) T = Fmaxt (ft) 2
0.00256(Vmax) 2
(EPA) T = Fmaxt (m) 2
0.613(Vmax) 2
where:
Fmaxt = maximum unfactored horizontal turbine thrust, lbs [N]
Vht = wind speed at hub height associated with the specified maximum turbine
horizontal thrust, mph [m/s]
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4.0 DRAG FACTORS FOR POLE STRUCUTRES
The TIA drag factors for pole structures consider a minimum level of roughness due to
attachments common to communication structures. For SWT supporting pole structures
without appurtenances attached along their height, the drag factors specified in Table
2.0 may be used in place of the TIA drag factors.
5.0 EXTREME WIND CONDITION
The TIA basic wind speed (50-year return, 3-second gust at 10 m height) used for
investigating the TIA extreme wind condition shall be the larger of the basic wind speed
specified by the turbine manufacture, the basic wind speed for the site and 110 mph [50
m/s].
Note: The fatigue investigation criteria specified in Section 11.0 is based on the
supporting structure satisfying a minimum strength requirements equivalent to a 110
mph [50 m/s] design basic wind speed, exposure category C. Lower strength
requirements would require extensive fatigue investigations of the supporting structure
that are not within the scope of this Design Supplement.
6.0 EXTREME ICE CONDITION
The design ice thickness and corresponding basic wind speed shall be determined from
the TIA Standard when a specific site location is specified. The default design ice
thickness for standard designs shall be 1 inch [25 mm] occurring simultaneously with a
40 mph [18 m/s] basic wind speed. Unless more accurate data is provided for the
turbine, the weight of the turbine shall be increased 25% and the calculated (EPA) T of
the turbine shall be increased 15% from the no-ice condition.
7.0 EXTREME EARTHQUAKE CONDITION
The operational loads of the turbine shall be considered insignificant compared to
earthquake loading due to the mass of the turbine and the supporting structure.
Operational loading need not be considered to occur simultaneously with earthquake
loading. The masses of the turbine, the structure and all appurtenances shall be
included in the determination of earthquake loading. The default spectral response at
short periods (Ss) shall be considered as 0.60. Earthquake analysis in accordance with
TIA shall be required for SWT supporting structures located in areas with Ss values
greater than 0.60.
Note: SWT supporting structures have a lower Ss threshold value compared to antenna
supporting structures.
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8.0 CRITICAL TURBINE MOMENTS
Unless otherwise specified by the turbine manufacturer, the extreme wind condition
shall be assumed to govern over other turbine operational loading conditions that
subject the supporting structure to an overturning or twisting moment. These conditions
include braking, shorts, shut down, maximum rotational speed condition, extreme
yawing, etc.
When a critical turbine moment is specified by the turbine manufacturer, the moment
shall be investigated by considering an additional extreme wind loading condition
without ice. Unless otherwise specified, the specified moment shall be considered to
occur simultaneously with a 25 mph [11 m/s] basic wind speed with the calculated
effective projected area of the turbine (EPA) T and the TIA importance factor, I, for wind
load without ice, based on the structure classification. Unless otherwise specified, a
load factor of 1.6 shall be applied to the specified moment. A specified overturning
moment shall be considered to occur at the top of the structure in the same direction as
the wind. A specified twisting (yaw) moment shall be considered to act about the
vertical centerline of the turbine base in a counterclockwise direction in the plan view.
9.0 SERVICEABILITY REQUIREMENT
Unless otherwise specified, the stiffness of the supporting structure shall result in a tip
deflection no greater than 1% of the structure height for the TIA service loading
condition (60 mph [27 m/s] basic wind speed without ice) with the calculated effective
projected area of the turbine (EPA) T .
10.0 DYNAMIC REQUIREMENTS
The natural frequency modes involving single, double and triple curvature of the
supporting structure shall be determined for a no-ice condition when natural frequencies
of the support structure to be avoided are specified by the turbine manufacturer. One of
the elastic three-dimensional models specified in TIA shall be used to determine the
fundamental frequency modes. The simplified TIA fundamental frequency equations
shall not be used for SWT supporting structures. The masses of the turbine, the
structure and all appurtenances shall be included in the structural model at the proper
locations.
Unless a detailed analysis is undertaken to determine an appropriate foundation spring
constant to be used in the determination of natural frequencies, the calculated natural
frequencies of the structure shall be adjusted +/- 10% for comparison to the turbine
manufacturer’s specified natural frequencies. When frequency ranges or min/max
frequencies are provided by the turbine manufacturer, no adjustments to the calculated
natural frequencies of the supporting structure are required.
Note: Natural frequency modes involving torsion may require investigation for vertical
axis turbines when specified by the turbine manufacturer.
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11.0 FATIGUE STRENGTH
11.1 Equivalent Constant Range Wind Loading on Supporting Structure
Unless otherwise specified, fatigue wind loading on the supporting structure and
supported appurtenances (excluding the turbine) shall be considered as an additional
service loading combination (K fd = 0.85 for all structures) using a 30 mph [13 m/s]
uniform wind speed (K z , K zt and G h equal to 1.0) and the importance factor for fatigue
loading specified in Table 11-1 based on the TIA structure classification for the
supporting structure. The fatigue loading on the supporting structure shall be
considered to occur simultaneously with the equivalent constant range turbine loads
specified in Section 11.2.
11.2 Equivalent Constant Range Turbine Loads
Equivalent constant range fatigue loads for horizontal axis turbines shall be calculated
from the following equations:
Fxt = equivalent constant range turbine horizontal force, lbs [N]
= (K fd )(I f )(C fxt )(Dr) 2
Mty = equivalent constant range turbine overturning moment, ft-lbs [N-m]
= (K fd )[2(Wtr)(Lrc) + (Dr)(Fxt) / 12]
Mtx = equivalent constant range turbine shaft torsion, ft-lbs, [N-m]
= (K fd )[(I f )(C mtx )(Dr) 2 / Nr + 0.005(Wtr)(Dr)]
where:
K fd = 0.85
I f = importance factor for fatigue from Table 11-1
C fxt = 1.0 [48]
Dr = rotor diameter, ft [m]
Wtr
Lrc
= weight of rotor (hub and blades), lbs [N]
= distance between center of gravity of rotor and centerline of the supporting
structure, ft [m]
C mtx = 275 [4000]
Nr = rotor rotational speed, rpm
Note: K fd accounts for the probability of the applied load range occurring form a
direction that creates a response in any one given support structure component.
The horizontal force, Fxt, shall be applied concentrically in the direction of the wind at
the hub height of the turbine. The overturning moment, Mty, shall be applied at the top
of the supporting structure in a vertical plane in the direction which adds to the
overturning moment resulting from Fxt. The moment, Mtx, shall be applied at the top of
the supporting structure in a vertical plane normal to the wind direction (shaft torsion).
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ANSI/TIA-222-G-DS1-2011
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The unit direction vector for Mtx shall be in the direction of the wind. Alternately, the
moments Mty and Mtx may be combined into a resultant overturning moment and
applied in the direction which adds to the overturning moment resulting from Fxt.
Note: Turbine weight shall be included in the fatigue investigation analysis. The
equivalent constant range fatigue load Fxt includes wind loading on the turbine;
therefore, the effective projected area of the turbine is not included in the fatigue
investigation analysis.
Equivalent constant range fatigue loads for vertical axis turbines shall be provided by
the turbine manufacturer. The equivalent constant range fatigue loads shall be based
on the turbine cycling between 50% and 150% of the rated power at a 30 mph wind
speed. Fatigue loads shall include the effects of eccentric wind loading on the turbine
and the effects of eccentric rotor mass.
11.3 Fatigue Analysis
An analysis of the supporting structure shall be performed using the equivalent constant
range loads from Sections 11.1 and 11.2. The resulting member stresses shall be
considered as equivalent fatigue damage stress ranges. Equivalent fatigue damage
stress ranges shall not exceed the design stress ranges specified in Section 11.4 for the
indentified components. Other components of SWT supporting structures shall be
considered to have adequate fatigue strength when properly sized for the extreme wind
loading condition specified in Section 5.0.
Note: The design stress ranges specified in Section 11.4 are considered as threshold
fatigue stress ranges (indefinite number of cycles); therefore, the number of cycles
based on the design life of the structure is not required for a fatigue analysis performed
in accordance with this Design Supplement.
11.3.1 Self-Supporting or Bracketed Structures
Analysis of pole and latticed self-supporting or bracketed structures shall be performed
using a load factor of zero for dead load and a load factor of 1.0 for all other loads. The
stress range in each component shall be considered to equal the absolute value of the
stress in the component.
11.3.2 Cantilever Portions of Guyed Masts
The cantilever portion of a guyed mast shall be modeled as a self-supporting structure
in accordance with Section 11.3.1.
11.3.3 Guyed Masts below the Cantilever
11.3.3.1 Latticed Masts
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The full height of the mast with the cantilever shall be analyzed using a load factor equal
to 1.0 for all loads. The results of the initial tension condition and the results of the
fatigue analysis shall be used to determine the stress ranges in the mast.
Leg members below the cantilever that are subjected solely to axial compression from
the fatigue analysis need not be investigated for fatigue.
The stress range in leg members below the cantilever subjected to axial tension from
the fatigue analysis shall be considered equal to the sum of the leg tension stress from
the fatigue loading condition and the absolute value of the leg stress from the initial
tension condition.
The stress range in bracing members shall be equal to the absolute value of the stress
form the fatigue analysis.
11.3.3.2 Tubular Pole Masts
The full height of the mast with the cantilever shall be analyzed using a load factor equal
to 1.0 for all loads. The results of the initial tension condition and the results of the
fatigue analysis shall be used to determine the stress ranges in the mast.
Tubular mast components below the cantilever with cross sections that are subjected
solely to compression stresses (due to combined axial load and bending) from the
fatigue analysis need not be investigated for fatigue.
The stress ranges in a tubular mast component below the cantilever subjected to
tension stresses from the fatigue analysis shall be considered equal to the sum of the
maximum tensile stress in the component from the fatigue analysis and the absolute
value of the maximum stress in the component from the initial tension condition.
11.4 Design Stress Ranges
The stresses calculated form the fatigue analysis shall be considered as equivalent
fatigue damage stress ranges and shall not exceed the values specified in Sections
11.4.1 and 11.4.2 unless otherwise specified.
11.4.1 Category A Components (limited to a stress range of 4.5 ksi [31 MPa]):
1. Pole structures at ports or welded attachments.
2. Pole flanges connected with a full penetration weld without a backer
3. Pole flanges connected with a full penetration weld with a backer connected to the
flange with a full penetration or continuous fillet weld.
4. Pole flanges or latticed tower legs, with stiffeners connected to a continuous top
annular ring plate.
5. Legs in latticed structures with welded connection plates, flanges or other welded
attachments.
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11.4.2 Category B Components (limited to a stress range of 2.6 ksi [18 MPa]):
1. Pole flanges connected with a full penetration weld with a backer connected to the
flange without a full penetration or continuous fillet weld.
2. Pole socketed flanges connected with double fillet welds.
3. Latticed structure legs and pole flanges with stiffeners.
4. Main load carrying bracing members in latticed structures with effective
slenderness ratios less than 60 that have welded end connections or welded
gusset plates for use with a bolted connection.
5. Tension only bracing members with welded end connections or welded gusset
plates
11.4.3 Anchor Rods (limited to a combined stress range of 7.0 ksi [48 MPa]
The stress range shall be calculated by combining stresses due to axial loads and
bending on the individual anchor rods regardless of whether grout is utilized and
regardless of the distance between the bottom of the leveling nut and top of concrete.
Axial anchor rod forces from a moment reaction shall be determined from an elastic
distribution of anchor rod forces. The distance between the top of concrete and the
bottom of the leveling nut shall be used to determine anchor rod bending moments
based on assuming an inflection point equal to 0.65 times the gap dimension. Anchor
rod bending stresses shall be determined using the anchor rod elastic section modulus.
For anchor rods arranged in a round pattern, the following equations apply (other
arrangements shall follow an equivalent methodology):
dn
= d - 0.9743 / n t inches
= d - 0.9382(p) mm
S = [π(dn) 3 ] / 32
Fa1 = anchor rod axial load due to an applied vertical reaction
= Pa / n ar
Fa2 = anchor rod axial load due to an applied resultant overturning moment reaction
= 4(Ma) / [n ar (Dp)]
Va1 = anchor rod shear load due to an applied resultant shear reaction
= 2(Va) / n ar
Va2 = anchor rod shear force due to an applied torsional moment reaction
= 2(Ta) / [n ar (Dp)]
Mb = anchor rod bending due to an applied shear reaction
= (Va1 + Va2)(0.65)(Iar)
Ffar = stress range in anchor rod
= (Fa1 + Fa2) / (An) + Mb / S
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where:
dn = tensile root diameter of anchor rod
d = nominal diameter of anchor rod
n t = number of threads per inch
p = pitch of threads, mm
S = section modulus of anchor rod
Pa = applied vertical reaction (larger of tension or compression reaction) on anchor
rod group
n ar = number of anchor rods
Ma = applied resultant overturning moment reaction on anchor rod group
Dp = anchor rod bolt circle
Va = applied resultant shear reaction on anchor rod group
Ta = applied torsional moment reaction on anchor rod group
Iar = length form top of concrete to bottom of leveling nut
An = net area of anchor rod through the treaded portion
11.5 Miscellaneous Requirements for Fatigue Strength
11.5.1 Latticed Structures
The maximum effective slenderness ratios for members and the minimum gusset plate
thicknesses for member connections shall be determined form Table 11-2 unless
otherwise specified.
11.5.2 Guy Anchorages
Guy connection plates for guyed mast anchor rods shall be limited to designs using
pinned connection plates.
11.5.3 Connection Bolts for Turbine Bases
Bolted connections shall be fully tensioned in accordance with the AISC Standard. The
number, size, arrangement and grade of turbine base connection bolts shall be
specified by the turbine manufacturer.
11.5.4 Complete Penetration Flange Plate Welds for Pole Structures
A reinforcing outer fillet weld shall be provided for all complete penetration welds. The
size of the weld reinforcement shall be no smaller than 25% of the pole wall but need
not be greater than 0.375 inches [10 mm].
Complete penetration welds made without backers shall have an inner fillet weld size
equal to the size of the reinforcing outer fillet weld.
Backer bars, when used in complete penetration welds, shall be continuous for their full
length with all backer bar joints made with complete penetration groove weld butt joints
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in accordance with AWS. Backer bars shall not exceed 0.375 inches [10 mm] when a
fillet weld is used to attach the backer bar to the flange plate.
11.5.5 Socketed Flange Plate Welds for Pole Structures
The inner fillet weld shall be an equal leg fillet weld with the weld size not less than the
pole wall thickness minus 1/16 inch [2 mm]. The outer fillet weld shall be an unequal
leg fillet weld with the long leg of the fillet weld along the pole wall with an approximately
30 degree angle between the fillet weld and the pole wall.
12.0 OTHER STRUCTURAL MATERIALS
This Design Supplement has been developed primarily for steel SWT supporting
structures but may also be applied to other materials using appropriate resistance
factors to result in an equivalent level of reliability.
12.1 Extreme Loading Conditions
The nominal strengths for extreme loading conditions for material other than steel shall
be based on the minimum strengths guaranteed by the manufacturer of the material or
alternately, based on tests to determine strengths of 95% survival probability with a 95%
confidence limit. Resistance factors applied to nominal strengths shall be in accordance
with Table 12-1.
12.2 Fatigue Loading Condition
The design stress range values indicted in Section 11.4 include appropriate resistance
factors applied to the nominal stress ranges for steel components manufactured in
accordance with TIA. Appropriate resistance factors for other materials shall be applied
to the nominal fatigue stress ranges in accordance with the Table 12-2.
For materials that do not display a fatigue threshold limit, the number of cycles used to
determine the nominal stress range for use with this Design Supplement shall be based
on 5 million cycles.
13.0 FOUNDATIONS
Mat foundations for self-supporting structures shall be sized so that the reactions form
the serviceability loading combination result in compressive soil bearing stress over the
full plan dimension of the mat.
Drilled shaft or pile foundations subjected to lateral load shall be designed considering
repetitive loading soil conditions.
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14.0 MAINTENANCE AND CONDITION ASSESMENT
ANSI/TIA-222-G-DS1-2011
DRAFT 3-29-2011 Rev 0
The maintenance and condition assessment of SWT supporting structure shall be in
accordance with TIA except the recommended interval period is 6 months for all
supporting structure types.
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ANSI/TIA-222-G-DS1-2011
DRAFT 3-29-2011 Rev 0
REFERENCE TABLES
Table 4-1
Force Coefficients (C F ) for Pole Structures without Attachments
(Refer to TIA for Pole Structures with Attachments)
C
Mph-ft
[m/s-m]
< 32 [4.4]
(Subcritical)
Round 18-Sided 16-Sided 12-Sided 8-Sided
1.2 1.2 1.2 1.2 1.2
32 to 64 162/(C) 1.42 59.3/(C) 1.13 25.7/(C) 0.884 5.06/(C) 0.415 1.2
[4.4 to 8.7]
(Transitional)
> 64 [8.7]
(Supercritical)
[9.64/(C) 1.42 ] [6.29/(C) 1.13 ] [4.41/(C) 0.884 ] [2.21/(C) 0.415 ] [1.2]
0.45 0.55 0.65 0.90 1.2
C = (I K zt K z ) 0.5 (V)(D) for D in ft [m], V in mph [m/s]
I = TIA importance factor for wind loading
K zt = TIA topographic factor
K z = TIA velocity pressure coefficient
V is the 50-year, 3-second gust basic wind speed for the loading condition under
investigation.
D is the pole outside diameter for rounds or the outside point-to-point diameter for
polygons.
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ANSI/TIA-222-G-DS1-2011
DRAFT 3-29-2011 Rev 0
REFERENCE TABLES
Table 11-1
Fatigue Importance Factors, I f
TIA Structure Fatigue
Classification Importance
Factor, I f
I 0.70
II 1.00
III 1.35
Table 11-2
Latticed Structure Limitations
AWEA Turbine
Power Rating
Maximum
Effective
Slenderness
of Members
Minimum
Gusset
Plate
Thickness
Up to 10 kW 200 3/16” [5 mm]
Over 10 kW to 25 kW 185 1/4” [6 mm]
Over 25 kW 175 3/8” [10 mm]
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ANSI/TIA-222-G-DS1-2011
DRAFT 3-29-2011 Rev 0
REFERENCE TABLES
Table 12-1
Resistance Factors for Extreme Loadings
(Other Structural Materials)
Type of Failure
Resistance Factor
Yielding of ductile material 0.90
Local or global buckling 0.85
Fracture of brittle or ductile material 0.75
Table 12-2
Resistance Factors for Fatigue Loading
(Other Structural Materials)
Basis of Nominal Stress Range
50% survival probability with coefficient
of variation ≥ 15%
50% survival probability with coefficient
of variation < 15%
Test data with basis of 95% survival
probability with a 95% confidence level
Resistance
Factor
0.60
0.67
0.85
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ANSI/TIA-222-G-DS1-2011
DRAFT 3-29-2011 Rev 0
ANNEX A: REFERENCES (Informative)
AASHTO, “Standard Specifications for Structural Supports for Highway Signs,
Luminaires, and Traffic Signals”, 5 th Edition, American Association of State Highway
and Transportation Officials, 2009.
AISC, “Steel Construction Manual”, 13 th
Construction, Inc., 2005.
Edition, American Institute of Steel
ASCE, “Minimum Design Loads for Buildings and Other Structures”, ASCE/SEI 7-05,
American Society of Civil Engineers, 2005.
AWEA, “AWEA Small Wind Turbine Performance and Safety Standard”, AWEA 9.1-
2009, American Wind Energy Association, 2009
AWS, “Structural Welding Code - Steel”, AWS D1.1/D1.1M:2010, American Welding
Society, 2010.
IEC, “Wind Turbine-Part 1: Design Requirements”, IEC 61400-1, International
Electrotechnical Commission, Third Edition 2005-08.
IEC, “Wind Turbine-Part 2: Design Requirements for Small Wind Turbines”, IEC 61400-
2, International Electrotechnical Commission, Second Edition 2006-03.
TIA, “Structural Standard for Antenna Supporting Structures and Antennas”, ANSI/TIA-
222-G, Telecommunications Industry Association, 2005.
17