Utility Industry Anchor Design and Maintenance Manual

96 Pages·2014·17.21 MB·English

by  Mike Allen

“Designed and Engineered to Perform”
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www.getecp.com 1-866-327-0007 ©2013 Earth Contact Products
Utility Industry
Anchor Design and
Maintenance Manual
By: Donald J. Clayton, PE
“Designed and Engineered to Perform”
© 2013 Earth Contact Products, LLC. All Rights Reserved.
This material may not be reproduced in any form without the written permission of Earth Contact Products, LLC. Any
unauthorized uses of the material and inventions disclosed herein or reproductions or copies of the pages of this document are
hereby prohibited. Such uses would be deemed infringement of Earth Contact Products’ intellectual property rights and will
be prosecuted to the full extent of the law.
ECPUTILITY
Is a division of
Earth Contact Products, LLC
Company Office and Manufacturing Facility
15612 South Keeler Terrace, Olathe, Kansas 66062
913 393-0007- FAX [phone]
Toll Free– 866 327-0007
www.earthcontactproducts.com
Earth Contact Products, LLC reserves the right to change design features, specifications and products without notice,
consistent with our efforts toward continuous product improvement. We also make changes and corrections to the technical
design text consistent with the state of the art. Please check with Engineering Department, Earth Contact Products to verify
that you are using the most recent design information and product specifications.
First Printing–07/2011
Second Printing–12/2013 (revised edition)
Preface
Earth Contract Products designs and manufactures quality foundation anchors and support products at
competitive prices. The purpose of this manual is to assist the reader to prepare preliminary designs for
ECP product selections that will most economically fit a given application. The manual also provides
installation guidance and product selection. In this manual we have attempted to take the highly
technical engineering theories and distill them into a veryuser friendly format. We have reduced many
complicated equations into simpler terms that relate to the most typical applications where our products
have been used. In addition, we have included many graphs and tables that can help the reader to
obtain solutions with a minimum of mathematical effort. The reader will find clear and simple
explanations, data tables, and many relevant examples in this manual. By taking some knowledge of
basic theory to arrive at a relatively accurate product design by following step by step instructions,
tables and graphs when using this manual. This manual is in no way intended to replace professional
engineering input and judgment; in addition, we require incorporating a factor of safety suitable to the
project for each and every preliminary design. We highly recommend that you seek professional
engineering input on complicated applications. We also consider it good practice to perform a field
load test on any heavily loaded anchorsorfor placements incritical applications.
Utility Industry Anchor Design and MaintenanceManual © 2013 Earth Contact Products, L.L.C
2013-11 Pagei All rights reserved
Table of Contents
Chapter 1 – Introduction to ECP Helical Torque Anchors™
for Electric Utility Applications 1
Introduction 3
ECP Torque Anchors™ 3
Torque Anchor™ Components 4
Product Benefits 4
Product Limitations 5
Soil Types 5
Table 1–Torque Anchor™ Product Designations 5
Table2–Capacities of ECP Torque Anchors™ 5
Product Data 6
Power Installed Torque Anchors™ (PITA) 6
Extreme Power Installed Torque Anchors™ (PITA) 6
HD Extreme Power Installed Torque Anchors™ (PITA) 6
Cable Attachment Eyes 7
Pita Accessories 7
Round Corner Square Bar ECP Torque Anchors™ 8
Product Limitations 9
Soil Types 9
Table 3–Soil Classification Table 9
Effects of Water Table Fluctuation and Freeze Thaw Cycle 10
Anchor Holding Capacity 10
Chapter 2 – Tension Design for ECP Helical Torque Anchors™ 13
Table4–Symbols Used in this Manual 14
Design Criteria 14
Preliminary Design Guidelines 15
Deep Foundations 15
Equation1(Ultimate Theoretical Capacity) 16
Soil Behavior 16
Cohesive Soil (Clay) 16
Table 5- Cohesive Soil Classification 16
Undrained Shear Strength 17
Cohesive Bearing Capacity Factor– “N” 17
c
Equation 1a(Ultimate Capacity– Cohesive Soil) 17
Cohesionless Soil (Sand and Gravel) 17
Soil Overburden Pressure– “q” 17
Table 6-Properties of Cohesive Soil 17
Table7-CohesionlessSoil Classification 17
Cohesionless Bearing Capacity Factor– “N ” 18
q
Table8-Properties of Cohesionless Soil 18
Utility Industry Anchor Design and Maintenance Manual © 2013 Earth Contact Products, L.L.C
2013-11 Pageii All rights reserved
Equation1b(Ultimate Capacity– Cohesionless Soil) 18
Helical Torque Anchor™Design Considerations 18
Projected Areas of Helical Plates 18
Allowable Helical Plate Capacity 18
Table9-Projected Areas of Helical Torque Anchor™ Plates 18
Table 10-Average Ultimate Mechanical Helical Plate Capacities 19
Installation Torque 19
Figure 1– Torque Efficiency 19
Torque Efficiency Factor– “k” 19
Table 11- TorqueEfficiencyFactor– “k” 19
Equation 2(Helical Installation Torque) 20
Equation 2a(Torque Efficiency Factor) 20
Minimum Embedment Depth 20
Figure 2. Minimum Embedment depth to insure
sufficient soil overburden for resistance to pull out. 20
Preventing “Pull Out” in Tension Applications 21
Torque Anchor™ Installation Limits 21
Shaft Strength 21
Graph 1–Ultimate Capacities for Structural Applications 22
Guy Anchoring Design 23
Introduction to Guy Anchoring 23
Guy Loads 23
Angle Line Loads 23
Equation3(Dead End Load on Pole) 23
Torque anchor™ Holding Capacity Estimates 23
Graph 2–Guy Anchor Holding Capacity 25
Graph 3–Ultimate Guy Anchor Capacities 26
Design Example 1– Guy Load 27
Design Example 2– Guy Anchor in Cohesive (Clay) Soil 28
Design Example 3– Guy Anchor in Cohesionless (Granular) Soil 31
Table 12-Ultimate Strength of Conductors 33
Table 13- Bisected Line Load to Be Guyed 34
Table 14-Guy Load 35
Table 15-Breaking Strength of Stranded Guy Wire 36
Chapter 3 – Compressive Design for ECP Helical Torque Anchors™ 37
Compressive Helical Torque Anchor™ Design Considerations 38
Table16- ECP Torque Anchor™ Product Designations 38
Table 17– Capacities of ECP Torque Anchor™ 38
Product Data 39
Round Corner Square Bar ECP Torque Anchor™ Lead Sections 39
Tubular Shaft ECP Torque Anchors™ 40
Light Pole Anchor Configurations 41
Utility Industry Anchor Design and Maintenance Manual © 2013 Earth Contact Products, L.L.C
2013-11 Pageiii All rights reserved
Foundation Grillages 42
Tubular Pile Caps 42
Preventing “Punch Through” in Compression 42
Minimum Embedment Depth 42
Torque Anchor™ Compressive Installation Limits 43
Shaft Strength 43
Buckling Loads in Weak Soil 43
Table 18–Torque Anchor™ Shaft Stiffness Comparison 44
Table 19–Conservative Critical Buckling Load Estimates 44
Equation4(Critical Buckling Load) 44
Shaft Stiffness 44
Graph4– Ultimate loads–Piles in air orwater with
no lateral support to the grout filledshaft 45
Torque Anchor™ Compressive Capacity Estimates 45
Graph 5– Torque Anchor™ Holding Capacity (8”, 10”, 12” & 14” dia.) 47
Graph 6– Torque Anchor™ Holding Capacity (8-8”, 8-10”, 10-10” & 10-12” dia.) 47
Graph 7– Torque Anchor™ Holding Capacity
(12-14”, 8-10-12”, 10-12-14” & 12-14-14” dia.) 48
Graph 8– Torque Anchor™ Holding Capacity
(8-10-12-14”, 10-12-14-14”, & 12-14-14-14” dia.) 48
Design Example 4–Transmission Tower in Cohesive (Clay) Soil 49
Design Example 5– Transmission Tower in Cohesionless (Granular) Soil 52
Design Example 6– Transmission Tower in Wetland Soil 54
Chapter 4 – Installation Guidelines and Testing Procedures for
ECP Helical Torque Anchors™ 57
Hydraulic Torque Motors 58
Installation Torque 58
TorqueEfficiency Factor – “k” 58
Equation 5(Helical Installation Torque) 59
Equation 5a(Torque Efficiency Factor) 59
Table 15– Installation Torque Factor– “k” 59
Determining Installation Torque 59
Twisting of the Solid Square Bar 59
Shear Pin Hub 59
Single Pressure Gauge 59
Dual Pressure Gauges 60
Strain Gauge Monitor 60
Converting Motor Pressure to Shaft Torque 60
Equation 7 (Installation Motor Output Torque) 60
Table 20–Hydraulic Torque Motor Specifications 61
Graph9–Motor Output Torque vs Ultimate Capacity 61
Torque Motor Accessories 62
ECP Smart Anchor Monitor (SAM) and Assembly Configuration 62
Utility Industry Anchor Design and Maintenance Manual © 2013 Earth Contact Products, L.L.C
2013-11 Pageiv All rights reserved
ECP Hydraulic Torque Motor Performance Curves 63
Graph10–Pro-Dig PDU78 Two Speed Gear Motor
Differential Pressure at Motor vs. Motor Output Torque 63
Graph11– Pro-Dig PDU78 Two Speed Gear Motor
Hydraulic Flowthrough Motor vs.Output Shaft Speed 63
Graph12– Pro-Dig PDU76 & PDU 76B Single Speed Gear Motors
Differential Pressure at Motor vs. Motor Output Torque 64
Graph13– Pro-Dig PDU76 & PDU 76B Single Speed Gear Motors
Hydraulic Flowthrough Motorvs. Output Shaft Speed 64
Design Example7–Motor Output Torque 65
Design Example8–Estimated Ultimate Capacity 65
ECP Helical Guy Anchor Installation Procedure 67
ECP PITA Anchor & Extreme PITA Anchor Installation Procedure 69
Structural CompressivePileand/or Tensile Helical Anchor InstallationProcedure 71
Torque Anchor™ Installation Record (Sample Form) 73
Field Test Procedures for Static Axial Compression and Tensile Loads 74
Basic Procedure for Quick Tension or Compression Tests 75
Field Load Test Report (Sample Form) 76
Chapter5 – Corrosion Considerations 77
Corrosion Life Expectancies 78
Steel Underground– How Long Will It Last? 78
Soil Resistivity 78
Table 21–Soil Classification Table- Resistivity 78
Table 22–Soil Resistivity and Relative Corrosivity Rating 78
Soil pH 78
Graph13–The Effect of pH on Corrosion of Iron 79
Zinc Galvanizing for Corrosion Protection 79
Zinc Galvanizingfor Corrosion Protection 79
Graph 14– The Effect of pH on Corrosion of Zinc life of Galvanized Coating 79
Life of Galvanized Coating 79
Graph 15– Corrosion Life of Galvanized Steel in Neutral Soil (pH = 7) 80
Graph 16– Corrosion Life of Galvanized Steel in Corrosive Soil
(pH< 4.5 or pH > 10.5) 80
Graph 17–Estimated Life of Galvanized Coating PITA Rods & Adapters
Hot Dip Galvanizing 81
Table 23– ECP Torque Anchor™ Estimated Average Life Expectancy at Full Load 82
Hot Dip Galvanizing 83
Design Example 7– Corrosion Life of Tubular Shaft 83
Manufacturer’s Warranty 87
Earth Contact Products, LLC reserves the right to change design features, specifications and products without notice,
consistent with our efforts toward continuous product improvement. We also make changes and corrections to the technical
design text consistent with the state of the art. Please check with Engineering Department, Earth Contact Products to verify
that you are using the most recent design information and product specifications.
Utility Industry Anchor Design and Maintenance Manual © 2013 Earth Contact Products, L.L.C
2013-11 Pagev All rights reserved
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Chapter 1 ors
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Introduction to
™
ECP Helical Torque Anchors
for Electric Utility Applications
 PITA Helical Torque Anchors™
 HD Extreme PITA Torque Anchors™
 Solid Square Shaft Torque Anchors™
 Tubular Shaft Torque Anchors™
“Designed and Engineered to Perform”
Introduction toUtility Industry Anchor Design © 2013 Earth Contact Products, L.L.C.
2013-11 Page1 All rights reserved
© 2013 Earth Contact Products, LLC. All Rights Reserved.
This material may not be reproduced in any form without the written permission of Earth Contact Products, LLC. Any
unauthorized uses of the material and inventions disclosed herein or reproductions or copies of the pages of this document are
hereby prohibited. Such uses would be deemed infringement of Earth Contact Products’ intellectual property rights and will be
prosecuted to the full extent of the law.
Earth Contact Products, LLC
Corporate Office and Manufacturing Facility
15612 South Keeler Terrace, Olathe, Kansas 66062
913 393-0007- FAX [phone]
Toll Free– 866 327-0007
www.earthcontactproducts.com
Earth Contact Products, LLC reserves the right to change design features, specifications and products without notice, consistent
with our efforts toward continuous product improvement. Please check with Engineering Department, Earth Contact Products to
verify that you are using the most recent information and specifications.
Technical Design Assistance
Earth Contact Products, LLC. has a knowledgeable staff that stands ready to help you with understanding how to
prepare preliminary designs, installation procedures, load testing, and documentation of each placement when
using ECP Torque Anchors™. If you have questions or require engineering assistance in evaluating, designing,
and/or specifying Earth Contact Products, please contact us at 913 393-0007, Fax at 913 393-0008.
Introduction toUtility Industry Anchor Design © 2013 Earth Contact Products, L.L.C.
2013-11 Page2 All rights reserved
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Introduction nq™
ors
Screw piles have been in use for more than 162 19th and early 20th centuries. They mainly ctiToor
years. In 1838 a lighthouse was built upon screw supported structures and bridges over weak or wet ul h
dac
piles designed by an Irish engineer, Alexander soil. ocn
rliA
Mitchell. In 1863, Eugenius Birch designed the Hydraulic torque motors became available in the ntHe
Brighton West Pier in Brighton, England. These 1960’s, which allowed for easy and fast I
piers are still in use 140 years later. The original installation of screw piles. Screw piles soon
screw piles were installed at 10 feet per hour using became the favored product for resisting tensile
eight 20 foot long torque bars with the force of 32 forces. Soon electric utility companies began to
to 40 men. use screw piles for tie down anchors on
In the United States, the Thomas Point Shoal transmission towers and for guy wires on utility
Lighthouse on Chesapeake Bay, Maryland is the poles. After implementing helical gear motors in
only remaining lighthouse built upon helical screw the 1960's, the electric utility companies became a
piles that is still situated at its original location leading consumer of helical anchors due to the
near Annapolis, Maryland. The lighthouse has a easy and fast installation of helical screw piles.
hexagonal shape measuring 35 feet across, and it Initially the helical screw piles were used as guy
is still supported by seven original helical screw wire anchors for utility poles and subsequently as
piles. The Thomas Point Shoal Lighthouse was tie down anchors for transmission towers. The
first put into operation on November 20, 1875. combination of the gear motor and the helical
anchor provided excellent foundation support for
utility infrastructures. Such applications are
particularly beneficial in times of major storm
damage where a rapid foundation support system
is necessary to restore power to customers.
Helical screw piles are ideal for applications
where there is a need to resist both tensile and
axial compressive forces. Some examples of
structures having such combination forces are
metal building foundations, canopy supports and
monopole telecommunication tower foundations.
Current uses for helical screw pile foundations
include foundations for commercial and residential
structures, lighting standards, retaining walls
Thomas Point Shoal Lighthouse tieback anchors, guy wire anchors, failed
The helical screw piles that support the structure foundation restorations, pipeline and pumping
consist of ten inch diameter wrought iron shafts equipment supports, elevated walkways, bridge
with cast iron helical abutments, and numerous other uses in the electric
screw flanges at the utility industry.
end of the shafts. At
Thomas Point, the ECP Torque Anchors™
screw piles were
ECP Torque Anchors™ are a part of the complete
advanced into to sandy
product line of screw piles, steel piers and
bottom of Chesapeake
foundation support products manufactured by
Bay a distance of 11-
Earth Contact Products, LLC, a family owned
1/2 feet. The light is
company based in Olathe, Kansas.
mounted 43 feet above
the surface of the Our 100,000 square foot state of the art
water. manufacturing facility produces all components
and steel assemblies. Earth Contact Products uses
Sporadic use of screw
only certified welders and robotics for quality
piles has been docu-
Cast iron coupling at fabrication. The only processes not done in our
mented throughout the
Thomas Point
facility are galvanization and hot forge upsetting
Lighthouse
Introduction toUtility Industry Anchor Design © 2013 Earth Contact Products, L.L.C.
2013-11 Page3 All rights reserved