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American Iron and Steel Institute American Iron and Steel Institutes Technical Session Steel Distribution Poles - The Material of the Future - presented.

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Presentation on theme: "American Iron and Steel Institute American Iron and Steel Institutes Technical Session Steel Distribution Poles - The Material of the Future - presented."— Presentation transcript:

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2 American Iron and Steel Institute American Iron and Steel Institutes Technical Session Steel Distribution Poles - The Material of the Future - presented by - Richard F. Aichinger, PE Manager of Engineering, Utility Products Valmont Industries, Inc. Design & Testing of Steel Poles

3 American Iron and Steel Institute Designing For Equivalency Equivalency to what? –Expected Strength –Expected Life –Expected Performance Deflection Handling Field Use

4 American Iron and Steel Institute Designing For Equivalency Most pole used to date have been wood How do you design a Steel wood pole? –You cant … but you dont want to –Instead you design a pole that meets minimum strength and performance requirements every time

5 American Iron and Steel Institute Designing For Equivalency How do you design a Steel Distribution Pole? –ANSI Standards: ANSI 05.1 National Electric Safety Code (ANSI C-2) –ASCE Manual 72 –Material & Manufacturing Proven Reliability –Testing and Proven Product Experience

6 American Iron and Steel Institute ANSI 05.1 Provides performance and quality criteria for wood poles of various species Provides strength requirements which define the various pole Class definition (Class 6 to H-6) –Defined by a Capacity Loading to be applied 2 feet from the pole top Provides direct embedment depth

7 American Iron and Steel Institute National Electrical Safety Code (ANSI C-2) A Safety Code By default, also a Design Code –Provides for Design considerations for various line conditions (ice, wind + ice, wind) –Provides for Construction Grades to differentiate the allowable risk accepted in the design

8 American Iron and Steel Institute National Electrical Safety Code (ANSI C-2) A Little History: Provided for loading and strength since the early 1900s to present Early editions were based on ultimate strength of materials Steel was first to be changed to Load Factor in 1941

9 American Iron and Steel Institute National Electrical Safety Code (ANSI C-2) 1941 Summary: –MaterialGrade BGrade C Steel wood25%37.5% –(equiv. OLF)(4.0)(2.67)

10 American Iron and Steel Institute National Electrical Safety Code (ANSI C-2) 1973 Wood was modified: –MaterialGrade BGrade C Steel wood25%50% –(equiv. OLF)(4.0)(2.0) –Familiar? –wood is now lower than steel in Grade C Edition introduced Strength Factors

11 American Iron and Steel Institute National Electrical Safety Code (ANSI C-2) 1997 Edition Grade B: Strength Factor Equiv. O.L.F. Load Type Overload Steel Wood Steel Wood Ratio Vertical Transverse Wind Tension

12 American Iron and Steel Institute National Electrical Safety Code (ANSI C-2) 1997 Edition Grade C: Strength Factor Equiv. O.L.F. Ratio Load Type Overload Steel Wood Steel Wood Vertical Transverse Wind 2.2 (steel) (wood) Tension 1.1 (steel) (wood)

13 American Iron and Steel Institute ASCE Manual 72 The Steel Pole Design Guide Provides for the best practices of the industry Provides for the Design Requirements equated to: –AISC –ACI –AWS

14 American Iron and Steel Institute Designing For Equivalency Equivalent Wood Pole Loading (B): –ANSI Load x 2.5/4.0 ANSI 05.1WorkingEquivalent Pole Class Loading Load Steel Load # 925 # 2313 #

15 American Iron and Steel Institute Designing For Equivalency CLASS 4 Pole has ANSI rated capacity of 2400#. –GRADE B CONSTRUCTION: WOOD O.L.F.4.0 STEEL O.L.F.2.5 STEEL RATED LOAD BECOMES 2400# x 2.5/4.0 = 1500# –GRADE C CONSTRUCTION: WOOD O.L.F.2.0 STEEL O.L.F.2.2 STEEL RATED LOAD BECOMES 2400# x 2.2/2.0 = 2640#

16 American Iron and Steel Institute Designing For Equivalency CLASS 4 Pole has ANSI rated capacity of 2400#. –GRADE B CONSTRUCTION: WOOD O.L.F.4.0 STEEL O.L.F.2.5 STEEL RATED LOAD BECOMES 2400# x 2.5/4.0 = 1500# –GRADE C (Expected NESC Change for 2002) WOOD O.L.F.2.06 STEEL O.L.F.1.75 STEEL RATED LOAD BECOMES 2400# x 1.75/2.06 = 2039#(vs. 2640#)

17 American Iron and Steel Institute Designing For Equivalency Steel Allows for Designs that Consistently meet strength requirements by varying diameter and thickness ASCE Manual 72 provides criteria for Local Buckling of Tubular Steel –Proven through years of use in other products –Verified by EPRI and manufacturer testing Provides a pole that is consistent by design

18 American Iron and Steel Institute Designing For Life Steel Allows for the Design of a Product that can be protected against deterioration –Galvanizing provides a proven inside/out protection for most environments –An additional groundline barrier coating provides extra protection at the most corrosive location –When damaged by overload conditions, Steel will tend to locally yield rather than break or collapse, often times allowing the line to remain in service

19 American Iron and Steel Institute Designing For Performance Deflection of steel poles are normally less than the equivalent wood pole based on the pole size defined by ANSI 05.1 The following graph shows a representative comparison indicating the deflection of a Steel versus wood poles

20 American Iron and Steel Institute Load Deflection of Steel vs. Wood Poles (40 Class 4, NESC Grade B)

21 American Iron and Steel Institute Designing For Performance Weight of steel poles are normally much less than the equivalent wood pole providing added savings for field handling and maneuvering The following chart is a representative comparison of the weight of wood poles versus Steel Poles

22 American Iron and Steel Institute Weight Comparison of Wood to Steel

23 American Iron and Steel Institute Designing For Performance Additionally, Steel can be Designed for true design applications wood is seldom correctly considered for: –Guyed angles and corners NESC requirements: –Unguyed angles and corners Steel provides the necessary strength and flexibility of size and application

24 American Iron and Steel Institute Designing For Reliability Steel Poles have been successfully used: –for over 30 years for the Electric Utility industry –for over 40 years with the same product in other industries (lighting and traffic) Fabrication and Quality systems have evolved to keep up with customer demand, technology, and increasing Design sophistication

25 American Iron and Steel Institute Designing Proven by Testing Steel Poles have been tested for as long as Steel Poles have been fabricated. But there is a difference: –Steel Poles are tested to Verify Design strength is attained as a Minimum –wood poles are tested to determine the mean rupture strength

26 American Iron and Steel Institute Designing Proven by Testing Steel Distribution Poles have been tested by independent firms (EDM in Fort Collins) and by the manufacturers using controlled conditions and sophisticated systems. –Strength / Buckling tests to verify design acceptance for conditions including: full tube sections tube sections with many cut holes to verify that condition attachment and guy hardware loading –All showing the Strength and Reliability of Steel

27 American Iron and Steel Institute Post Insulator Test On Steel Pole

28 American Iron and Steel Institute Guy Attachment Test On Steel Pole

29 American Iron and Steel Institute EPRI Test On 70 Class 2 Steel Pole

30 American Iron and Steel Institute Testing at EPRI (Class 2) and EDM (Class 3 & 5)

31 American Iron and Steel Institute Steel Distribution Poles - The Material of the Future

32 American Iron and Steel Institute Steel Distribution Poles - The Material of the Future In Conclusion: Steel Distribution Poles Provide –Expected Strength –Expected Life –Expected Performance in Deflection Handling Field Use


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