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Letter, Valmont 091914 & 021915 valmont q STRUCTURES February 19,2015 Town of Southhold Building&Planning Departments Town of Southold Annex Building 54375 Route 25 Southold, NY 11971 Re: Design and failure modes for a 120-ft Tapered Monopole w/Cell Silo Quality of Steel and Fabrication of a Monopole Structure Valmont Quote No.211580-03 Site Location:Mattituck,NY Pole Designed with a Theoretical Fall Radius of 51-ft To Whom it May Concern: As detailed below,the 120 ft multi-carrier disguised monopole proposed by Elite Towers, LP,at the captioned site,and as depicted in Construction Drawings prepared by Herbst Musciano, Revision 8,dated 9/1/2014,will comply with all applicable federal,state and local structural standards.Valmont,as manufacturer of the monopole,offers the following in order to assure you of the high quality of all Valmont products: Tapered Monopole Desion Standards and Failure Modes: • Communications monopole structures designed by Valmont are sized in accordance with the latest governing revision of the ANSI/TIA 222,which is a referenced standard for communication structures by the New York State Building Code, unless otherwise requested by our customer. This standard has been approved by ANSI/ASCE, which has dealt with the design of antenna support structures for over 40 years. The TIA standard, based on provisions of this nationally known specification, has a long history of reliability. At its core philosophy is its first and foremost priority to safeguard and maintain the health and welfare of the public. • The TIA standard designates a minimum wind loading for each county in the United States. Valmont uses the wind loading listed in the TIA standard unless a greater value is specified by our customer. Structures are also designed for radial ice at a code specified reduced design wind loading. Code designated coefficients are used to ensure that the structure will survive the designed wind speed. The structure can usually survive even a greater wind load than the basic design wind speed because of these conservative coefficients. • Design and loading assumptions that are used for the analyses of these structures are very conservative in nature when compared to other codes,which makes structural failure highly improbable. • Failure of a steel monopole occurs when a point is reached where the induced stresses exceed the yield strength of the material. At this point,the deflections induced in the material are no longer temporary. Hence,a permanent deflection in the monopole would exist. • The term failure above refers to local budding at a designated point on the pole. Local buckling does not cause a free falling pole;rather it relieves the stresses from the pole at this location. Monopoles are flexible,forgiving structures,which are not generally susceptible to damage by impact loads such as wind gust or earthquake shocks. • When local buckling occurs,a relatively small portion of the shaft distorts and"kinks"the steel. When the pole begins to bend the exposure area is reduced and therefore,the force due to wind is decreased as well. Even though buckling exists,the cross section of the pole is capable of carrying the entire vertical load. Therefore,wind induced loads could not conceivably bring this type of structure to the ground due to the excellent ductile properties,design criteria,and failure mode. • Valmont's communication poles have proven to be very reliable products. Valmont has provided structures that have performed well during earthquakes in California,hurricanes in the South(including Page 1 Of 2 Specialty Structures Group,Valmont Industries,Inc. 3575 25'"Street Salem,OR 973020423 USA Toll Free:800-547-2151 Fax:503-316-2040 www.valmont.com i F valmont STRUCTURES Hugo,Andrew,Opal and Katrina),and a number of tornadoes. In over 25 years of engineering and fabricating thousands of monopoles,to our knowledge Valmont has never experienced an in service failure of a communication pole due to weather induced overloading,even though,as in the cases of Hurricanes Hugo,Andrew and Katrina,the wind speeds exceeded the design wind speed. We use the latest standards,wind speed information, and sophisticated analytical tools to ensure that we maintain our unblemished record for quality. Valmont Quality of Steel and Manufacturina: • Monopoles are fabricated from ASTM A572 Grade 65 material with a controlled silicon content of 0.06% maximum to ensure a uniform galvanized coating. The base material is fabricated from Grade 50 material. All plate material meets a V-Notch toughness requirement of 15 ft-lbs.@-20 degrees Fahrenheit. By meeting the strict toughness requirement,monopoles are best suited to resist the cyclictfatigue type loading(i.e.wind induced loading)these structures exhibit. • Valmont's anchor bolts are fabricated from A615 Grade 75 material. The bolts are typically 2%in diameter,made from#18J bar stock. Anchor bolts come complete with five(5)A194 Grade 2H hex nuts. • For the past 40 years,our company has always guaranteed the quality of the steel used in building our structures. Material Certifications are available on all material at the time of fabrication. Fabrication of the monopole is performed in accordance with the provisions of the AISC Manual of Steel Construction and ASCE's Design of Steel Transmission Pole Structures. All welding and inspection is in accordance with the American Welding Society's Specification D1.1-latest revision. Testing and inspection reports are available upon request at the time of fabrication. In addition,this monopole can be designed to theoretically fail at approximately the 69-ft elevation by purposely over designing the pole sections below this point.In the unlikely event the pole were to fail at this point,the significant loading reduction caused by the removal of the tower wind area and weight above would greatly reduce any chance that the remaining tower would have any structural damage,thereby providing a theoretical failure radius of approximately 51-ft as designed. I hope these comments address any issues that you might encounter relative to the anticipated performance of the monopole structure and the quality of steel fabrication. In consideration of the parameters above and given the fact that the replacement pole is being located in approximately the same location as the existing pole(within approximately 3'),we respectfully request that the Planning Board waive the"fall zone" requirements of the Code. If you have additional questions or comments, I may be reached at(503)589-6618. Sincerely, OF N-S David Casey �,1 AM y Project Enginee � 9�C ca yti y`�FpP 8 ro.N FEB 2 2015 Page 2 Of 2 Specialty Structures Group,Valmont Industries,Inc. 3575 25w Street Salem,OR 97302-1123 USA Toll Free:800-547-2151 Fax:503-316-2040 www.valmont.com val ntV STRUCTURES September 19,2014 Town of Southhold Building&Planning Departments Town of Southold Annex Building 54375 Route 25 Southold, NY 11971 Re: Design and failure modes for a 120 ft Tapered Monopole w/Cell Silo Quality of Steel and Fabrication of a Monopole Structure Valmont Quote No.211580-03 Site Location:Mattituck, NY To Whom it May Concern: As detailed below,the 120 ft multi-carrier disguised monopole proposed by Elite Towers, LP,at the captioned site,and as depicted in Construction Drawings prepared by Herbst Musciano,Revision 8,dated 911/2014,will comply with all applicable federal,state and local structural standards.Valmont,as manufacturer of the monopole,offers the following in order to assure you of the high quality of all Valmont products: Tapered Monopole Design Standards and Failure Modes: • Communications monopole structures designed by Valmont are sized in accordance with the latest governing revision of the ANSI/TIA 222,which is a referenced standard for communication structures by the New York State Building Code, unless otherwise requested by our customer. This standard has been approved by ANSI/ASCE, which has dealt with the design of antenna support structures for over 40 years. The TIA standard, based an provisions of this nationally known specification, has a long history of reliability. At its core philosophy is it's first and foremost priority to safeguard and maintain the health and welfare of the public. • The TIA standard designates a minimum wind loading for each county in the United States. Valmont uses the wind loading listed in the TIA standard unless a greater value is specified by our customer. Structures are also designed for radial ice at a code specified reduced design wind loading. Code designated coefficients are used to ensure that the structure will survive the designed wind speed. The structure can usually survive even a greater wind load than the basic design wind speed because of these conservative coefficients, • Design and loading assumptions that are used for the analyses of these structures are very conservative in nature when compared to other codes,which makes structural failure highly improbable. • Failure of a steel monopole occurs when a point is reached where the induced stresses exceed the yield strength of the material. At this point,the deflections induced in the material are no longer temporary. Hence,a permanent deflection in the monopole would exist. • The term failure above refers to local buckling at a designated point on the pole. Local buckling does not cause a free falling pole;rather it relieves the stresses from the pole at this location. Monopoles are flexible,forgiving structures,which are not generally susceptible to damage by impact loads such as wind gust or earthquake shocks. • When local buckling occurs,a relatively small portion of the shaft distorts and"kinks"the steel. When the pole begins to bend the exposure area is reduced and therefore,the force due to wind is decreased as well. Even though buckling exists,the cross section of the pole is capable of carrying the entire vertical load. Therefore,wind induced loads could not conceivably bring this type of structure to the ground due to the excellent ductile properties,design criteria,and failure mode. • Valmont's communication poles have proven to be very reliable products. Valmont has provided structures that have performed well during earthquakes in California,hurricanes in the South(including Hugo,Andrew, Opal and Katrina),and a number of tornadoes. In over 25 years of engineering and fabricating thousands of monopoles,to our knowledge Valmont has never experienced an in service Page I of 2 Specialty Structures Group,Valmont Industries,Inc. 3575 25'Street Salem,OR 97302-1123 USA Toll Free:800-547.2151 Fax:503-316-2040 www.valmont.com val ntV STRUCTURES failure of a communication pole due to weather induced overloading,even though,as in the cases of Hurricanes Hugo,Andrew and Katrina,the wind speeds exceeded the design wind speed. We use the latest standards,wind speed information,and sophisticated analytical tools to ensure that we maintain our unblemished record for quality. Valmont Quality of Steel and Manufacturing: • Monopoles are fabricated from ASTM A572 Grade 65 material with a controlled silicon content of 0.06% maximum to ensure a uniform galvanized coating. The base material is fabricated from Grade 50 material. All plate material meets a V-Notch toughness requirement of 15 ft-lbs.@-20 degrees Fahrenheit. By meeting the strict toughness requirement,monopoles are best suited to resist the cyclic/fatigue type loading(i.e.wind induced loading)these structures exhibit. • Valmont's anchor bolts are fabricated from A615 Grade 75 material. The bolts are typically 2%in diameter, made from#1&i bar stock. Anchor bolts come complete with five(5)A194 Grade 2H hex nuts. • For the past 40 years,our company has always guaranteed the quality of the steel used in building our structures. Material Certifications are available on all material at the time of fabrication. Fabrication of the monopole is performed in accordance with the provisions of the RISC Manual of Steel Construction and ASCE's Design of Steel Transmission Pole Structures. All welding and inspection is in accordance with the American Welding Society's Specification D1.1-latest revision. Testing and inspection reports are available upon request at the time of fabrication. I hope these comments address the issues that you might encounter relative to the anticipated performance of monopole structures and quality of steel fabrication. If you have additional questions or comments, I may be reached at(503)589-6618. Sincerely, William R.Heiden, 111, P.E. Manager of Engineering Ne �,��,IAM co ;e -A- LU EP 2 2 2014 Page 2 of 2 Specialty Structures Group,Valmont Industries,Inc. 3575 25'Street Salem,OR 97302-1123 USA Tall Free:800.547-2151 Fax:503-316-2040 www.valmont.com