4.1 - Laserfiche WebLink

Home Browse Search

11--gUG.25.1998— 2:26PM COMM TWR 402 359 5856 COMM TWR NO.760 P. 1%3 AUG 25 '98 01: 16PM • VALMONT MICROFI.ECT Valmont Industries,Inc.•West Highway 275•P.O.Box 358 Valley,Nebraska 68064-0358 U.S.A.•(402)359-2201 August 25, 1998 US West Wireless,LLC 426 North Fairview Avenue Suite 101 St.Paul,MN 55104 Attention: Mr.Adrian Schottroff Subject: Failure Modes for Poles and a Description of the Design Criteria US West Wireless Site: SCL005 Valmont Order No. 17453-98 . Dear Mr. Schottroff: I have been asked to write to you about the mode of failure for pole type structures used to • support wireless phone antennas��equipment, would bed give mI think it would be appropriate to e information to allow you to judge how remote the chances start off by a brief description of the design criteria that is typically used. The pol:s Valmont supplies are designed in accordance with E.I.A./T.I.A.222 Revision F entitled"Structural Standards for Steel Antenna Towers and Antenna Supporting Structures." rstructuresc ." a This is an approved A.N.S.I. standard that has dealt with-the design of lattice type number of years. Revision E is the first version that goes into extensive detail about he edeionognf of pole type structures. The provisions of the standard have,as their foundation, reliability.sThisother nationally known specifications and standards that have a long history history should be of interest to you considering�ctnre�s esigned with conceptsds of thousands(if tspell d out in ons) of sites throughout the United States which have publications like"The Design of Steel Transmission Pole Structures" (published by d ., and"Standard Specifications for Structural Supports for Highway Signs,Luminaries in andtheTraffic Signals" (published by A.A.S.H.T.O.). Many of the concepts used to designpoles two publications are included in the E.I.A./T.I.A.222 Revision F Standard. The L.I.A./T.I.A.222 Revision F requirements dictate a basicsdessign wind d speed s .pThelicy iswind nto use speed-.o be used depends on the location of the site within the the wind speed listed the wind loading in E.1.A./T.I.A.222 as a minimum loading. reoccurrence average in E.I.��./T.I,A.222 has been determined to be thaW�dm ahs that which has tis the average oc ty of a 50 years. This wind is also a"fastest mile"wind mile wind passing a point. For example, a 70 mph average fastest mile wind would take 51 ill seconds to pass a point. This standard"fastest milesp once factor imposed to account for sudden e"wind is customized with factors that apply to the particular installation. There is a 1. 9 gust EXHIBIT D