1、 International Telecommunication Union ITU-T L.89TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU (02/2012) SERIES L: CONSTRUCTION, INSTALLATION AND PROTECTION OF CABLES AND OTHER ELEMENTS OF OUTSIDE PLANT Design of suspension wires, telecommunication poles and guy-lines for optical access networks R
2、ecommendation ITU-T L.89 Rec. ITU-T L.89 (02/2012) i Recommendation ITU-T L.89 Design of suspension wires, telecommunication poles and guy-lines for optical access networks Summary Recommendation ITU-T L.89 describes the general requirements and a design guide for suspension wires, telecommunication
3、 poles and guy-lines that support aerial cables for optical access networks. This Recommendation also describes loads applied to the infrastructures. History Edition Recommendation Approval Study Group 1.0 ITU-T L.89 2012-02-13 15 Keywords Aerial infrastructure, guy-line, ice loading, suspension wir
4、e, suspension wire tension, telecommunication pole, vertical load, wind loading. ii Rec. ITU-T L.89 (02/2012) FOREWORD The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications, information and communication technologies (ICTs). The I
5、TU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis. The World Telecommunication Standardi
6、zation Assembly (WTSA), which meets every four years, establishes the topics for study by the ITU-T study groups which, in turn, produce Recommendations on these topics. The approval of ITU-T Recommendations is covered by the procedure laid down in WTSA Resolution 1. In some areas of information tec
7、hnology which fall within ITU-Ts purview, the necessary standards are prepared on a collaborative basis with ISO and IEC. NOTE In this Recommendation, the expression “Administration“ is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. Compli
8、ance with this Recommendation is voluntary. However, the Recommendation may contain certain mandatory provisions (to ensure, e.g., interoperability or applicability) and compliance with the Recommendation is achieved when all of these mandatory provisions are met. The words “shall“ or some other obl
9、igatory language such as “must“ and the negative equivalents are used to express requirements. The use of such words does not suggest that compliance with the Recommendation is required of any party. INTELLECTUAL PROPERTY RIGHTS ITU draws attention to the possibility that the practice or implementat
10、ion of this Recommendation may involve the use of a claimed Intellectual Property Right. ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process. As o
11、f the date of approval of this Recommendation, ITU had not received notice of intellectual property, protected by patents, which may be required to implement this Recommendation. However, implementers are cautioned that this may not represent the latest information and are therefore strongly urged t
12、o consult the TSB patent database at http:/www.itu.int/ITU-T/ipr/. ITU 2012 All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU. Rec. ITU-T L.89 (02/2012) iii Table of Contents Page 1 Scope 1 2 References. 1 3 Defin
13、itions 1 3.1 Term defined elsewhere . 1 3.2 Terms defined in this Recommendation . 1 4 Abbreviations and acronyms 2 5 Conventions 2 6 Configuration of aerial infrastructure . 2 6.1 Aerial communication infrastructure on shared poles 2 7 General requirements for aerial infrastructure design 2 7.1 Cla
14、rification of optical fibre cables 2 7.2 Classification of site conditions 2 7.3 Safety and economic considerations 3 7.4 Management of ground height and offset distance . 3 7.5 Loads applied to aerial infrastructure . 3 8 Design of suspension wires 5 8.1 Materials . 5 8.2 Selection of suspension wi
15、re type 5 8.3 Sag 5 9 Design of telecommunication poles . 6 9.1 Materials . 6 9.2 Embedded depth . 6 9.3 Pole length 6 9.4 Classification 6 10 Design of guy-lines . 7 10.1 Configuration 7 10.2 Installation angle of upper guy-lines 7 10.3 Classification of upper guy-lines 7 10.4 Classification of guy
16、 anchors . 7 Appendix I Relationship between sag and the length of suspension wire 9 I.1 Introduction 9 I.2 Calculation of required suspension wire length . 9 I.3 Calculation considering the change of temperature and load applied to the wire . 9 iv Rec. ITU-T L.89 (02/2012) Introduction Suspension w
17、ires, telecommunication poles and guy-lines that support aerial optical fibre cables are important facilities for providing broadband services. An appropriate design is needed to maintain the reliability of these facilities and services. Moreover, they are big facilities installed at a high position
18、 and so they should be managed in a way that ensures sufficient safety. To realize these requirements, a design is needed that carefully considers facility strength. Rec. ITU-T L.89 (02/2012) 1 Recommendation ITU-T L.89 Design of suspension wires, telecommunication poles and guy-lines for optical a
19、ccess networks 1 Scope This Recommendation deals mainly with fundamental requirements for designing suspension wires, telecommunication poles and guy-lines supporting aerial optical cables. In this Recommendation aerial infrastructures mean suspension wires, telecommunication poles and guy-lines. Th
20、e intent of such a plant is to support outdoor cables that will be attached by lashings, clips, or similar mechanisms. Note that self-supporting cables such as the one shown in Figure 8, ADSS, or others, while not specifically addressed by this Recommendation, have the same issues applicable to thei
21、r installation. 2 References The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the editions indicated were valid. All Recommendations and other references are su
22、bject to revision; users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references listed below. A list of the currently valid ITU-T Recommendations is regularly published. The reference to a documen
23、t within this Recommendation does not give it, as a stand-alone document, the status of a Recommendation. ITU-T L.26 Recommendation ITU-T L.26 (2002), Optical fibre cables for aerial application. ITU-T L.58 Recommendation ITU-T L.58 (2004), Optical fibre cables: Special needs for access network. ITU
24、T L.87 Recommendation ITU-T L.87 (2010), Optical fibre cables for drop applications. ITU-T L.88 Recommendation ITU-T L.88 (2010), Management of poles carrying overhead telecommunication lines. 3 Definitions 3.1 Term defined elsewhere None. 3.2 Terms defined in this Recommendation This Recommendatio
25、n defines the following terms: 3.2.1 guy-line: A wire installed to prevent poles collapsing as a result of tension imbalances that occur during or after cable installation. One end of the guy-line is fixed to the pole and the other end is fixed to the ground by a guy anchor. 3.2.2 messenger: An alte
26、rnative term for suspension wire. 3.2.3 suspension wire: Wire that is installed in advance between telecommunication poles from which aerial optical cables are suspended. It supports a tension applying to non-self-supporting aerial optical cables. 2 Rec. ITU-T L.89 (02/2012) 4 Abbreviations and acro
27、nyms This Recommendation uses the following abbreviations and acronyms: ADSS All-Dielectric Self-Supporting CAPEX Capital Expenditure 5 Conventions None. 6 Configuration of aerial infrastructure The aerial infrastructure consists of a suspension wire (messenger), a telecommunication pole and a guy-l
28、ine as shown in Figure 1, and supports the optical fibre cables for aerial applications described in ITU-T L.26, ITU-T L.58 and ITU-T L.87. L.89(12)_F01Suspension wire(Messenger)Guy-lineTelecommunication poleFigure 1 Aerial infrastructure 6.1 Aerial communication infrastructure on shared poles The a
29、erial optical cable infrastructure may also be co-located on poles carrying power cables. While such installations follow the intent of this Recommendation, the effects of the loading, spacing, and guy-line construction for the power cables must also be considered. Local regulations will also affect
30、 the spacing and sag of communication plants. 7 General requirements for aerial infrastructure design 7.1 Clarification of optical fibre cables The main function of the aerial infrastructure is to support optical fibre cables. The type and number of optical fibre cables that are supported are decide
31、d based on demand forecasts and future plans for networks, and so the design of an aerial infrastructure strongly depends on the optical fibre cables supported. Therefore, telecommunication companies shall know what kind of optical fibre cables will be installed; taking account of their future plans
32、 7.2 Classification of site conditions Ideally, aerial infrastructure is designed in accordance with the conditions of each individual site. However, designing on such an individual basis raises capital expenditure (CAPEX). Therefore, a certain level of design standardization is necessary to simpli
33、fy the design and construction process, in order to reduce CAPEX. As one example of this standardization, site conditions may be classified based on wind loading, ice loading and/or soil property. Telecommunication companies should carefully investigate the site conditions so that the site can be co
34、rrectly classified. Rec. ITU-T L.89 (02/2012) 3 7.3 Safety and economic considerations Aerial infrastructure consists of large facilities that are installed high above the ground. So, it is recommended that telecommunication companies carefully consider safety and avoid any accidental destruction to
35、 aerial infrastructure by employing a design with sufficient strength and protection against lightning. Note that telecommunication companies should also consider reducing CAPEX while maintaining safety. 7.4 Management of ground height and offset distance It is recommended that aerial infrastructure
36、 (including cables shown in ITU-T L.26, ITU-T L.58 and ITU-T L.87) has sufficient ground height to prevent any component from being a traffic barrier and to eliminate risks to people and other constructions. The ground height shall be evaluated in wind-free conditions. An offset distance that is as
37、great as possible should be established between optical fibre cables and electrical cables to achieve safety and workability. In general, ground height and offset distances are defined by regulations, and so telecommunication companies shall follow these regulations when designing aerial infrastruct
38、ure. L.89(12)_F02Required ground heightFigure 2 Ground height 7.5 Loads applied to aerial infrastructure Aerial infrastructure should be designed in accordance with the loads applied to them to maintain their reliability and safety. In particular, telecommunication companies should carefully conside
39、r wind loading, suspension wire tension and vertical load, as shown in Figure 3. These loads must include the weight of the cable(s) which are expected to be supported by the suspension wire (see clause 7.1). 7.5.1 Wind loading The wind load peaks when the wind blows at right angles to an aerial inf
40、rastructure. At that time, the wind load TwN can be obtained by the following equation. SVCTwDw221= (7-1) where , CD, Vwand S are the air density, the drag coefficient of the infrastructure determined by wind tunnel testing, the wind velocity and the profile area of the cable and the suspension wire
41、 respectively. Note that ice accretion to the cable and suspension wire may increase in their profile area. 4 Rec. ITU-T L.89 (02/2012) 7.5.2 Suspension wire tension The suspension wire tension is the load supported by suspension wire. The suspension wire tension T N can be obtained with the follow
42、ing equation. dWLT82= (7-2) where L is a span length. d is a sag and has an inverse ratio to T. In terms of the ground height, a smaller sag is desirable, but this increases suspension wire tension as shown in Figure 4, and so an aerial infrastructure with greater mechanical strength is required. Th
43、erefore, telecommunication companies should design the sag and the suspension wire tension so that they are in balance. As shown in Figure 5, W is the load imposed by the sum of the wind load and the cable weight. Note that the resultant load W N/m should be defined as the value per unit length. So,
44、 it is given by: 22+=DTwWw(7-3) where w and D are an aggregate of cable and suspension wire weights per unit length and aggregate of cable and wire diameters, respectively. Note that the suspension wire tension reaches its maximum value at its minimum temperature because metal contracts as the tempe
45、rature falls. Ice loading should be included in cable weight. Ice loading guidelines are generally established by local, regional, or national authorities. Different ice density values for radial and rime ice may be used depending upon local conditions. 7.5.3 Vertical load This is load applied to a
46、telecommunication pole vertically. Typical vertical loads are as follows: weight of telecommunication pole; weight of snow and ice adhering to telecommunication pole; vertical component of guy-line tension; weight of workers and tools. It is recommended for telecommunication companies to consider ma
47、ximum vertical load when designing telecommunication poles. L.89(12)_F03Vertical loadSuspension wire tensionWind loadFigure 3 Wind load, suspension wire tension and vertical load Rec. ITU-T L.89 (02/2012) 5 L.89(12)_F04LLddT TFigure 4 Relationship between suspension wire tension and sag TDwL.89(12)_
48、F05WindW: Resultant loadwFigure 5 Resultant load applied to a suspension wire 8 Design of suspension wires 8.1 Materials It is recommended that stranded steel wire be used as suspension wire. Anticorrosive material, e.g., aluminium-coated steel or zinc-coated steel, should be used for the suspension
49、 wire in areas with a corrosion risk. Typical corrosion risk areas are as follows: Near the coast; corrosion by salt breeze. Industrial and mining areas; corrosion by sulphur dioxide gas. Hot springs (warm water found in a volcanic location) and volcanic areas; corrosion by hydrogen sulphide. 8.2 Selection of suspension wire type It is recommended for telecommunication companies to select the suspension wire in accordance with the specifications of the aerial cables that it supports. When a future expansion plan
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