Dear members I need these papers:
Transmission tower development in the UK
Authors:
C. Lomas
Abstract
This paper looks back on the development of the lattice steel tower and the use of lattice towers on overhead transmission lines in the UK over the past sixty years. It reviews the current regulations and the National Grid Company's approach to alternative tower types.
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A review of dynamic aspects of transmission line design
Authors:
B.W. Smith
Abstract
A review of current practice in the United Kingdom is provided regarding the dynamic problems associated with conductors, including galloping, wake induced vibrations and vortex excitation. The response of transmission line towers is discussed and the parameters which are of most importance highlighted. The background to the treatment adopted in the United Kingdom Code of Practice is described, including the development of the parameter to assess the dynamic sensitivity of towers. This parameter is used to judge whether simplified static procedures may be safely used in design.
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Probabilistic wind loadings on transmission line structures in India
Authors:
M.J. Alam, A.R. Santhakumar
Abstract:
An evaluation of probabilistic wind loadings on transmission line structures in India according to the recommendations of International Electrotechnical Commission/Technical Committee 11 (IEC/TC 11) is presented in order to promote international unification. The wind loads thus obtained are compared with relevant Indian, German and other European specifications. Typical towers are then analysed for these loads considering critical load cases using the developed software, TLEXPERT. There are considerable differences in certain details when Indian Standard (IS): 802–1977, Indian Standard (IS): 802–1989 (proposed) and German Standard DIN VDE 0210 are compared. As a whole, however, the design according to IS and VDE lies within the bandwidth which is outlined by the IEC recommendations. The example discussed illustrates the difficulties encountered during the practical application of probabilistic design and provides a pointer towards desirable improvements.
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Full Scale Testing of Transmission and Telecommunication Towers Using Numerical Simulation Techniques
Authors:
S. Kitipornchai, F.G.A. Al-Bermani
Publisher Summary
This chapter describes a compact and practical nonlinear analytical method for simulating the global structural response of transmission and telecommunication towers. The tower is modeled as an assembly of beam column elements. Linear, geometric, and deformation stiffness matrices are used to describe the behavior of a general thin-walled beam-column element in an updated Lagrangian framework. The formulation reduces greatly the number of elements required for accurate modeling of the nonlinear structural response. A lumped plasticity approach coupled with the concept of the yield surface in force space is adopted for modeling material nonlinearity. A formex configuration formulation of the towers is used for automatic generation of data necessary for the analysis. The proposed numerical simulation technique is used to investigate the ultimate structural behavior of several latticed and guyed transmission and telecommunication towers under different loading conditions. The technique has now been accepted by many power supply authorities as a tool for replacing the current practice of full-scale tower testing.
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Chapter 15 – Substation and Overhead Line Foundations
Authors:
Dr C.R. Bayliss, CEng FIET, B.J. Hardy, CEng FIET
Publisher Summary
The design of overhead line tower or substation gantry structure foundations must be such as to safely sustain and transmit to the ground the combined dead load, imposed load, and wind load in such a manner as not to cause any settlement or movement, which would impair the stability of the structure or cause damage. The settlement is a result of the transfer of load from the structure to the soil layers. Essentially settlement must be minimized to an acceptable level for the design life of the structure and adequate factors of safety applied to ensure this. Foundation design requires information on the properties of the soil and in particular its compressibility, moisture content, plasticity characteristics, friction between soil particles, and for fine soils, its undrained shear strength. This chapter describes typical soil investigations and foundation design. Such design is the responsibility of the civil engineer. The details described in this chapter are intended to give the transmission and distribution electrical engineer an appreciation of the factors involved.
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Chapter 17 – Structures, Towers and Poles
Authors:
Dr C.R. Bayliss, CEng FIET, B.J. Hardy, CEng FIET
Publisher Summary
This chapter describes the basic input data required and terminology used for the design of substation steel structures, overhead line towers, and poles. The industry is currently revising its approach to the general concepts of tower design. The loadings and related strengths required for overhead line design have normally been determined by Statutory Instruments, the client's specifications or the consulting engineer's specifications. The international standards applicable are listed and their applications are explained. The newer ENs offer the alternatives of a probabilistic approach to design or an empirical approach based on national/local experience. Such issues are the responsibility of the specialist structural engineer. Therefore the chapter provides very basic examples to allow the electrical engineers to understand the fundamental principles and terminology involved rather than the specific methodologies.
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Chapter 19 – Testing and Commissioning
Authors:
Dr C.R. Bayliss, CEng FIET, B.J. Hardy, CEng FIET
Summary
This chapter describes the testing and commissioning necessary before power transmission and distribution equipment is ready for service. Consideration is given under the following headings: Quality Assurance, Works Inspection and Testing, Site Inspection and Testing, Testing and Commissioning Methods.
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Reliability analysis of Australian communication lattice towers
Authors:
L. Pham, J.D. Holmes, J. Yang
Abstract
An Australian Standard (AS 3995) has been published for the design of communication lattice towers and masts in limit states format. As a background study for this project, a reliability analysis has been carried out to calibrate the design process for lattice towers proposed in the new Standard to the current Australian Telecom design practice. Probabilistic models have been established for (a) the wind loads on towers, and (b) the strengths of the major components of the towers. The results indicate that the reliability indices for Australian communication towers are about the same as those for American transmission line towers, and are lower than those for Australian steel building components designed to AS 4100. The implications of the calibration results on the assessment of existing towers are also discussed.
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Dynamic behaviour of transmission towers: field measurements
Authors:
Jens Jacob Jensen;Gunnar Folkestad
Abstract
Comparison of results of measurements with analytical work is of high value in evaluation of the design specifications of tower structures. The present study gives examples of the general dynamic behaviour, and information about design parameters to be used in analysis of such structures. Inspections and control systems to discover structural irregularities and evaluations of fatigue damage have been demonstrated.
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Geometric Nonlinear Analysis of Transmission Tower with Continuous Legs
Authors:
Yan Hui1, Liu Yanjun2, Zhao Diansheng3
Publisher Summary
Transmission tower is a highly indeterminate space structure. It is generally constructed of asymmetric thin-walled angles eccentrically connected at joints, and is widely regarded as one of the forms of lattice structures, which is most difficult to analyze. In the current analysis and design, a tower is modeled as space truss, it's all members are assumed to be axially loaded and pin-connected at joints. In practice, such assumption can hardly be met in most actual transmission towers. In the conventional approach to the design of transmission towers, members are assumed to be hinged at joints. In practice, however, this assumption is rarely realized because of manufactural difficulties. Results from full-scale tests show that the secondary stress may be as significant as primary stress. A method for the geometric nonlinear analysis of transmission towers under static load conditions is developed, in this method legs are treated as beam-columns and the other members as space truss members. Based on the stiffness matrix of an element, an updated Lagrangian formulation with the numerical arc-length technique is employed to trace the nonlinear load-deflection path up to the maximum load. The proposed method is used to analyze a practical transmission tower, and some useful conclusions are drawn.
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thanks and regards
apocalipse