COMMUNICATION STRUCTURES

Brian W. Smith; BA MS FREng Ceng FICE FISTstructE FASCE

Junio de 2016      Páginas: 352

Código 6923        ISBN/EAN: 9780727734006

CONTENIDO:

"Engineers working in the fields of design, analysis, fabrication and construction of masts and/or towers will accomplish their tasks with confidence by consulting this book”

- Mamoru Kawaguchi, President of IASS

This book combines the accumulated knowledge of structural engineers, scientific researchers, mast and tower owners and antenna experts with experience in the analysis, design, construction and operation of communication structures, into one accessible volume.

It introduces the reader to the basis of design, analysis and construction of lattice towers and guyed masts used for communication purposes (radio, television, mobile phones and radar) and looks at new developments and the effects on the industry. The author focuses on the light and wind sensitive structures that support the aerials that make communication services possible and states that the design and construction of these structures involves significant engineering expertise to ensure that they are safe and reliable, yet cost effective and efficient.

A brief history of tall structures is provided and the various types of structure, dictated by their function and/or location are described. The loading on such structures is described and the methods of calculating their response outlined. Dynamic effects from vortex shedding or galloping are outlined, together with detailed guidance on how to minimise these effects and how to assess fatigue life.

The book provides detailed information on:

• history, design considerations and failures
• meteorological parameters, wind resistance and strength
• aerodynamic stability, fatigue, access and safety
• codes of practice and design standards.

Communication structures is essential for both the established and the new generation of engineers, telecom administrators, contractors, masts and tower fabricators and related professionals.

Brian W. Smith BA MS FREng CEng FICE FIStructE FASCE
Brian Smith is a consultant to the Flint & Neill Partnership having been a partner from 1977 to 1997. He is the Chairman of the BSI Committee on Masts and Towers and a member of the BSI Working Group on Wind Loading and is also a member of the Executive Council of the International Association of Shell and Spatial Structures.

He was Convenor of the project teams for the Eurocodes on Masts and Towers and on Steel Chimneys and was a special advisor to the Highways Agency for the aerodynamic stability of bridges, as well as being a co-author of the British Design Rules. He was Chairman of the Wind Engineering Society from 1999 to 2001 and is responsible for the design and assessment of numerous wind sensitive structures including major bridges, tall towers, masts, footbridges and chimneys.

Contents

• History
• Design considerations
  General
  Choice of site
  Choice of structure
  Economic considerations
  Environmental considerations
  Electronic considerations
  General
  Antenna characteristics
  Low-frequency antennas
  Medium-frequency antenna systems
  VHF and UHF antennas
  Digital audio broadcasting
  Mobile phone antennas
  Effect on existing services of subsequent additional antennas
• Failures of masts and towers
  General
  Icing failures
  Design/detail failures
  Maintenance failures
  Aircraft damage
  Vandal damage
  Lessons to be learned
• Forms of structure
  General
  Timber towers
  Concrete towers
  Lattice steel towers
  Lattice guyed masts
  Tubular guyed masts
  Concrete guyed masts
  Other forms of communication structures
• Meteorological parameters
  General
  Wind
  Wind climate
  Boundary layer
  Serviceability wind speeds
  Atmospheric icing
  General
  Physics and theoretical modelling of ice accretion
  Empirical models to estimate ice loads on Structures
  Earthquakes
  Temperature
  Other meteorological aspects
• Wind resistance
  General
  Symmetrical structures without ancillaries
  Symmetrical structures with limited ancillaries
  General method for structures containing ancillaries
  Linear ancillaries
  Discrete ancillaries
  Cables
  Communications structures
  Measurements on scale model of communications tower
  Discrepancy between wind tunnel tests and full-scale measurements
  Icing
• Response
  General
  Lattice towers
  Guyed masts
  General
  Frequency domain analysis
  Time domain analysis
  Simplified methods
  Summary
• Strength
  Introduction
  Design against buckling — individual members
  General
  Influence of local and torsional buckling
  Angle leg members
  Angle bracing members
  Tubular leg members
  Tubular bracing members
  Solid round members
  Secondary members (‘redundants’)
  Bracing types
  Compound members
  Tension
  Connections
  General
  Flange joints in tubular or solid round leg members
  Guy connections
• Cables
  General
  Types of cables
  Strength of guy ropes
  Rotational characteristics of steel ropes
  Modulus of elasticity
  Prestretching
  Still air tension
  Terminations
  General
  Types of terminations
• Aerodynamic stability
  General
  Vortex shedding
  General
  Background and critical wind speed
  Practical implications
  Damping devices
  Galloping
  General
  Critical wind speed
  Damping devices
• Fatigue
  General
  Lattice towers
  Lattice masts
  Guys
• Foundations
  General
  Foundation types
  Type I: to resist uplift
  Type II: to resist overturning
  Type III: to resist down thrust
  Type IV: guy anchorages
• Codes and standards
  History
  General
  Wind loading
  Ice loading
  Strength
  Other aspects
  Current codes
  Communications structures
  General
  Comparison of current Codes
• Access and safety
  General
  IASS Recommendations for safe access
• Fabrication and erection
  Materials and fabrication
  Steel for towers and mast columns
  Aluminium
  Timber
  Plastics
  Erection
  General
  Erection of lattice towers
  Erection of guyed masts
• Maintenance
  General
  Constraints
  Minimizing maintenance at the design stage
  Manuals
• Seismic response
  General
  Seismicity and earthquake-resistance performance levels
  Prediction of seismic response of structures
  General
  Self-supporting lattice towers
  Monopoles
  Guyed masts
  Antennas and ancillary components
  Geotechnical considerations
• Annex A Codes of Practice and Design Standards
  General
  Comparisons of National Codes
  Scope
  Limit states/reliability classes
  Wind structure
  Wind resistance
  Ice loading
  Displacements/serviceability
  Partial safety factors
  Strength
  Compressive strength
  Tensile strength
  Guy assemblies
  Prestretching
  Terminations
  Initial tensions
  Erection
  Insulators
  Access
• Annex B IASS Working Group Number 4: Masts and Towers
  Brief history
  Role in the future
  The members of the Group
  References
  Index