Design of Steel Tower

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DESIGN OF STEEL TOWERS DESIGN OF STEEL TOWERS

Presented

By,

U. C. T. Warnakulasuriya


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Introduction

Tower configuration

Type of towers

Tower loading

Design of Steel Towers :

Analysis of tower members Design of tower members Bolt Connection

Testing of Towers Design Eample


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T!e tower types used in t!e industry are

"#$ Transmission towers

"#$ % Introduction :

$ Telecommunication and broadcasting

towers

'!y do we need transmission towers

Interconnection of scattered power generatinglocations to t!e national grid and power

distribution re(uires transmission lines#


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$ % Type of Transmission Towers :

Tower types used in t!e transmission line wor) are

Straig!t *ine Towers % *ine de+iation angle is ero

"$$ angle Towers % *ine de+iation angle +aries from

$$ to "$$ degrees

-$$ angle Towers % *ine de+iation angle +aries

from ""$ to -$$ degrees

.$$ angle Towers / *ine de+iation angle +ariesfrom -"$ to .$$ degrees

Terminal towers or dead end towers#


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-#$ % Tower Configuration

Tower configuration depends on t!e followingmain factors,

a# *engt! of insulator assembly


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-#$ % Tower Configuration

b# 0inimum clearance from conductors to t!e

tower steel

c# 0id span clearance under dynamic conductor

be!a+ior

d# 1eometric mean distance between conductors

e# Economic use of tower material


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Tower 2igures


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"#Tower !eig!t considered from ground le+el

0inimum ground clearance

0aimum sag of lowermost conductor

3eig!t and *ocation of 1round 'ires

*engt! of cross arms and !oriontal spacing

between conductors

Tower 2igures


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Tower 2igures


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-# Tower widt! at base and top widt!

Tower base widt! to !eig!t ta)en in t!e range

of to 4#$

4# Bracing pattern used in t!e tower configuration

Tower 2igures

Tower top widt! to base ta)en in t!e range of

"5- to "5-#6


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Tower Bracing Patterns


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Tower Bracing Patterns


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4#$ / Tower *oading

T!e loading applied on transmission line

towers are as follows,

a# 7ertical loads

b# Trans+erse loads

c# *ongitudinal loads


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Vertical Loads

Dead weig!t of tower structure

7ertical *oads due to conductors and ground

wire


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Vertical Loads


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Trans+erse *oads

'ind on conductors and ground wire

Trans+erse component of cable tension in case

of angle tower

'ind on tower body


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*ongitudinal *oads

8nbalance pull due to bro)en wire condition

Pull of conductors and ground wire in case of

dead/end tower#


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6#$ % Analysis of Tower 0embers

A computer software STAAD P9 is used for

t!e analysis of tower members


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.#$ % Design of Tower 0embers

T!e designing of tower members are carried out

according to ASCE "$/;< standard =American

Society of Ci+il Engineers>

Permissible Aial Stress in Tension

Permissible Aial Stress in Compression


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?#$ % Testing of Towers

Transmission line tower remains as one of t!e

few structures in structural engineering w!ic!

is tested full scale to destruction#


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;#$ % Design Eample

Design calculation could be carried out in t!efollowing steps,

Step $" / Collection of design information

Step $& / *oad Calculation

Step $- / Preparation of loading trees

Step $4 / Calculation of wind load on tower aftercompletion of tower geometry

/ 'ind Diagram


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;#$ % Design Eample

Step $6 / Transfer of tower geometry to computerprogram and load application

=wit! computer software>

Step $. / Analysis of tower =wit! computer software>

Step $< / 1rouping of analyse tower member

forces

Step $? / Tower member design

Step $; / Completion of final tower line diagram for

detailing

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Design of Steel Tower