Draft

6.2TheCaseStudy 131

27 Thecablestressesaredeterminedlast,Fig.6.8:

Awire =

D

2

4

=

(3:14)(0:196)

2

4

= 0: 03017 in

2

(6.22-a)

Atotal = (4)cables(26;474)wires/cable(0:03017)in

2

=wire= 3; 200 in

2

(6.22-b)

CentralSpan  =

H

A

=

(220;000)k

(3;200)in

2

= 68: 75 ksi (6.22-c)

SideSpanTower 

ss

tower

=

T

ss

tower

A

=

(262;500)in

2

(3;200)in

2

= 82 ksi (6.22-d)

SideSpanAnchor 

ss

tower

=

T

ss

anchor

A

=

(247;000)in

2

(3;200)in

2

= 77: 2 ksi (6.22-e)

77.2 ksi

73.4 ksi 81.9 ksi

68.75 ksi

Figure6.8:CableStresses

28 If thecableswereto be anchoredto a concreteblock, thevolumeof theblock shouldbe at

leastequaltoV=

(112;000)k(1;000)lbs=k

150 lbs=ft

3 = 747;^000 ft

3

or a cube of approximately91 ft

29 Thedeck, forall practicalpurposescanbe treatedas a continuousbeamsupportedby elastic

springswithstinessK=AL=E(whereLis thelengthof thesupportingcable).Thisis often

idealizedas a beamonelasticfoundations,andtheresultingshearandmoment diagramsfor

thisidealizationareshownin Fig.6.9.