CIVIL ENGINEERING FORMULAS

BRIDGE AND SUSPENSION-CABLE FORMULAS 269

wherelspan, or horizontal distance between supports LandRab;h
vertical distance between supports.
The distance from the low point Cto the right support Ris

(10.71)

Supports at Different Levels

The horizontal component of cable tension Hmay be computed from

(10.72)

wherefLvertical distance from CtoL
fRvertical distance from CtoR
fsag of cable measured vertically from chord LR midway between
supports (at xHh/wol)

As indicated in Fig. 10.3(b),

(10.73)

whereyM Hh^2 /2wol^2. The minus sign should be used when low point Cis
between supports. If the vertex of the parabola is not between LandR, the plus
sign should be used.
The vertical components of the reactions at the supports can be computed
from

(10.74)

(10.75)

Tension at any point is

(10.76)

Length of parabolic arc RCis

(10.77)

b^1 (10.78)

6 

wo

H

2

b^3  

LRC

b

2 B

1 

wob

H 

2



H

2 wo

sinh

wob

H

T 2 H^2 wo^2 x^2

Vrwob

wol

2



Hh

l

VLwoa

wol

2



Hh

l

ffL

h

2

yM

H

wol^2

h^2 

fR

h

2

fLfR

wol^2

8 f

b

1

2



Hh

wol