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Re: Cable Tension Force

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Although this equation(shown below) is OK for cables under concentrated
loads, if the distributed
load is constant along the length of the cable (as in the case of a cable
loaded under its own weight) 
the cable will have the shape of a CATENARY. (There is definitely some
value for sag. Also creep shall
be taken into account as well)   These equations are far more
sophisticated and are  functions of hyperbolic 
sinh & cosh.   Any good structural book/hankbook should have these
equations.  However the complete set 
of equations for the catenary is available in the 3rd edition of the
STRUCTURAL STEEL DESIGNER'S 
HANDBOOK by RL Brockenbrough & FS Merrit, McGraw-Hill  Section 15.54
table 15.6.  incluning coordinates,
angles, sag-span ratio, slope, vertical and horizontal components as well
as the cable tension.
These equations are/were adapted from H. Odenhausen "Statical Principles
of the Application of Steel Wire 
Ropes in Structural Engineering".  

Hope this helps.

djk


On Mon, 9 Dec 2002 09:23:34 -0600 "Brian K. Smith"
<smithegr(--nospam--at)bellsouth.net> writes:
> From Roark's Formulas for Stress and Strain, 6th Edition, Table 12, 
> page
> 179:
> 
> For a perfectly flexible cable with pinned ends and unstretchable 
> length L,
> 
> 	y_max = L(3wL/(64EA))^(1/3)
> 
> and
> 
> 	P (tension in cable) = wL^2/(8y_max)
> 
> As you can see, P increases as y_max decreases.
> 
> Brian K. Smith, P.E.
> 
> 
> 
> 
> 
> > -----Original Message-----
> > From: Oshin Tosounian [mailto:oshin(--nospam--at)kcematrix.com]
> > Sent: Sunday, December 08, 2002 11:43 PM
> > To: 'seaint(--nospam--at)seaint.org'
> > Subject: Cable Tension Force
> >
> >
> > Does anyone have the formula to calculate the tension force in a 
> cable to
> > keep it from sagging under its own weight handy?
> > I have a single span condition and a multiple span condition
> > where the cable
> > is free to slide over the intermediate supports. The supports are
> > at varying
> > heights.
> >
> > Thanks in advance.
> >
> > Oshin Tosounian, S.E.
> > Los Angeles, CA
> >
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