This paper considers three methods for calculating the un-stretched length of a cable with significant self weight when the final static equilibrium conditions are known. The first method uses an average line tension and Hooke’s Law to estimate the un-stretched length. The second method uses a Lagrangian co-ordinate and Hooke’s Law to form an exact equation for the un-stretched length, given the assumption that the cable is linear elastic and the change in length is due to elastic stretch. The third method uses a Lagrangian coordinate; however, construction stretch is included in addition to elastic stretch. The results of this paper indicate the average tension is a suitable surrogate for a tension function that is a function of position when considering elongation to be the result of elastic stretch. When construction stretch is considered, the average tension method also performed well for cables with tensions less than one-third the minimum breaking strength.
