Stringing Chart

Stringing Chart

We have seen in the earlier section that the tension T₂ at the time of erection is given

by,

It is a cubic equation and is very difficult and time consuming to solve.

The use of T₂ is to obtain sag at the time of erection given by,

S₂ = w₂l² / 2T₂

So instead of solving the cubic equation, it is possible to obtain the graph of tension in kg against temperature in °C and the graph of sag in metres against temperature in °C. Such graph is called stringing chart. The stringing chart is shown in the Fig. 4.8.1.

The stringing chart is very useful to find the tension and the sag at any temperature and the loading conditions when these values at any other temperature and the loading conditions are known to us.

In some cases instead of tension T, the stress f is plotted against the temperature as an independent variable. Knowing the area of cross-section 'a', the tension T can be obtained knowing the value of 'f from the stringing chart.

Review Question

1. Write a note on stringing chart and its applications.