Back in 2009, I posted a user defined function (UDF) to generate a catenary curve, that could be used together with the Excel Solver to generate a curve of a specified span and sag:

A catenary function

Following a discussion at Eng-Tips (Chain catenary vertical reaction help ) I have updated the spreadsheet to allow different levels at each end, and to plot the full catenary.

The revised spreadsheet can be downloaded from:

Catenary.zip

To use the spreadsheet enter the total horizontal span, the required sag at each end, and an estimate of the span from the left hand support to the low point (“XEnd1”).  Then press the “Adjust A and XEnd1” button.  The solver will adjust the catenary sag and the position of the low point to generate the required sag from each end.  If nothing happens:

1. Try adjusting the XEnd1 value, then click the left hand button, followed by the right.
2. Make sure Solver is enabled.
3. See the previous post