I’ve written this spreadsheet to calculate the specifications for the electrical power supplies to heat the strands of stay cables of the Queensferry Crossing or of other bridges prone to icing with similar cables of an arbitrary number of strands up to 109 strands.
This is a screenshot – click to view a high-resolution image.
Download QFC Electrically-heated Cables. It’s an Excel .xlsx file but it was developed in Google Sheets (for free!). I don’t have Excel on my computer so it has never been tested in Excel. If it doesn’t work on Excel then try uploading it to Google sheets. That should work but any problems let me know
and if necessary I can let you share my Google sheets version with viewer access which I can authorise to any Gmail account and then you can copy it directly into your Google sheets file space.
Select a strands sheet with the closest number of strands to the cable you want to calculate for, choosing between 45, 55, 73, 91 or 109 strands. Best to duplicate the sheet for back-ups.
The strands arrangement is represented by coloured cells where the cell formula calculates that strand’s heating capacity.
To re-arrange and / or change the number of strands, first drag off the strand circles overlay image then add strands by selecting an existing strand cell, Edit Copy (ctrl-C) then select another coloured cell for the new strand and Edit – Paste special – Paste formula only. To remove a strand just delete the formula from its coloured cell.
To use the Strands calculator spreadsheet with data for another bridge, you will have to edit or create a new “Cable Data” sheet with the new data and modify the strands calculator sheets’ (hidden) cell X61 so that it fetches the cable data from the new sheet with the appropriate table range.