I am trying to create an interaction diagram for a circular concrete column. This is based off of an Excel spreadsheet that is currently being used and I am trying to convert that into a Mathcad spreadsheet. in the Excel spreadsheet the vertical load strenght and moment strength were found using the what-if function. The Excel spreadsheet solves for the total vertical load strength by adding the vertical load strength of the concrete (Pconc) and the vertical load strength of the steel (Pst) as is the same for the total moment Mn = Mconc + Mst. for Pst and Mst I am using the Range of Variable Summation to sum the values in a Range (obviously). The summation comes up with the right value, but I need this to be converted back into a range as it is dependent on the value c. That is pretty confusing so I will give an example. c is a range of values. the first value of c is 0 which gives me a sum(Mst) = 8.05 * 15^-15 but I need the sum(Mst) to change as c changes because It needs to be added to Mconc to get the right Mn value. I will attach the spreadsheet so you can see what is going on, but I was just wondering if it was possible to make the range variable summation function change with respect to cj? I have also attached the excel file. you will need to unprotect the file and unhide rows 21-62.
