Elastic Analysis of Reinforced and Prestressed Sections
The spreadsheet presented in the previous post in this series uses the basic equation given below to find the location of the neutral axis:
For a cross section with any applied axial load at eccentricity e, measured from the compression face, and depth of the neutral axis X below the compression face:
INA = QNA(X + e)
Where QNA and INA are the first and second moments of area about the neutral axis.
To illustrate this relationship the value of INA has been plotted for a range of neutral axis positions for a typical precast bridge beam, shown below, and compared with the value QNA(X + e) for 5 different values of e.
Download Elastic Analysis of Reinforced and Prestressed Sections Spreadsheet
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