Title: Flexural Strength of Prestressed Concrete Sections by Programmable Calculator
Date: January-February, 1979
Volume: 24
Issue: 1
Page number: 32-54
Author(s): Alan H. Mattock
https://doi.org/10.15554/pcij.01011979.32.54

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Abstract

It has always been recognized that the approximate Eq. (18-3) in ACI 318-77 for the stress in bonded prestressing steel at flexural ultimate, f_ps was in general conservative. A more precise value for f_ps  and hence for the flexural strength, can be obtained by solving the equations of equilibrium of forces and of compatibility of strains across the section, making use of the actual stress-strain relationship for the prestressing steel. Until the advent of the computer and the programmable calculator, this was a time-consuming process and hence was little used. In a 1977 paper, Naaman2 discussed the more  precise approach. He showed how more accurate values of flexural strength could readily be obtained using a computer to solve the equations of equilibrium and compatibility, if the stress-strain curve  for the prestressing steel were expressed algebraically. Since the time of Naaman's studies, there has been an explosion in the availability and the capabilities of  small programmable electronic   calculators. These machines now make it feasible and economic for any engineer to use the more precise method of calculation for flexural strength, with consequent economic advantages.