Title: Comparison of Measured and Calculated Stiffnesses For Beams Reinforced in Tension Only

Author(s): Bill G. Eppes

Publication: Journal Proceedings

Volume: 56

Issue: 10

Appears on pages(s): 313-326

Keywords: none

DOI: 10.14359/8099

Date: 10/1/1959

Abstract:
In any study of mechanics of indeterminate structures stiffness plays an important role in analysis. Analysis leads to the determination of the redundant quantities, which in turn lead to the determination of the critical bending moments and shears. The factor EI, which is a measure of stiffness, is necessary for determining deflec- tions of any elastic structure, be it statically determinate or statically indeterminate. This paper is a presentation of the findings of an experi- mental measurement of stiffness (EI) for reinforced concrete beams. Measured values of stiffness are compared with the calculated values for nine beams. It was found in this study that the measured values of stiffness decrease with increased bending moment, show- ing first a large value for stiffness for the lower values of moment and then a rather sudden transition to a lower value of stiffness for larger values of moment. The larger measured values compare reasonably well with the calcu- lated gross section of a reinforced concrete beam with transformed area of steel and the lower values compare fairly well with the calculated net section of the reinforced concrete beam with transformed area of steel included.