Shrinkage and creep response of slender reinforced concrete columns under moment gradient: theory and test results

Abstract

Slender structural members experience geometric non-linearities under eccentric axial compression. Reinforced concrete columns under sustained compression also experience material non-linearities owing to the viscoelastic effects attributable to shrinkage and creep. This paper presents a technique based on expanding the deflected shape of an eccentrically loaded column as a Fourier series to study the response of rectangular reinforced concrete columns under a sustained compressive force applied at each end with unequal eccentricities. The technique allows for the coupling of geometric non-linearity and viscoelasticity, and includes cracking of the concrete. Test results are reported on five slender columns of square cross-section (with L/D ratios of 33·3) under sustained axial compression applied eccentrically, and it is shown that the numerical scheme predicts the experimental results with good accuracy. These test results also add to the smallish pool of accurately conducted experiments on slender columns under sustained loading, and especially provide benchmark test data for unequal end eccentric loading for which test results seem somewhat scarce.