Extracting Size-Dependent Stress–Strain Relationships from FRP-Confined Concrete Cylinders for Varying Diameters and Heights

Abstract

Since most of the available data regarding fiber-reinforced polymer (FRP)-confined columns has been generated from tests on small-scale cylinders, it is important to ensure that the proposed equations are truly representative of the actual behavior of large-scale columns. In this paper, mechanics solutions have been developed to show the influence of specimen size, that is both diameter and height, on the stress–strain relationship of axially loaded FRP-confined concrete cylindrical specimens using shear-friction theory. Two distinct cylinder failure modes have been examined: that of the circumferential wedge that is common in standard cylinders with aspect ratios of 2∶1; and that of the single sliding plane that occurs at higher aspect ratios. It is often quite difficult, if not impossible, due to the capacities of the testing machines, to test large or large-scale FRP-wrapped specimens under pure compression to extract their axial-stress/axial-strain relationships. It is shown in this paper through the mechanics of shear friction, how small-scale FRP-wrapped specimens suitable for compression testing can be designed so that the stress–strain relationship of the large scale member under pure compression can be extracted from those of the small test specimen.