Tension Test of Stress Versus Crack Opening Displacement Using Cylindrical Concrete Specimens
L. R. Lenke and W. H. Gerstle
Appears on pages(s):
concrete; crack opening displacement; direct tension;fracture energy; fracture mechanics; fracture toughness; stressintensity factor; tensile strength
Many laboratory fracture toughness tests have been devised for quasi-brittle materials such as portland cement concrete (PCC). The objective of these tests has typically been to determine linear elastic fracture mechanics parameters such as fracture toughness, Kt,, and fracture energy, Gr. More recently, proposals have been developed to determine the parameters for a variety oftwo-parameter models. For example, the inelastic correction factor method requires parameters KI, and inelastic correction factor p, while the Jenq and Shah two-parameter model requires KI, and CTODc, and the Bazant size effect method requires Grand cr. All of these parameters can be obtained from the stress versus crack opening displacement (o-COD) relationship. The authors describe a test device that is reliable, simple to understand and analyze, relatively inexpensive. and can be used on standard 6-inch diameter by 12-inch concrete cylinders in a universal testing machine (UTM) under load control. This device, called the stiff tensile test (STT) apparatus, is used to obtain the complete versus COD relationship. From this o versus COD relationship, which is fundamental at the meso-scale, can be derived most of the commonly used fracture parameters of concrete.