Direct tension test on large concrete specimens - Part I: Tensile strength, fracture properties and size effect

Abstract

The tensile strength and fracture properties of concrete play a vital role in the design of large concrete structures. These properties are evaluated from indirect tests on small-sized specimens. As concrete is known to exhibit a strong size effect, it is important to evaluate these properties from large-sized specimens through a direct tension test. In this research, we perform direct tension tests on large-sized concrete specimens under displacement control. The conditions under which the specimens have to be prepared and tested, and the challenges faced are highlighted. It is seen that the tensile strength is almost half the values that are suggested in major codes of practice. Important elastic and fracture properties under direct tension, including tensile strength, fracture toughness, fracture energy, critical crack mouth opening displacement, critical crack length, and softening law parameters, which find application in non-linear finite element models, are evaluated.