Design of SFRC structural elements: post-cracking tensile strength measurement

Utilisation of steel fibre reinforced concrete (SFRC) for designing structural members requires knowledge of the post-cracking tensile response. This paper reviews the experimental characterisation tests and subsequent analysis commonly used for determining the post-cracking tensile properties of SFRC. The experimental program supporting this investigation comprised five different SFRC mixes with fibre volumes ranging from 0.75 to 1.25% used to fabricate a set of characterisation specimens for uniaxial tension tests, notched beam tests and round panel tests carried out in parallel with an extensive experimental program on large scale beams. Characterisation test results allowed a comparison between direct stress–crack opening measurements and the stress–crack openings retrieved from the inverse analysis of bending tests. Discrepancies in post-cracking tensile results obtained with the three types of tests are analyzed and related mainly to test configurations, the presence of a predefined crack, support conditions, fibre orientation, and cracked surface size. Results obtained using material characterisations are then applied to the reproduction of the structural behaviour of large scale beams, documented in a companion paper.