Mechanical properties of SFRC at high temperatures

Abstract

Steel fibre reinforced concrete (SFRC) is more often considered as a profitable replacement of diffused reinforcement, like welded steel mesh, especially for thin cross section. In this case, fire becomes a crucial condition for design. An experimental investigation was carried out in order to evaluate the benefits in fire resistance of steel fibre when structural elements are bent (di Prisco et al. 2003). First of all, four point bending tests were carried out on notched 600 mm long beams with a 150×150 mm cross section and a notch/depth ratio equal to 0.3. Once carried out the bending tests, two cylinder specimens were cored from each beam: one was tested in uniaxial compression while the other, once notched, was tested in direct tension.

The average uniaxial tension and compression test results are first used as constitutive relationships to reproduce the bending tests, neglecting notch effects.

A brief description of the experimental set-up used in direct tension is instrumental to present and discuss the eccentric tension imposed in the specimens by an active control designed to keep the press platens fixed. The measured bending moment was adopted to quantify the heterogeneity degree of SFRC specimens, before and after cracking.