Investigation of mixed-mode fracture of aligned steel fibre reinforced cementitious composites

Mixed-mode fracture experiments were conducted on aligned steel fibre reinforced cementitious composite (ASFRC) and ordinary steel fibre reinforced cementitious composite (SFRC) three-point bending beams. Mixed-mode fracture performances of the ASFRC and SFRC specimens were studied by changing the crack offset distance. The fracture processes of the ASFRC and SFRC specimens were simulated using the extended finite element method. A good agreement was found when the simulation results were compared with the experimental ones. The alignment of steel fibres significantly improved mixed-mode fracture properties. The peak load P-max and crack initiation angle of the ASFRC specimen were obviously greater than those of the SFRC specimen because more steel fibres bridged the crack. Compared to the SFRC, the P-max of the ASFRC increased by 58%, 49% and 38% with the crack offset distances of 0, 50 and 100 mm, respectively. The crack initiation angle of the ASFRC increased by 11% and 17% with the crack offset distances of 50 and 100 mm, respectively. In addition, the influences of the initial crack length to depth ratios a/D and the steel fibre volume fraction V-f on the ASFRC specimens were simulated. The P-max significantly increased with V-f and decreased with a/D