Issue 78

M. Adel et.al, Frattura ed Integrità Strutturale, 78 (2026) 168-185; DOI: 10.3221/IGF-ESIS.78.10

1) MC-RC-FRC Beam

2) MC-NC Beam

3) TTC-RC-FRC Beam

4) MC-FRC Beam

5)

b) Second group (a/d=0.25) and third group (a/d=0.5) Figure 1: Schemes of experimental specimens.

Preparation of matrix crack To create matrix cracks on the tensile side of the cracked specimens, a 2 mm thick foam plate was utilized. This plate was strategically placed through grooves cut into both lateral surfaces at the midpoint of the steel casting mold. This setup enabled the steel fibers to intersect and span across the foam interface. It was assumed that the steel fibers were evenly distributed within the area defined by the foam strip, as illustrated in Figs. 2(A) and 2(B). The procedure for determining the number of fibers that passed through the foam plate involved the following steps: First, the total mass of the fibers was calculated by measuring the volume of a concrete strip with a length corresponding to the individual fiber length, a width matching the beam’s breadth, and a height equal to the crack dimension. The mass of the fibers in the strip (Ws) was then computed as one percent of the derived volume. The proportion of steel fibers allowed to cross the foam interface was determined based on theoretical assumptions from this research. Previous studies have indicated orientation factors ranging from 40% to 60% [19,20]. Therefore, a midpoint value of 50% was chosen for this analysis, as it lies within the identified

173