PSI - Issue 70

Abutu Simon John Smith et al. / Procedia Structural Integrity 70 (2025) 59–66

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zone reduced with increase in V f in agreement with Bahij (2016) report that ordinary UHPFRC beams with higher V f have less number of cracks at failure stage. Furthermore, Figure 5 showed that reduction in a /d from 2.82 to 2.08 led to increase in the number of cracks (from one to six) formed within the flexural zone but had no effect on the number of cracks formed within the shear zone. The number of cracks that develop on a UHPFRC-CA beam undergoing shear test has a significant effect on the shear capacity of the beam in that, the development of large number of cracks is the reaction of the beam to the absorption of fracture energy, in order to release the energy. The release of this energy helps improve the ductility and shear capacity of the concerned beam.

10 12

BS/2/2.82 BH/2/2.82 BS/3/2.82 BS/2/2.08

0 2 4 6 8

Number of cracks

Flexural zone Shear zone

Fig. 5. Number of cracks formed within the beams’ shear and flexural zones

3.3. Crack Distance from the Nearest Support Measuring tape was employed for measuring the position of the flexural crack and diagonal crack in the UHPFRC-CA beam; and the horizontal distance drawn through the center of the longitudinal tensile reinforcement was used as the reference line. Figure 6 showed that the flexural crack for BS/2/2.82, BH/2/2.82, BS/3/2.82 and, BS/2/2.08 was formed at 515mm, 473mm, 476mm and 495mm distance respectively from the closest support of each beam. Figure 6 also revealed that the diagonal crack for BS/2/2.82, BH/2/2.82, BS/3/2.82 and, BS/2/2.08 was formed at 240mm, 245mm, 317mm and 108mm distance respectively from each beam’s closest support. More analysis of Figure 6 have shown that beams made with hooked-end steel fiber have their main flexural crack formed about 8% closer to the nearest support than those made with straight steel fiber; while hooked-end steel fiber caused the diagonal crack to be 2% farther from the nearest support.

BS/2/2.82 BH/2/2.82 BS/3/2.82 BS/2/2.08

0 100 200 300 400 500 600

support (mm)

Distance from the nearest

Diagonal crack

Flexural crack

Fig. 6. Crack distance from the nearest support