## 2 Literature Review
### The General Behavior of SFRC Beams
As reported by [PERSON] and [PERSON] [24], the dowel action in the slender SFRC beams varied between 10 to 35% of the total shear capacity as the height of beam varied between 305 to 1220 mm, and the shear span-to-effective depth ratio of tested beams ranged from 3.45 to 3.6. Therefore, according to research conducted by [PERSON] and [PERSON] [23] and [PERSON] and [PERSON] [24], the dowel action contributed to the shear strength of SFRC beams. On the other hand, [PERSON] et al. [25] reported that the shear contribution of dowel action was ignored according to the test results of 24 beams (4 plain concrete beams and 20 SFRC beams). The failure mode for plain concrete beams was diagonal tension, while 18 SFRC beams failed due to shear tension. Figure 2 shows the relationship between the normalized shear strength and the longitudinal tensile reinforcement ratio for different shear-span-to-effective depth ratios. It can be seen that the longitudinal tensile reinforcement ratio improves the SFRC shear strength, regardless of the contribution of dowel action. Figure 1: The relationship between normalized shear stress and shear span-to-effective depth ratio [11]. Figure 2: Relationships between normalized shear stress and longitudinal tensile reinforcement ratio [11; 13]. The concrete compressive stress is one of the important parameters for ultimate shear strength of the SFRC beam. It can be observed from research conducted by [PERSON] et al. [17] that when the concrete compressive strengths were increased up to 100%, while other parameters remained the same, the improvements of ultimate shear strength were 26%, 21%, and 20% for beams with shear span-to-effective depth ratio of 2, 3, and 4, respectively. In regard to the contribution of aggregate size to shear capacity, greater aggregate size in the SFRC beam could enhance the shear resistance of the beam due to increased aggregate interlock [21]. To be on the safe side, most researchers selected aggregate with maximum size of 9.5 mm accordingly [21]. [PERSON] and [PERSON] [24] measured the shear resistance from aggregate interlock at any point along crack length with a crack width exceeding 0.2 mm. It was reported that the contribution of aggregate interlock to shear resistance ranged from 0 to 5% [24]. Also, it was reported that the aggregate interlock in the SFRC beams had a minor contribution at the point where the beams reached their peak strength. The last two important parameters are the fiber volume fraction and the bond strength of the fiber-matrix interface. The effect of fiber volume fraction on shear strength also depends on fiber diameter and fiber length [21]. The table in Appendix A presents the shear stresses of SFRC beams with different fiber volume fraction and aspect ratio, where those results are part of the experimental results collected in this study. It can be seen that when the fiber volume fraction and the steel fiber aspect ratio are varied, while other parameters remain the same, there is almost no difference in the shear stresses. For example, it can be found from the test results conducted by [PERSON] et al. [25], in which 4 SFRC beams contained 2 different steel fiber aspect ratios and fiber volume fractions, while other parameters remained the same. The specimens B18-3c, B18-3d, B18-5a, and B18-5b had similar ultimate shear stress. This is because specimens B18-3c, B18-3d, B18-5a, and B18-5b had a similar reinforcing index for steel fiber, RI, in which RI is a multiplication of the steel fiber aspect ratio and the fiber volume fraction. Improving the fiber volume fraction may improve shear strength significantly, if the fiber volume fraction is the only parameter improved, while other parameters, including steel fiber aspect ratio, are kept to remain the same [11; 26]. The bond strength of the fiber-matrix interface has usually been neglected. [PERSON] et al. [27] set the bond strength between steel fibers and concrete matrix at 4.15 MPa. [PERSON] et al. [2] and [PERSON] et al.