# Experimental Testing of Reinforced Concrete Deep Beams Designed by Strut-And-Tie Method
## 1 Introduction
The amount of added steel fibers in the concrete was 1.5% of the total amount of the concrete mixture. In the paper [8], the appearance of the cracks and the behavior of wall members under the applied load were examined. After the experimental research was completed, it was concluded that the wall members which were made with the addition of steel fibers and a smaller amount of reinforcement, had much fewer cracks. The fibers cannot delay cracking, they can only control cracking, i.e., they can result in more cracks with smaller widths. Experimental testing showed that the directions of the compressed and tensioned Strut-and-Tie elements corresponded to the crack pattern. This supported the conclusion that the method proposed in the paper can be applied in practice. Figure 1: B and D regions. [PERSON], [PERSON], and [PERSON], [9], tested two groups of concrete deep beams, four in each group, differently reinforced and designed by Strut-and-Tie method. The first group of beams includes simply supported deep beams with variable cross-sections and openings and is subjected to a concentrated force at the beam top. The second group of beams are simply supported concrete deep beams with an opening in the lower left part of the beam and is subjected to a concentrated force on the right side of the beam top. The beams were experimentally investigated under stepped loading. The differences in the reinforcement amount, the load-carrying capacity, and the failure pattern of the different specimens were analyzed. Reinforcement efficiency was given according to cost-effectiveness for better assessment of the economic feasibility of the reinforcement design guided by different optimal Strut-and-Tie models. All specimens had an ultimate load-carrying capacity that exceeded the corresponding design load, verifying the conservativeness of the Strut-and-Tie design method. [PERSON], [PERSON], [PERSON], and [PERSON], [10], tested the shear capacity performance for eight deep beams designed by the Strut-and-Tie method according to the provisions of different standards. All of the beams have the same dimensions and different layouts and amount of reinforcement and are made of high-strength concrete. The beams were loaded with two concentrated forces on the beam top. The analyses were conducted to enable a better understanding of the effects of shear span-depth ratio, longitudinal reinforcement ratio, and vertical stirrup ratio, as well as to improve design procedures. It was concluded that the shear span-depth is the most important parameter that controls the behavior and shear capacity of the beams, while the longitudinal reinforcement ratio has no effect on serviceability load, but has a greater impact on the ultimate load. At the same time, vertical stirrup ratio, because of its absence in some of the equations of regulations, has no effect on serviceability and ultimate load, and some of the applied provisions are mostly over-conservative and some have a reasonable degree of accuracy. [PERSON] and [PERSON] [11] have experimentally tested four wall members with openings, using the Strut-and-Tie method to determine the required amount of reinforcement. All wall members had a rectangular shape. The two wall members had only one opening, while the other two had two rectangular openings. The layout of the reinforcement was different for all wall members in accordance with the directions of the struts and ties. The authors concluded that the strength of the elements designed by using the Strut-and-Tie method in relation to the experimentally obtained results is approximately three times higher, which supports the claim related to the conservative nature of the method. The scaled reinforced concrete wall members designed by the Strut-and-Tie method were experimentally tested by [PERSON] and [PERSON] [12]. They have examined four wall members with openings and the same geometry, but with the different reinforcement layouts.