## 2 Experimental Program
### Methods
#### 2.2.3 Testing Details  
Material Properties  
The compressive strength of the UHPC samples was determined using a universal compression testing machine [Instron (Norwood, MA, USA), with a capacity of 3000 kN, Figure 3a]. This test was accomplished in compliance with ASTM C109 specifications of a constant loading rate of 0.2 MPa/s. The test control unit is shown in Figure 3b. It is worth noting that previous studies on the compressive behavior of UHPC using the ASTM C109 standard and cubic specimens have shown closely comparable results to the response obtained by the ASTM C39 by employing cylindrical specimens. Accordingly, the cubic concrete samples that do not require preparation of their ends have the potential to effectively substitute for the cylindrical ones [40]. The flexural test (Figure 3c,d) was conducted according to ASTM C1609. Beneath the sample, two linear variable differential transformers [LVDTs, Tokyo Sokki, model FDP 50A with 300 \(\times\) 10\({}^{-6}\) strain/mm sensitivity (Tokyo, Japan)] were installed to measure the mid-span displacement of the samples during the test. Moreover, a 30 kN universal testing machine [INSTRON, Model 3367 (Norwood, Massachusetts, US)] was employed to conduct the flexural test at a loading rate of 0.2 mm/min. It worth noting that the two LVDTs were connected to a data acquisition system (Tokyo Sokki, model TDS-630 with a speed of 1000 channels in 0.1 s) to synchronize and acquire the test data. The compressive and flexural tests were conducted on UHPC samples with and without fibers (UHPC-C) for comparison purposes. In the current research, the mechanical properties of the steel bars were evaluated by performing the uniaxial tensile test using 600 mm (length) specimens as per ASTM A370 specifications. The test was conducted under displacement-controlled conditions at a rate of 0.0187 mm/s. From this test, the stress-strain behavior of the high-strength steel was obtained and utilized to evaluate the material's yield strength and Young's modulus. It is worth noting that the result for the earlier material tests represents the average of three samples. In the current investigation, the structural behavior of the control and reinforced UHPC beams (Figure 2 and Table 5) was investigated under four-point loading conditions. The test's schematic diagram is shown in Figure 4a. This test was performed by utilizing Toni Technik's servo-controlled hydraulic universal testing machine (Model 2073, 3000-kN capacity). The instrumentation during the test included three strain gauges (Figure 4b) attached to the specimen's top and front faces to measure the strain response of concrete. Two strain gauges were additionally attached to the embedded reinforcement of B2-B6 in order to acquire the tensile strain of steel bars. \begin{table}
\begin{tabular}{c c c c} \hline \hline
**No.** & **Code** & \(\varnothing\)**(mm)** & **Reinforcement Ratio \(\rho\)**(\%)** \\ \hline
1 & B1 & - & - \\
2 & B1-R & & - \\ \hline
3 & B2 & & \\
4 & B2-R & & \\ \hline
5 & B3 & & \\
6 & B3-R & 10 & 0.84 \\ \hline
7 & B4 & & \\
8 & B-R & 12 & 1.21 \\ \hline
9 & B5 & & \\
10 & B5-R & 16 & 2.14 \\ \hline
11 & B6 & & \\
12 & B6-R & 20 & 3.35 \\ \hline \hline \end{tabular}
\end{table} 
Table 5: Reinforcement details for beam specimens. Moreover, two linear variable differential transformers (LVDTs--Tokyo Sokki, model FDP 50A with 300 \(\times\) 10\({}^{-6}\) strain/mm sensitivity) (Figure 4b) were attached at the specimen's mid-span to obtain its real-time mean defection. Moreover, two horizontal/inclined LVDTs were fixed to measure the crack width after its initiation. In the current experimental testing, displacement-controlled loading conditions were applied at a rate of 0.4 mm/min to the beam's top surface (Figure 4a) until final failure. It is worth mentioning that all the earlier-described accessories (LVDTs, strain gauges, and load cell) were synchronized to a data acquisition system (Tokyo Sokki, model TDS-630 with a speed of 1000 channels in 0.1 s) to gain the test data.