## 3 Experimental Program  
### Specim Details  
To evaluate the structural performance of the proposed system and analyze its splicing performance, one monolithic RC test beam (hereafter, control reinforced concrete CRC) and two PC modular beam specimens were fabricated. The connection length of the PC modular which shown in Figure 2 has a significant impact on the structural performance of the entire system; therefore, it was set as a variable. The notation of specimens is presented in Figure 5. The material properties were measured by Korean standards. Korean standards specified that the material properties could be determined as the average test results of three or more specimens. The compressive strength test of concrete was carried out according to the Korean standard KS F 2405 [18]. Three concrete cylinders (150 \(\times\) 300 mm) were manufactured for compressive strength test. The compressive strength of concrete was measured after 28 days of curing and the average of three specimens was 23.12 MPa. The compressive strength of non-shrink mortar was measured through the Korean standard KS L 5105 [19]. Three cube specimens (50 \(\times\) 50 \(\times\) 50 mm) were tested, and the average compressive strength of non-shrink mortar was 58 MPa. The yield strengths of deformed reinforcement and steel plates were measured according to the Korean standard KS B 0802 [20], and three specimens were tested. The deformed reinforcement was 19 mm in diameter, and stirrups with a diameter of 10 mm were arranged at 150 mm intervals to prevent shear failure of the beams. The average yield strength of reinforcement was 406.49 MPa. The steel plate inserted into the PC modular was manufactured using SS275  
Figure 4: Construction process of proposed precast concrete modular beam system: (**a**) inserting an I-shaped steel plate into a U-shaped steel plate; (**b**) splice connection between steel plates; (**c**) bolt connection between steel plates; (**d**) injection of non-shrink mortar. Figure 3: Steel plates: (**a**) I-shaped steel plate; (**b**) U-shaped steel plate. Figure 2: Scheme of proposed precast concrete modular beam system. steel, and the average yield strength of 269.79 MPa. Figure 6 presents the stress-strain curve of a representative specimen. The dimensions of the test specimens are shown in Figure 7: 300 mm wide and 350 mm high, with a total length of 4500 mm. In Figure 7, only the left module is shown for the PCM test specimen; the right module is symmetrical. Details of the test specimens are shown in Table 1.  
Figure 5: Notation of specimens. Figure 6: _Cont._ \begin{table}
\begin{tabular}{c c c c c c c} \hline \multirow{3}{*}{**Specimen**} & \multirow{3}{*}{**Variable**} & \multirow{3}{*}{**Dimension** (b\(\times\)h\(\times\)l, mm)**} & \multicolumn{3}{c}{**Compressive**} & \multicolumn{1}{c}{**Compressive**} & \multicolumn{1}{c}{**Yield Strength**} \\  & & **(b\(\times\)h\(\times\)l, mm)** & **Strength of** & **Strength of** & **of Deformed** & **Yield Strength** \\  & & & **Concrete** & **Non-Shrink Mortar** & **Reinforcement** & **of Steel Plate** \\ \hline CRC & Control & & & - & & - \\ \hline PCM-A & \
\begin{tabular}{c} Connection \\ length \\ (350 mm) \\ \end{tabular} & \(300\times 350\times 4500\) & \(23.12\) & \(62.58\) & \(406.49\) & \(269.79\) \\ \hline PCM-B &
\begin{tabular}{c} Connection \\ length \\ (700 mm) \\ \end{tabular} & \(300\times 350\times 4500\) & \(23.12\) & \(62.58\) & \(406.49\) & \(269.79\) \\ \hline \end{tabular}
\end{table} 
Table 1: Details of specimens. Figure 6: Stress–strain curve: (**a**) concrete; (**b**) non-shrink mortar; (**c**) deformed reinforcement; (**d**) steel plate. Figure 8 shows the process of constructing the proposed PC modular beam. A factory-produced PC modular beam was transported to the site and the steel plate was assembled. Finally, shear studs were used to assemble the steel plates. The PC modules were spliced by injecting non-shrink mortar.