# Flexural Capacity of a New Composite Beam with Concrete-Infilled Tubular Lower Flange
## 2 Experimental Program  
### Test Specimens  
In this study, a total of seven specimens were manufactured and tested for the evaluation of the flexural strength of the proposed composite beam. Five of them are non-composite beam specimens at construction stage, and the other two are fully composite specimens with floor deck components.  
Figure 1: Composite beam system with tubular lower flange.  
Figure 2: Composite beam section.  
The test parameters of the non-composite beam specimens include the depth of the beam, existence of web openings, and location of main rebars. The conventional wide flange specimen is also added as the reference non-composite specimen for comparison purposes. The two fully composite specimens include the proposed composite beam specimen with deep floor deck and a conventional wide flange specimen with a truss floor deck. In all of the proposed composite beam specimens, its lower tubular flange is reinforced with four D32 rebars. The notation used to indicate each set of test parameters is presented in Figure 3. The details of the seven specimens are summarized in Table 1, and their cross-sectional shapes of the seven specimens are illustrated in Figure 4. All the specimens with web openings have exactly the same opening details as shown in Figure 5.  
The compressive strength of concrete (\(F_{ck}\)) was measured in accordance with the standards of [13], and the measured average values are summarized in Table 2. Its modulus of elasticity (\(E_{c}\)) is estimated using the following formula provided in [14]:  
\[E_{c}=8500\sqrt[3]{F_{cu}}, \tag{1}\]  
where \(F_{cu}\) is the cube compressive strength of concrete and can be calculated using \(F_{cu}=F_{ck}+\Delta F\). If \(F_{ck}\) is less than 40 MPa, \(\Delta F\) is given as 4 MPa. The material properties of steel components of the test specimens are listed in Table 3, which were measured per ASTM A370 [15].  
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multirow{2}{*}{**Specimen**} & **Type of** & **Steel Beam** & **Existence of** & **Location of** & **Type of** \\  & **Specimen** & **Depth (mm)** & **Web Openings** & **Main Rebars** & **Floor Deck** \\ \hline
588-WF-X & & 588 & & \(\mathrm{N/A}\) & \\ \cline{2-5}
505-TF-X-R1 & & & No & & \\ \cline{2-5}
505-TF-O-R1 & Non-composite & 505 & & Bottom & \(\mathrm{N/A}\) \\ \cline{2-5}
505-TF-O-R2 & & & Yes & Middle & \\ \cline{2-5}
390-TF-O-R1 & & 390 & & Bottom & \\ \cline{2-5}
738-WFC-X-X-TD & Fully composite & 588 & No & \(\mathrm{N/A}\) & Truss deck \\ \cline{2-5}
585-TFC-O-R1-DD & & 505 & Yes & Bottom & Deep deck \\ \hline \hline \end{tabular}
\end{table}
Table 1: Details of test specimens.  
Figure 3: Specim identification.  
Figure 4: Cross-sectional shapes of test specimens.  
Figure 5: Web opening details of test specimens.  
\begin{table}
\begin{tabular}{c c c} \hline \hline
**Concrete Type** & **Compressive Strength** & **Modulus of Elasticity** \\ \hline Tube infilled concrete & 29.8 & 27,474.5 \\ Slab deck concrete & 29.4 & 27,360.1 \\ \hline \hline \end{tabular}
\end{table}
Table 2: Concrete material properties (unit: N/mm\({}^{2}\)).  
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**Component** & **Yield Strength** & **Ultimate Strength** & **Yield Strain** \\ \hline Upper flange & 328.3 & 513.3 & 1561.4 \\ Web & 399.9 & 541.6 & 1844.9 \\ Lower tubular flange & 456.5 & 537.6 & 1991.8 \\ Main rebars & 548.6 & 698.2 & 2676.2 \\ \hline \hline \end{tabular}
\end{table}
Table 3: Material properties of steel components (units: N/mm\({}^{2}\), \(\mu\)m/m).