## 3 Test Results
### Design Methods of Load-Bearing Capacity
#### 3.3.3 Design Method for BFRP Grid-Reinforced Concrete Beams  
Taking a general rectangular cross-section beam as an example, it is assumed that the size of the beam is given, the length of the beam is \(l\), the width and height of the normal section of the beam are \(a\) and \(h\), the height of the bottom protective layer of the beam is \(b_{h}\), and the thickness of the side protective layer is \(b_{c}\). The size of the grid in composite material grid panels is a critical dimensional parameter. In order to ensure the maximum particle size of the coarse aggregates used in the concrete, the grid size of grid panels made of composite materials cannot be smaller. \[l_{w}=b_{h} \tag{17}\]  
The length of the longitudinal grid bars along the longitudinal length of the beam, whether it is a horizontal or vertical grid panel, should match the length of the beam overall. \[l_{z}=l \tag{18}\]  
The width of the horizontal grid panel should match the width of the beam less the thickness of the side protective layer, and the length of the longitudinal grid bars should equal the height of the beam, as \(a-2b_{c}\). To guarantee the stability of the grid framework and prevent damage during pouring, the optimal spacing for the rectangular grid-shaping material is between 200 mm and 350 mm. Using a typical concrete beam as an example, its dimensions are 200 mm \(\times\) 300 mm in cross-section, and it has a 2500 mm overall length. The concrete grade utilized for the beam is C30. The beam employs a composite material grid framework using basalt fiber composite grid panels. The grid framework consists of four parts, which are two side composite material grid panels, the bottom composite material grid panel, and the grid panels used for shaping and fixing. The composite material grid panels are made of the same materials as are utilized in this paper. The precise parameters are in Table 10:  
The 50 mm \(\times\) 50 mm grid size of the composite material grid panel is developed for ease of pouring and cutting, based on the beam dimensions and particle grading in actual engineering applications. Taking a side protection layer width of 25 mm, it can be calculated that there should be four longitudinal grid bars at the bottom. The arrangement of the grid framework involves binding the lowest longitudinal distributed grid bars on the side grid panel and the bottom grid panel at the same horizontal height. Therefore, when calculating the equivalent reinforcement ratio, the lowest longitudinal distributed grid bars at the same horizontal height need to be considered. In this example, there is a total of six grid bars. The width of the grid bars, according to the chosen range mentioned above, is set to be 10 mm wide. \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Types of Specimens** & \begin{tabular}{c} **Tensile Elastic** \\ **Modulus (Gpa)** \\ \end{tabular} & \
\begin{tabular}{c} **Tensile Strength** \\ **(Mpa)** \\ \end{tabular} &
\begin{tabular}{c} **Elongation at Break** \\ **(\%)** \\ \end{tabular} \\ \hline BFRP grid & 51 & 357 & 0.27 \\ \hline \hline \end{tabular}
\end{table} 
Table 10: Mechanical properties of BFRP grid. \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Specimen Number** & \begin{tabular}{c} **Test Value** \\ **(kN)** \\ \end{tabular} & \
\begin{tabular}{c} **ACI** \\ **(kN)** \\ \end{tabular} &
\begin{tabular}{c} **Test Value/** \\ **Calculated Value** \\ \end{tabular} \\ \hline BGCS-3-a & 230.13 & 181.58 & 0.79 \\ BGCS-3-b & 193.25 & 181.58 & 0.94 \\ BGCS-5-a & 296.72 & 283.64 & 0.96 \\ BGCS-5-b & 277.55 & 283.64 & 1.02 \\ HBGCS-3 & 220.25 & 214.11 & 0.97 \\ HBGCS-5 & 291.79 & 316.19 & 1.08 \\ \hline \hline \end{tabular}
\end{table} 
Table 9: Comparison of test values and calculated values of shear cracking load. Based on the above conditions, the optimal thickness for the composite material grid panel is calculated to be 10 mm. The dimensions of the grid framework have been calculated after determining the grid panel thickness and providing the grid size and bar width.