# Study on Bending Performance of Tightly Spliced Truss-Reinforced Plate-Honeycomb Flat Beam
## 4 Theoretical Analysis and Design Method
### Verification of Ultimate Bending Capacity Calculation  
In order to verify the applicability of the formula and simplified calculation formula for calculating the ultimate bending bearing capacity of specimens using the double T-shaped steel method, the bending bearing capacity of honeycomb composite flat beams under different section heights and hole-height ratios was explored by comparing the finite element model calculation results in the previous text. Table 5 presents the results and comparative analysis data of three different calculation methods, including the double T-shaped steel calculation method (DT method), web reduction calculation method (RWP method), and finite element method (FE method). The ultimate bending bearing capacity of the specimen calculated by the equivalent stress method is less than the finite element simulation value, indicating that the calculation of the bending bearing capacity of the specimen according to the formula given in this chapter is conservative and has sufficient safety. The main reasons why the calculated value of the formula is less than that of the finite element method are: (1) The formula ignores the tensile strength of concrete and the reinforcement in the concrete flange plate for the improvement of the bending bearing capacity of the specimen; (2) When calculating the formula, the effect of the H-shaped steel shear connection key and stiffener in the composite specimen was not considered. The H-shaped steel shear connection key and stiffener appear  
\begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline
**Specimen** & **Height of Section** & **Hole–Height** & **DT** & **RWP** & **FE** & **Error of DT** & **Error of** \\  & **(mm)** & **Ratio** & **(kN)** & **(kN)** & **(kN)** & **Error of DT** & **RWP** \\ \hline ZB1 & 200 & 0.45 & 77.79 & 87.01 & 95.85 & 18.84\% & 9.22\% \\ ZB2 & 200 & 0.50 &  
relative compression with the concrete during bending, which suppresses the deformation of the specimen and improves the flexural bearing capacity of the specimen. The error of formula A is basically between 17% and 20%, while the error of the RWP method is basically between 7% and 12%, indicating that the accuracy of the simplified calculation formula is higher than that of the double T-shaped steel method calculation formula. When calculating using the double T-shaped steel method, the connection effect of the web plate at the honeycomb steel beam web plate pier on the upper and lower T-shaped steel sections was not considered. The contribution of the upper and lower separated T-shaped steel to the bearing capacity of the composite flat beam was calculated separately, and the formula calculation value was generally lower than the finite element simulation result. From Table 5, it can be seen that the error of the DT method increases with the increase in the honeycomb hole-height ratio. When the hole-height ratio is 0, the formula calculation error is only 11.50%, which is significantly reduced compared to other hole-height ratio errors. The calculation results of the DT method for solid web composite flat beams are significantly better than those of honeycomb composite flat beams, and this formula takes into account the weakening effect of honeycomb holes too conservatively. The RWP method shows a relatively stable error in the formula calculation value when the cross-sectional height of the composite flat beam remains constant, but the error tends to decrease with the increase in the cross-sectional height of the honeycomb composite flat beam. It shows that the calculation of the bending bearing capacity of specimens with the same section height and different hole-height ratios has relatively stable results, but there is still about a 10% safety margin relative to the finite element method.