# Study on Wind Resistance Performance of Transmission Tower Using Fixture-Type Reinforcement Device
## 2 Fixture-Type Reinforcement Device (FRD)
### Finite Element Simulation of the FRD  
To analyze the enhancement effect of the FRD on the mechanical properties of the main component, a typical angled steel component was selected as the prototype, and the finite element models are built based on the Abaqus platform. The length of the angled steel component is 1.5 m; the thickness and the width of the L-shaped section are, respectively, 5 mm and 75 mm. The finite element models of the main component and the reinforced one are established as shown in Figure 2.  
The eight-node solid elements are used to simulate all the parts of the model. The material of the two models is Q235, and its mechanical properties are listed in Table 1. The reinforcing component shares the same sectional dimensions as the main component, but its length is only 1 m. The height of the L-type steel plate and the crossed steel plate is 100 mm, while their thickness is 5 mm, which is identical to that of the main component. The effect of the bolts connecting different parts of the model are simulated by the pressure directly exerted on the surfaces of them, including the L-type steel plate, the crossed steel plate, and the reinforcing component. Two steel plates are set on both ends of the main component so as to act as the loading plates. The vertical load is applied directly in the form of displacement to the top plate of the two models, and the bottom plates of them are constrained. In this way, the load-displacement relationship can be derived to assess the enhancement effect of the FRD. It can be seen in Figure 2 that three fixture pairs are used as the illustration example. Actually, the number of the fixture pairs is a key factor that could influence the enhancement effect of the FRD, and therefore different numbers, namely 2 to 4, of the fixture pairs are investigated in this section. Figure 1: The configuration of the FRD: (**a**) sectional view; (**b**) 3D view; (**c**) exploded view. The failure mode of the original model is given in Figure 3a. As can be seen from the figure, when not reinforced, the main angled steel component will undergo plastic deformation and buckling failure at the middle part due to axial displacement loading. When it is reinforced by the FRD with different numbers of fixture pairs, the failure modes are represented in Figure 3b. It can be seen that the failure mode of the reinforced model with two fixture pairs is nearly identical to that of the original model, which indicates the number of the fixture pairs is not sufficient to avoid the buckling failure of the entire component. However, when three or four fixture pairs are used in the reinforcement, the failure mode of the model switches to the local buckling near the top and/or the bottom fixture pair. That is to say, using three or more fixtures can change the loading and deformation patterns of the reinforced models so as to prevent the buckling failure of the entire component. \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Type** & \begin{tabular}{c} **Density** \\ **(kg/m\({}^{3}\))** \\ \end{tabular} & \
\begin{tabular}{c} **Elastic Modulus** \\ **(MPa)** \\ \end{tabular} &
\begin{tabular}{c} **Poisson Ratio** \\ **(MPa)** \\ \end{tabular} \\ \hline Q235 & 7850 & 2.06 \(\times\) 105 & 0.31 & 235 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Mechanical properties of the material. Figure 3: Failure modes of the models: **(a)** the original model; **(b)** the reinforced models. Figure 2: Finite element models: **(a)** original model; **(b)** reinforced model. The load-displacement curves derived from these models are plotted in Figure 4. It can be seen that these four curves share a similar varying trend such that they get their peak values of load at the displacement of around 2 mm. The initial stiffness values of these models are very close because only the main component participates in taking the vertical load at the beginning.