# Seismic Effect of Marine Corrosion and CFRP Reinforcement on Wind Turbine Tower
## 2 Establishment and Verification of FE Model
### Establishment of FE Model of Wind Turbine Tower  
The methods of simulating soil structure interaction (SSI) include the fictitious anchor point method, the m method, the P-y curve method and the actual soil modeling method. Considering the large amount of calculation of seismic time history analysis, the actual soil modeling method is not applicable to the analysis of this study. In addition, the m method and the P-y curve method need to add many nonlinear springs to the structure, which will submerge the influence of corrosion and CFRP reinforcement on the structure in the deformation of nonlinear springs. In practical engineering, the pile foundation of wind turbine towers is usually embedded in the foundation or rock stratum. Therefore, the assumed embedded point method is used to consider the soil structure interaction (SSI). As shown in Figure 2, calculate the embedded depth of long elastic pile according to the format (1)\(\sim\)(2) Code for pile foundation of harbor engineering [20]. \[t\ =\ \eta T \tag{1}\]  
\[T\ =\ \sqrt[5]{\frac{E_{p}I_{p}}{mb_{0}}} \tag{2}\]  
Here: \(\eta\) is the coefficient, taking 1.8-2.2, the smaller value is taken when the pile top is hinged or the free length of the pile is larger, and the larger value is taken when the pile top angle does not rotate or the free length of the pile is smaller; \(T\) is the relative stiffness of the pile; \(E_{p}\) is the elastic modulus of the pile material; \(I_{p}\) is the moment of inertia of the pile section; \(m\) is the proportional coefficient of the horizontal resistance coefficient of the foundation soil at the pile side increasing with the depth; \(b_{0}\) is the converted width of the pile. The FE model of the wind turbine tower without corrosion is established by ABAQUS. The 8-node solid element C3D8R is selected for the tower structure, the material is Q345B steel. The mechanical parameters of steel are shown in Table 1. In order to study the mechanical behavior of the structure under earthquakes, the strengthening constitutive model of steel under cyclic action has been adopted [21; 22]. Figure 1: Structural dimensions and geological conditions of wind turbine tower. [PERSON] et al. [23; 24] took the 5 \(\mathrm{w}\mathrm{m}\) wind turbine tower as the research object and studied the coupling effect of blade and tower tubes on the dynamic response of the wind turbine tower structure. It is found that the influence of the blade on the dynamic response of the wind turbine structure cannot be ignored. Therefore, in order to ensure the accuracy of calculations, the blade structure is established in ABAQUS, and the material is simplified according to the equal mass. The equivalent density is 171.58 kg/m\({}^{3}\). According to the principle of equal mass, the density of the engine room and the wheel hub are equivalent. The weight of the cabin is 131.43 tons, and the hub is 27.78 tons. The pile bottom is completely fixed. Tie constraints are used between the blade and the hub and in the engine room. Because the grid generation will affect the calculation speed and accuracy, on the premise of ensuring the calculation accuracy, the tower structure is encrypted, and other parts of the grid are simplified. When establishing the finite element model, refer to the research of [PERSON], [PERSON] et al. and [PERSON] et al. [25; 26]. The bolted connection is simplified as a steel ring inside the tower to reduce the number of elements in the finite element model. The overall finite element model of the structure is shown in Figure 3.