**4. Parametric Analysis**

#### *4.1. Tower Displacement*

The tower displacement under different wind speeds is studied. The wind speed at sea level is 4 m/s, 8 m/s, and 12 m/s, respectively. The percentage of the thrust wind load is 96.31%, and the percentage of the distributed wind load is 3.69%. As shown in Figure 10, the tower displacement is largely influenced by the wind speed. When the wind speed is 4 m/s, the increasing rate of tower displacement is relatively small. When the wind speed

is 8 m/s, the increasing rate rises to a certain degree. When the wind speed is 12 m/s, the increasing rate is significantly larger than the increasing rate when the wind speed is 4 m/s.

**Figure 10.** The influence of the wind speed on the tower displacement.

The influence of the foundation impedance on the tower displacement is also studied. Define *α<sup>K</sup>* = *K*∗ /*K*∗, where *K*∗ is the modified foundation impedance matrix and *α<sup>K</sup>* is valued from 0.1~2 to analyze the influence of the foundation impedance on the maximum tower displacement. As shown in Figure 11, when the foundation impedance is relatively small, the tower displacement is large. With increasing foundation impedance, the tower displacement decreases rapidly. Additionally, with increasing foundation impedance, the tower displacement decreasing speed slows. When the foundation impedance reaches 2.0 its original impedance, the tower displacement remains almost unchanged.

**Figure 11.** The influence of the foundation impedance on the tower displacement.
