# Seismic Effect of Marine Corrosion and CFRP Reinforcement on Wind Turbine Tower
## 4 Shaking Table Test
### Affect of Corrosion on Dynamic Response of Structure  
The acceleration time history curve of the top of the structure under the El Centro earthquake is shown in Figure 26. It can be seen that with the reduction of the wall thickness of the steel tower, the acceleration response of the top of the structure shows a downward trend, and the acceleration response of the corroded structure is smaller than that of the noncorroded structure in the whole seismic loading process. It shows this characteristic under different peak accelerations and different types of seismic waves. It can be seen from Figure 27 that the corrosion causes the displacement of the top of the structure to increase, and the negative displacement of the structure is greater than the positive displacement of the structure. According to the analysis of the acceleration change at the top of the structure, the corrosion of the tower structure will lead to the local reduction of the structural stiffness, which will reduce the acceleration response and increase the displacement response of the structure under the earthquake action. \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Loading Condition** & **Experimental Condition** & **Wall Thickness/mm** & **Earthquake Records** & **PGA/Gal** \\ \hline No. 1 & El-01 & 3 & El Centro & 35 \\ No. 2 & El-02 & 3 & El Centro & 70 \\ No. 3 & Ni-01 & 3 & Nihonkai-Chubu & 35 \\ No. 4 & Ni-02 & 3 & Nihonkai-Chubu & 70 \\ No. 5 & Hy-01 & 3 & Hyogoken-Nanbu & 35 \\ No. 6 & Hy-02 & 3 & Hyogoken-Nanbu & 70 \\ No. 7 & El-03 & 2.8 & El Centro & 35 \\ No. 8 & El-04 & 2.8 & El Centro & 70 \\ No. 9 & Ni-03 & 2.8 & Nihonkai-Chubu & 35 \\ No. 10 & Ni-04 & 2.8 & Nihonkai-Chubu & 70 \\ No. 11 & Hy-03 & 2.8 & Hyogoken-Nambu & 35 \\ No. 12 & Hy-04 & 2.8 & Hyogoken-Nanbu & 70 \\ No. 13 & El-05 & 2.65 & El Centro & 35 \\ No. 14 & El-06 & 2.65 & El Centro & 70 \\ No. 15 & Ni-05 & 2.65 & Nihonkai-Chubu & 35 \\ No. 16 & Ni-06 & 2.65 & Nihonkai-Chubu & 70 \\ No. 17 & Hy-05 & 2.65 & Hyogoken-Nanbu & 35 \\ No. 18 & Hy-06 & 2.65 & Hyogoken-Nambu & 70 \\ No. 19 & El-07 & 2.5 & El Centro & 35 \\ No. 20 & El-08 & 2.5 & El Centro & 70 \\ No. 21 & Ni-07 & 2.5 & Nihonkai-Chubu & 35 \\ No. 22 & Ni-08 & 2.5 & Nihonkai-Chubu & 70 \\ No. 23 & Hy-07 & 2.5 & Hyogoken-Nanbu & 35 \\ No. 24 & Hy-08 & 2.5 & Hyogoken-Nambu & 70 \\ No. 25 & CF-El-09 & 2.8 & El Centro & 35 \\ No. 26 & CF-El-10 & 2.8 & El Centro & 70 \\ No. 27 & CF-Ni-09 & 2.8 & Nihonkai-Chubu & 35 \\ No. 28 & CF-Ni-10 & 2.8 & Nihonkai-Chubu & 70 \\ No. 29 & CF-Hy-09 & 2.8 & Hyogoken-Nanbu & 35 \\ No. 30 & CF-Hy-10 & 2.8 & Hyogoken-Nanbu & 70 \\ No. 31 & CF-El-11 & 2.65 & El Centro & 35 \\ No. 32 & CF-El-12 & 2.65 & El Centro & 70 \\ No. 33 & CF-Ni-11 & 2.65 & Nihonkai-Chubu & 35 \\ No. 34 & CF-Ni-12 & 2.65 & Nihonkai-Chubu & 70 \\ No. 35 & CF-Hy-11 & 2.65 & Hyogoken-Nanbu & 35 \\ No. 36 & CF-Hy-12 & 2.65 & Hyogoken-Nanbu & 70 \\ No. 37 & CF-El-13 & 2.5 & El Centro & 35 \\ No. 38 & CF-El-14 & 2.5 & El Centro & 70 \\ No. 39 & CF-Ni-13 & 2.5 & Nihonkai-Chubu & 35 \\ No. 40 & CF-Ni-14 & 2.5 & Nihonkai-Chubu & 70 \\ No. 41 & CF-Hy-13 & 2.5 & Hyogoken-Nanbu & 35 \\ No. 42 & CF-Hy-14 & 2.5 & Hyogoken-Nanbu & 70 \\ \hline \hline \end{tabular}
\end{table} 
Table 8: Loading condition of shaking table test. Figure 27: Displacement comparison under El Centro earthquake; (**a**) El Centro 35 Gal; (**b**) El Centro 70 Gal; (**c**) Comparison of displacement peak. Figure 26: Comparison of structural accelerations under El Centro earthquake: (**a**) El Centro 35 Gal; (**b**) El Centro 70 Gal; (**c**) Comparison of acceleration peak. Figures 28 and 29 show the changes in peak acceleration and displacement at the top of the structure under the action of the Nihonkai-Chubu earthquake and the Hyogoken-Nanbu earthquake. The influence of corrosion on the seismic dynamic response of the wind power tower in the three kinds of earthquakes all shows the law that corrosion reduces the acceleration response of the tower and increases the displacement response of the tower.