# Seismic Effect of Marine Corrosion and CFRP Reinforcement on Wind Turbine Tower
## 1 Introduction  
With the global warming caused by the greenhouse effect becoming more and more serious, the development of renewable energy is becoming more and more important. In renewable energy technology, in order to meet the growing demand for electricity, the use of wind turbines is growing exponentially. However, with the increase in generator design and power generation capacity, various engineering problems are gradually exposed [1, 2, 3]. With the rapid development of wind power generation, the number of wind power towers is increasing year by year, but the development of the research on the seismic performance of wind power towers is relatively lacking, especially for wind turbine towers suffering from marine corrosion, the research on the seismic performance after corrosion needs to be carried out urgently [4, 5, 6]. After the 2003 edition of \"guidelines for structural designof wind power equipment supports\" in Japan, considering the large-scale development trend of wind turbine towers, the code was revised in 2010 [7]. The main revised content includes: for wind turbine towers with a height of over 60 m, the structural calculation of the tower structure, anchorage position and foundation should be able to resist extremely rare earthquakes. The performance design method based on the limit state design method is adopted in the design. Therefore, it is necessary to study the influence of different corrosion degrees and earthquake types on the seismic performance and collapse of offshore wind turbine towers under rare earthquakes. [PERSON] et al. [8] comprehensively expounded the correlation of wind turbine seismic disasters, studied the key factors of wind turbine seismic design, and pointed out that more experimental studies should be carried out to clarify the seismic performance of wind turbine towers. [PERSON] et al. [9] studied the influence of near-field pulse type earthquakes and welding defects on wind turbine towers with 1.5 MW onshore wind turbine towers. The results show that welding defects can significantly reduce the seismic intensity required for the nonlinear response of wind turbine towers, especially under pulse type near-field earthquake excitation, the structural nonlinearity with welding defects develops faster and higher. [PERSON] et al. [10] studied the buckling and overturning characteristics of wind turbine towers under the action of pulsed near-fault earthquakes and far-fault earthquakes. It is found that the wind turbine tower is the most prone to overturning under earthquakes, and the yield of tower is the second possible failure mechanism, followed by the development of permanent deformation and overall buckling of tower. [PERSON] et al. [11] emphasized the importance of incorporating the pulsed near-field effect into the seismic design of wind turbines, especially for wind turbines located near active faults. [PERSON] [12] proposed a simplified calculation model for the dynamic interaction of water, sea ice and wind turbine towers under seismic action, which avoids the solution of complex nonlinear equations and reduces the calculation burden. According to the research on the corrosion characteristics of steel structures in seawater, due to the alternation of dry and wet, the splash zone has the fastest corrosion rate and the most serious corrosion degree [13; 14; 15; 16; 17]. [PERSON] et al. [18] used FEM (Finite Element Method) to study the seismic performance and buckling characteristics of corroed steel pipe piles. The analysis results show that the damage location of steel pipe piles has little effect on the bearing capacity. [PERSON] et al. [19] studied the corrosion rate of steel structures in Western wind farms, and the highest corrosion rate of steel was 0.83 mm/year. As mentioned above, there is little research on the corrosion of offshore wind turbines tower at present. Most of the existing research focuses on different earthquake types, but the influence of corrosion defects on the seismic performance of the structure is not considered at the same time.