SEISMIC RESPONSE ANALYSIS ON EARTHQUAKE MOTION AT ZAFARANA WIND TURBINE FARM, EGYPT

Document Type : Original Article

Authors

Civil Engineering Department, Faculty of Engineering, Fayoum University, Egypt.

Abstract

Zafarana wind turbine towers farm, which is located 120 km south of Suez on the Red Sea, lies in not only the highest wind speed zones but also the most seismically active areas. Al-Aqaba 1995 earthquake acceleration time history, which recorded at the Eilat station, used at the bedrock level of this research. The peak ground acceleration (PGA) of the horizontal component was almost about 0.10g at the ground surface. The effect of local geologic and soil conditions on the intensity of the ground shaking discussed in this paper. Severe damage occurred due to the amplification of the earthquake motion because the site response analysis considered in the seismic response analysis. Subsurface geotechnical and geophysical (down-hole) data in eight different sites in Zafarana wind turbine farm that carried out used to assess the site response analysis on earthquake ground motion in the studied area. According to the shear wave velocities obtained from the field tests, the classification of soil at Zafarana wind turbines farm was Soil Class B and Soil Class C according to the International Building Code (IBC). Thus, the ground response analyses conducted considering the nonlinear behavior of the soil deposits using both equivalents linear and nonlinear methods. The 1-D nonlinear approach, included in DEEPSOIL v7.0, used to determine the nonlinear soil properties on seismic wave propagation through the soil column and compared to those from the equivalent linear approach, which analyzed using SHAKE 2000. The results comparison showed the same shape of spectral acceleration versus period curves for both equivalent and nonlinear analyses, and the peaks of spectral accelerations in the period range of (0.1_0.50) s. The results showed that the nonlinear amplification factors were more than the equivalent method especially in zones that classified as Soil Class C; however, the amplification of the ground motion was approximately the same for both approaches in zones that classified as Soil Class B. Finally, this paper concludes that the nonlinear analysis should be considered as the soil is softer and the equivalent linear analysis can be used at the zones that classified as Soil Class B or stiffer.

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