Influences of Window Function on the Subsoil Damping Ratio

Influences of window function selection on the subsoil damping ratio of a massive concrete foundation is presented in this paper based on logarithmic decrement method in the time domain and point-peak method in the frequency domain. Little damping ration difference among smoothing curves of adjacent three point averaging, Hanning window and Hamming window is found both in the time domain and frequency domain. Influences of smoothing times on the subsoil damping ration is also discussed. It shows that damping ratio decreases as the smoothing times increases in the time domain, and on the contrary in the frequency domain. Selection of window function and smoothing time should be studied furthermore based on the real damping ration value both theoretically and experimentally.