fig15
![Time-domain instability mechanism for artificial boundary condition of semi-infinite medium described by discrete rational approximation](https://image.oaes.cc/200a98ce-4b02-453e-8ae6-851f6f45ceac/dpr3038.fig.15.jpg)
Figure 15. Frequency domain analysis of horizontal motion coupled system of circular foundation. (A) SDOF coupled system frequency domain characteristic of base impedance; (B) SDOF coupled system frequency domain characteristic of structure; (C) SDOF coupled system gain margin analysis of coupled system; (D) Comparison of frequency domain characteristics between rational function and original data.