Analysis of Seismic Characteristics and Dynamic Behavior of Bili-Bili Dam using HVSR Method and Dynamic Model

The Bili-Bili Dam in Gowa Regency, South Sulawesi, is a critical infrastructure with a high seismic risk due to its location in a seismically active region. This study utilizes the HVSR [Horizontal-to-Vertical Spectral Ratio] method and dynamic analysis to evaluate the seismic characteristics and the dynamic response of the dam structure to earthquakes. The results reveal significant variations in the dominant soil frequencies, with the highest value at BLI 04 [2.62 Hz] and the lowest at BLI 09 [1.29 Hz], and the highest amplification at BLI 04 [A0 = 5.66] and the lowest at BLI 23 [A0 = 1.41]. Additionally, the dynamic analysis indicates that the first vibration mode is dominated by X-direction deformation with a mass participation of 97.24% and a natural frequency of 0.52 Hz. The correlation between the HVSR dominant frequencies and the mode shape frequencies reveals the potential for resonance in certain areas, such as at BLI 04, which requires specific mitigation measures. These findings provide valuable insights for enhancing the seismic resilience of the Bili-Bili Dam through a more integrated soil-structure interaction-based design.