Kajian site spesific seismic analysis (SSSA) tanah lunak lapis tebal di kawasan tol Semarang-Demak

Abstract

In this case, there is a deep (80 m) soft soil layer located at the Semarang- Demak toll road site. Soft soil has the potential to amplify low-frequency

seismic waves that can trigger resonance and high-amplitude seismic load excitation. This would threaten the secure of the infrastructure above it.

Therefore, in the seismic design of the infrastructure on the site, site- specific analysis needs to be conducted. This study discusses the SSSA

analysis of the Semarang-Demak toll road site using 1D dynamic analysis methods, both linearly and nonlinearly, with DEEPSOIL software. The soil dynamic analysis is conducted with some input data, i.e., earthquake data, soil dynamic parameters, and soil stratigraphy profiles that are matched with the response spectra design (SNI 2833:2016 code) of the site. The results show that both equivalent linear and nonlinear site response analyses generate significantly higher responses than response spectra designed below the soil natural period. However, in the higher natural period, both soil analysis results show higher response amplification at a particular frequency; nonlinear analysis exhibits lower responses than linear equivalent analysis. Thus, the nonlinear analysis more accurately represented the real condition of the site in calculating seismic response analysis than the than the equivalent linear method, resulting in more coincidence with the response spectra design.