Recent Application of Site-Specific Geotechnical Earthquake Engineering in Christchurch CBD
Fauzi et al.
This paper presents the utilisation of site-specific geotechnical earthquake engineering for the proposed structural retrofit design of a building in the Christchurch CBD. This study includes Probabilistic Seismic Hazard Analysis (PSHA), development of time histories, Site Specific Response Analysis (SSRA), and Dynamic Soil-Structure Interaction (DSSI). PSHA and deaggregation were computed using Miyamoto's New Zealand seismic hazard model using open-source Seismic Hazard Analysis (SHA) software (OpenQuake 2.1.0). The model includes active faults, area sources, and time-dependent point source model based on the modified-Oomori Law. The model was compared with the New Zealand National Seismic Hazard Model (NZSHM) which form the basis for NZS 1170.5:2004. A suite of eleven spectrally-matched, single-component horizontal earthquake acceleration time histories, was developed for each of the 25-year and 500-year return period loading conditions. Then, the time histories were propagated from Riccarton Gravel to ground surface using non-linear, one dimensional (1D) total stress analysis in DEEPSOIL 6.1. A building with 3.0m deep basement at the ground surface was analysed in ETABS software using an elastoplastic model. Dynamic soil properties were derived from the analysis of geotechnical data acquired from the site, this included shear wave velocity (Vs) profiles from downhole tests. This approach requires more effort but does provide a better understanding of soil-structure interaction and anticipated building performance for future seismic events.