Presented by Merrick Taylor
This Presentation will provide a brief review of performance-based design (PBD) as it applies to geotechnical engineering practice. Building on the limit state framework in building codes and standards the approach is now commonly adopted to develop design solutions that meet both the code requirements for life safety, with the flexibility to incorporate a client’s specific objectives for seismic performance and resilience. For geotechnical practitioners, the PBD approach is essentially pragmatic and allows for tolerable ground movements under rare events, while maintaining continuity of service for buildings and infrastructure under frequent events. Uncertainties are significant and compounding, owing to the nature of seismic hazard, and our limited ability to accurately predict ground and structural response and ultimately damage. Consequently, for PBD to be successful those uncertainties need to be adequately considered to develop robust solutions that are relatively insensitive to our acknowledged limitations. Challenges remain in high seismicity locations such as Wellington where seismic loads are very high, compounded where weak ground conditions are present (e.g., steep fractured and weathered rock slopes, saturated alluvial soils). With an impending code update likely to raise seismic design loads above those in NZS1170.5, it is expected that engineers will be required to consider more closely the project-specific performance requirements to achieve practical and affordable design solutions.